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Printing Instructions
|
For problems with accessibility in using
figures and illustrations in this method,
please contact the author at (801) 233-4900.
These procedures were designed and tested for internal use by OSHA personnel.
Mention of any company name or commercial product does not constitute
endorsement by OSHA.
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2-BUTANONE (MEK) HEXONE (MIBK)
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Method number: |
1004 |
|
MEK: |
|
Target concentration:
OSHA PEL:
ACGIH TLV: |
200 ppm (590 mg/m3) TWA
200 ppm (590 mg/m3) TWA
200 ppm TWA 300 ppm STEL/C |
|
MIBK: |
|
Target concentration:
OSHA PEL:
ACGIH TLV: |
100 ppm (410 mg/m3) TWA
100 ppm (410 mg/m3) TWA
50 ppm TWA 75 ppm STEL/C |
|
Procedure: |
Active samples are collected by drawing workplace air through SKC Anasorb CMS (carbon molecular sieves)
sampling tubes with personal sampling pumps. Diffusive samples are collected by exposing either SKC
575-002 Passive Samplers or 3M 3520 OVMs to workplace air. Samples are extracted with carbon
disulfide containing 1% N,N-dimethylformamide and analyzed by GC using a flame ionization
detector. |
|
Recommended sampling time and sampling rate:
|
|
SKC CMS sampling tube:
SKC 575-002 Passive Sampler:
3M 3520 OVM: |
240 min at 50 mL/min (12 L)
240 min
240 min |
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Reliable quantitation limit (RQL) and standard error of estimate (SEE): |
|
|
MEK
|
|
MIBK
|
|
RQL |
SEE |
|
RQL |
SEE |
|
(ppb) |
(µg/m3) |
(%) |
|
(ppb) |
(µg/m3) |
(%) |
|
SKC CMS sampling tubes
SKC 575-002 Passive Sampler
3M 3520 OVM |
23 109 33 |
68 320 98 |
6.0 9.1* 8.3* |
|
9 94 35 |
36 384 144 |
5.9 9.1* 8.0* |
|
|
|
|
*For samples where sampling site atmospheric pressure and temperature are known. When either or both of
these values are unknown, see Section 4.4 for applicable standard errors of estimate. |
|
Special requirements: |
Report sampling site pressure and temperature when using diffusive samplers. Refrigerate samples for MEK and
MIBK upon receipt at laboratory. |
|
Status of method: |
Evaluated method. This method has been subjected to the established evaluation procedures of the Methods
Development Team. |
|
September 2000 |
Warren Hendricks |
Methods Development Team
Industrial Hygiene Chemistry Division
OSHA Salt Lake Technical Center
Sandy, UT 84070-6406 |
1. General Discussion
1.1 Background
1.1.1 History
Workplace determination of 2-butanone (methyl ethyl ketone, MEK) and of hexone (methyl isobutyl ketone, MIBK) is
of considerable interest to OSHA. Both MEK and MIBK rank in the top 15 most requested organic solvent analytes for
samples received at SLTC. This work was performed to provide OSHA with convenient active and diffusive sampling
methods to monitor workplace air for these chemical hazards. The two chemicals were evaluated simultaneously to
conserve SLTC resources. Evaluation of MEK revealed certain sampling and analytical problems, such as storage
instability and sample extraction difficulties, that are addressed in this method. Evaluation of MIBK was
straightforward and uneventful.
Current active sampling methods for MEK specify use of one of the following three sampling media and techniques:
1) two silica gel sampling tubes connected in-series (both tubes 150/75 mg sections, 3-L
air sample); 2) Carboseive S-III sampling tubes (130/65 mg sections, 3-L air sample);
or 3) Anasorb 747 sampling tubes (140/70 mg sections, 12-L air sample).1 The present sampling method for MIBK requires the use of charcoal tubes
(100/50 mg sections, 25-L air sample).2
The active sampling medium evaluated in this work (SKC Anasorb CMS) permits collection of a four-hour
(12-L) sample for both MEK and MIBK on the same sampling tube. Anasorb CMS is a proprietary carbon
molecular sieve that may be similar to Carbosieve S-III carbon molecular sieve marketed by Supelco.
Diffusive sampling methods allow a 4-hour sample to be collected on either SKC 575-002
Passive Samplers or on 3M 3520 Organic Vapor Monitors (OVMs). Storage stability tests showed that MEK is more stable
on 3M 3520 OVMs than on SKC 575-002 Passive Samplers. The method requires refrigerated storage of
samples upon laboratory receipt. Refrigerated storage is precautionary for SKC CMS sampling tubes and for 3M 3520
OVMs, but is obligatory for SKC 575-002 Passive Samplers. Refrigerated sample shipment for SKC
575-002 Passive Samplers is unnecessary, unless sample shipment is anticipated to be delayed for
more than three days.
Anasorb 747 sampling tubes were tested, but were found to be unsatisfactory for use in this method. Small Anasorb
747 (140/70 mg sections) sampling tubes did not have sufficient capacity to permit a four-hour MEK sample in the
presence of MIBK. Large Anasorb 747 (400/200 mg sections) sampling tubes have sufficient capacity, but ambient MEK
storage stability was poor. Anasorb 747 is the sorbent contained in SKC 575-002 Passive Samplers, and
MEK storage stability data for active and for diffusive samplers employing this sorbent were comparable. Tests
showed that Anasorb 747 does have adequate sampling capacity for MIBK in the presence of MEK, and that ambient
storage stability was satisfactory. Some of the Anasorb 747 sampling tube evaluation data is included in this
report for the preceding reasons, but it is for information only, and the use Anasorb 747 sampling tubes is not
recommended for this application.
1.1.2 Toxic effects 3 (This section is for information only and should not be taken
as the basis of OSHA policy.)
MEK
ACGIH's Documentation of the TLVs reports mild eye, nose, and throat irritation from exposure to MEK at 100 to
200 ppm. Low-grade intoxication has occurred at 300 to 600 ppm. The 100% response odor threshold was
10 ppm. Central nervous system effects were noted following exposures to mixtures of organic chemicals including
MEK. There was no excess cancer risk reported.
MIBK
ACGIH reports that MIBK is an irritant to the eyes, nose, throat, and skin. An odor threshold of 0.3 to 0.7 ppm
has been reported. Headache and nausea are common complaints of MIBK exposure. Exposure to high concentrations
could result in death because of its narcotic effects. Liver and kidney effects have been reported.
ACGIH, in the 1996 supplement to the Documentation of the TLVs
4, stated that dermal
and gastrointestinal absorption of MIBK could be significant. The BEI Committee recommended monitoring of MIBK in
urine at the end of the work shift as an indicator of recent exposure to MIBK. The recommended BEI value is 2 mg/L
MIBK in urine. Adjustment for creatinine is inappropriate.
1.1.3 Workplace exposure 5
MEK
MEK is used as a solvent in the surface coating industry and in dewaxing of lubricating oils. It is used in the
manufacture of colorless synthetic resins, artificial leather, rubbers, varnishes and glues. It is commonly used
with other solvents such as acetone, ethyl acetate, hexane, toluene, and alcohols.
MIBK
MIBK is used as a solvent in synthetic resinous paints, lacquers, aircraft dopes, and varnishes. It is also a
solvent for adhesives and rubber cement. It is used as a denaturant for ethyl alcohol, and to extract
pharmaceuticals and uranium fission products.
1.1.4 Physical properties and descriptive information
6,7
MEK
CAS number: |
78-93-3 |
vapor pressure: |
10.3 kPa at 20°C |
IMIS number: |
0430 |
flash point: |
-4°C (closed cup) |
molecular weight: |
72.10 |
odor: |
acetone-like |
boiling point: |
79.6°C |
lower explosive limit: |
1.8% (by volume) |
melting point: |
-86°C |
synonyms: |
butan-2-one; MEK |
appearance: |
colorless liquid |
solubility: |
water, all common industrial organic solvents |
specific gravity: |
0.805 at 20°C |
molecular formula: |
C4H8O |
MIBK
CAS number: |
108-10-1 |
vapor pressure: |
2.0 kPa at 25°C |
IMIS number: |
1385 |
flash point: |
18°C (closed cup) |
molecular weight: |
100.16 |
odor: |
pleasant, sweet |
boiling point: |
115.8°C |
lower explosive limit: |
1.4% (by volume) |
freezing point: |
-84.7°C |
synonyms: |
4-methyl-2-pentanone; MIBK |
appearance: |
colorless liquid |
specific gravity: |
0.8017 at 20°C |
solubility: |
1.91 g/mL in water,miscible with many organic solvents |
molecular formula: |
C6H12O |
structural formulas: |
MEK |
MIBK |
This method was evaluated according to the OSHA SLTC "Evaluation Guidelines for Air Sampling Methods Utilizing
Chromatographic Analysis"8. The Guidelines define analytical parameters, specify
required laboratory tests, statistical calculations and acceptance criteria. The analyte air concentrations
throughout this method are based on the recommended sampling and analytical parameters. Air concentrations listed in
ppm are referenced to 25°C and 101.3 kPa (760 mmHg).
1.2 Limit defining parameters
1.2.1 Detection limit of the analytical procedure
The detection limits of the analytical procedure are 4.90 pg for MEK and 3.13 pg for MIBK. These are the amounts
of analyte that will give a detector response that is significantly different from the response of a reagent blank.
(Section 4.1)
1.2.2 Detection limit of the overall procedure
The detection limits of the overall procedure are shown in Table 1.2.2. These are the amounts of analytes spiked
on the respective sampler that will give detector responses that are significantly different from the responses of
respective sampler blanks. (Section 4.2)
Table 1.2.2 Detection Limits of the Overall Procedure |
|
|
MEK
|
|
MIBK
|
sampler |
ng |
ppb |
µg/m3 |
|
ng |
ppb |
µg/m3 |
|
SKC CMS
SKC 575-002
3M 3520 |
244 388 230 |
7 33 10 |
20 96 29 |
|
129 376 281 |
3 28 11 |
11 115 43 |
|
1.2.3 Reliable quantitation limit
The reliable quantitation limits are shown in Table 1.2.3. These are the amounts of analytes spiked on the
respective samplers that will give detector responses that are considered the lower limits for precise
quantitative measurements. (Section 4.2)
Table 1.2.3 Reliable Quantitation Limits |
|
|
MEK
|
|
MIBK
|
sampler |
ng |
ppb |
µg/m3 |
EE |
|
ng |
ppb |
µg/m3 |
EE |
|
SKC CMS
SKC 575-002
3M 3520 |
813 1295 766 |
23 109 33 |
68 320 98 |
98.5 90.4 105.3 |
|
430 1255 937 |
9 94 35 |
36 384 144 |
111.7 81.0 86.4 |
EE is extraction efficiency |
1.2.4 Instrument calibration
The standard errors of estimate are 64 µg/sample for MEK and 47 µg/sample for MIBK over the range of
1900 to 14250 µg/sample for MEK and 1300 to 9753 µg/sample for MIBK. This range corresponds to 0.25 to 2
times the target concentration for SKC CMS sampling tubes. This is the sampler with the highest mass loading.
(Section 4.3)
1.2.5 Precision (Section 4.4)
SKC CMS sampling tubes
The precisions of the overall procedure at the 95% confidence level for the ambient temperature 15-day
storage test (at the target concentration) for SKC CMS tubes are ±11.7% for MEK, and ±11.5% for MIBK.
These precisions each include an additional 5% for sampling pump variability.
Diffusive samplers
The precisions of the overall procedure at the 95% confidence level for the ambient temperature 15-day
storage tests (at the target concentration) are shown in Table 1.2.5. There are different values given, depending on
whether both, either, or neither temperature (T) or atmospheric pressure (P) at the sampling site are
known. If the sampling site temperature is unknown, it is assumed to be 22.2 ± 15°C (72 ± 27°F)
and a variability of ±7.7% is included. If the atmospheric pressure is not known, it is estimated from the
sampling site elevation and a variability of ±3% is included. Each 3M precision value includes an additional
7.4% for sampling rate variation, and each SKC value an additional 8.7% also for sampling rate variation9.
Table 1.2.5 Precision of the Overall Procedure for Diffusive Samplers |
|
|
SKC 575-002 Passive Sampler
|
3M 3520 OVM
|
known condition |
MEK precision(±%) |
MIBK precision(±%) |
MEK precision(±%) |
MIBK precision(±%) |
|
both T&P
only T
only P
neither T nor P |
17.9 18.8 23.4 24.1 |
17.7 18.7 23.3 24.0 |
16.3 17.3 22.2 23.0 |
15.7 16.8 21.8 22.6 |
|
1.2.6 Recovery
The recovery of MEK and of MIBK from samples used in 15-day storage tests remained above those shown
in Table 1.2.6. (Section 4.5)
Table 1.2.6 Recovery (%) |
|
sampler |
storage temp |
MEK |
MIBK |
|
SKC anasorb CMS Tubes
SKC 575-002
3M 3520 |
ambient refrigerated ambient |
84.9 91.3 96.4 |
93.2 88.1 102.6 |
|
1.2.7 Reproducibility
Six samples for each of the three samplers evaluated in this method were collected from a controlled test
atmosphere and were submitted to OSHA SLTC for analysis. The samples were analyzed utilizing a draft copy of
this procedure for instruction. They were analyzed following 2 days of storage at 4°C. No individual
sample result deviated from its theoretical value by more than the precision reported in
Section 1.2.5. (Section 4.6)
2. Sampling Procedure
All safety practices that apply to the work area being sampled should be
followed. The sampling equipment should be attached to the worker in such a
manner that it will not interfere with work performance or safety.
2.1 Apparatus
2.1.1 SKC Anasorb CMS sampling tubes
Samples are collected with 7-cm × 4-mm i.d. × 6-mm o.d. glass sampling tubes packed with two sections
of SKC Anasorb CMS. The front section contains 150 mg and the back section contains 75 mg of CMS. The sections are
held in place with glass wool plugs. For this evaluation, commercially prepared Anasorb CMS sampling tubes were
purchased from SKC Inc. (catalog no. 226-121).
Samples are collected using a personal sampling pump calibrated, with the sampling device attached, to within
±5% of the recommended flow rate.
2.1.2 SKC 575-002 Passive Samplers and 3M 3520 OVMs
Samples are collected with either SKC 575-002 Passive Samplers, or with 3M 3520 OVMs. Samplers were
purchased from SKC, Inc. (catalog no. 575-002, contains one 500-mg section of Anasorb 747),
or from 3M (catalog no. 3520, contains two-sections with charcoal adsorbent pads).
A thermometer and a barometer are used to determine the sampling site air temperature and atmospheric pressure.
2.2 Reagents
None required.
2.3 Technique
2.3.1 SKC Anasorb CMS sampling tubes
Break off the ends of the flame-sealed sampling tube, to provide an opening approximately half the internal
diameter of the tube, immediately before sampling. Wear eye protection when breaking tube ends. Use
sampling-tube holders to reduce the hazard of broken sampling-tube ends to the employee. All tubes
should be from the same lot.
The smaller section of the sampling tube is used as a back-up and it is positioned nearest the sampling pump.
Attach the tube holder to the sampling pump with flexible non-crimping tubing. Position the sampler
in the worker's breathing zone so that the sampling tube is in an approximately vertical position with the inlet
facing down during sampling. Position the sampling pump, tube holder and tubing so they do not impede work
performance or safety.
Draw air to be sampled directly through the inlet of the tube holder. The air being sampled should not pass
through any hose or tubing before entering the sampling tube.
After sampling for the appropriate time, remove the sampling tube and seal it with plastic end caps. Seal each
sample end-to-end with an OSHA-21 form as soon as possible.
Submit at least one blank sample with each set of samples. Handle the blank sampler in the same manner as the
other samples except draw no air through it.
Record sample air volume (liters), sampling time (minutes) and sampling rate (mL/min) for each sample, along
with any potential interferences on the OSHA-91A form.
Submit the samples to the laboratory for analysis as soon as possible after sampling. Store the samples in a
refrigerator if a delay is unavoidable. Ship any bulk samples separate from the air samples.
2.3.2 SKC 575-002 Passive Samplers (In general, follow the manufacturer's instructions.)
Remove the sampler from the clear, air-tight bag just before sampling is to begin. CAUTION - The monitor
begins to sample immediately when it is removed from this bag. Keep the O-ring,
press-on cover, cover retainer, port plugs and PTFE tube for later use.
Record the start time on the sampler label and on the Form OSHA-91A.
Attach the sampler to the worker near his/her breathing zone with the perforations in the sampler facing forward.
Assure that the area directly in front of the sampler is unobstructed throughout the sampling period.
At the end of the sampling period, immediately detach the sampler from the worker and attach the cover with the
O-ring in place onto the sampler using the cover retainer. Visually inspect the O-ring
to be sure it is forming a proper seal around the entire circumference of the sampler. Record the stop time
on sampler label and on OSHA-91A form.
Prepare a blank by removing an unused sampler from its clear package and immediately attaching a cover with the
O-ring in place onto it.
Seal each sampler with an OSHA-21 form.
Verify that the sampling times are properly recorded on the OSHA-91A form for each sample. Also, identify blank
samples on this form.
Record the sampling site temperature and atmospheric pressure on the Form OSHA-91A.
List any compounds that could be considered potential interferences, especially solvents, that are being used in
the sampling area.
Submit the samples to the laboratory for analysis as soon as possible after sampling. Store the samples in a
refrigerator if a delay is unavoidable. Include all port plugs and PTFE tubes as they are used in the laboratory
analyses. Ship any bulk sample(s) in a container separate from the air samples.
2.3.3 3M OVMs (In general, follow the manufacturer's instructions supplied with the samplers.)
The monitors come individually sealed in small metal cans. Just before sampling is to begin, remove the plastic
lid from the can and lift up on the revealed ring. Pull back on the ring to open the can. Discard the metal top of
the can and remove the monitor. CAUTION - The monitor begins to sample immediately when the can is unsealed.
Keep the two closure caps with attached port plugs, cup and PTFE tubes in the can for later use. Close the can
with the plastic lid.
Record the start time on the back of the monitor and on the OSHA-91A form.
Attach the monitor to the worker near his/her breathing zone with the white face forward. Assure that the area
directly in front of the sampler is unobstructed throughout the sampling period. Do not remove the white film and
ring from the monitor until the sampling period is terminated.
At the end of the sampling period, detach the monitor from the worker and remove the white film and retaining
ring. Immediately snap a closure cap onto the primary (top) section of the monitor (where the white film and ring
were removed). It is critical that this step be done as quickly as possible because the sampling rate is more than
five times greater without the white film in place. This can be an important consideration, especially for
short-term sampling. Assure that the attached port plugs are placed firmly into the port holes.
The white film and ring can be discarded. Record the stop time on the back of the monitor and on the
OSHA-91A form.
The following steps should be performed in a low background (uncontaminated) area for a set of monitors as soon
as possible after sampling.
Prepare a blank by removing a new sampler from its can. Immediately remove the white film and ring and then
immediately attach a closure cap onto the unused monitor.
For each monitor (one at a time), separate the primary (top) and secondary (bottom) sections of the monitor
using the edge of a coin as a pry.
Securely snap a cup onto the bottom of the primary section.
Snap a closure cap onto the secondary section of the monitor and assure that the attached port plugs are placed
firmly into the port holes.
Return the sampler sections with closure caps and cup in place to the metal can containing the PTFE tubes (which
will be used by the laboratory). Close the can with the plastic lid, and seal it with an OSHA-21 form.
Verify that the sampling times are properly recorded on OSHA-91A form for each sample. Also, identify blank
samples on this form.
Record the sampling site temperature and atmospheric pressure on the OSHA-91A form.
List any compounds that could be considered potential interferences, especially solvents, that are being used in
the sampling area.
Submit the samples to the laboratory for analysis as soon as possible after sampling. Store the samples in a
refrigerator if a delay is unavoidable. Ship any bulk sample separate from the air samples.
2.4 Sampler capacity (Section 4.7)
2.4.1 The sampling capacity of the front sections of SKC Anasorb CMS sampling tubes was tested by sampling a
dynamically generated test atmosphere of MEK and MIBK (1131 mg/m3 or 384 ppm MEK, and
774 mg/m3, or 189 ppm MIBK) at an absolute humidity of 13.9 milligrams of water per liter of air
(74% relative humidity at 22°C). The samples were collected at 50 mL/min. The 5% breakthrough sampling time
for MEK was determined to be 300 min. No breakthrough of MIBK was observed, even after samples were collected
for 600 min.
Table 2.4.2 Sampling Rates (mL/min) at 760 mmHg and 298.2 K |
|
|
MEK |
MIBK |
|
SKC 575-002 3M 3520 |
16.88 32.59 |
13.62 27.00 |
|
2.4.2 The sampling rate and capacity of SKC 575-002 Passive Samplers and of 3M 3520 OVMs were
determined by sampling from atmospheres of MEK and MIBK at about two times their respective target concentrations
and at an absolute humidity of 16.4 milligrams of water per liter of air (about 80% relative humidity at 23°C)
for increasing time intervals. The sampling rates are shown in Table 2.4.2. A recommenced sampling time of 240 min
was obtained from this test.
2.5 Extraction efficiency (Section 4.8)
It is the responsibility of each analytical laboratory to determine extraction efficiency in-house
because the adsorbent material, internal standard, reagents and laboratory techniques could be different than those
used in this evaluation and they could influence analytical results.
The mean extraction efficiencies of MEK and MIBK from dry media over the range of the RQL to 2 times the target
concentrations are shown in Table 2.5. The extraction efficiency for MEK was affected by the presence of water.
This effect was caused by the instability of MEK on wet carbon-based sorbents. MIBK was not affected by
the presence of water.
Table 2.5 Extraction Efficiency Summary |
|
|
MEK
|
|
MIBK
|
medium |
RQL(µg) |
2×(µg) |
EE(%) |
|
RQL(µg) |
2×(µg) |
EE(%) |
|
Anasorb CMS SKC 575-002 3M 3520 OVM |
0.81 1.28 0.76 |
14250 4750 9500 |
100.3 92.2 98.0 |
|
0.42 1.27 0.94 |
9753 2601 5201 |
102.3 92.9 96.5 |
|
Extracted MEK samples with punctured septa gave results more than 10% lower than MEK samples with intact septa
upon standing in an autosampler rack for a day. The loss was attributed to volatility of MEK, room temperature, and
septa condition rather than chemical reactivity of MEK.
Extracted MEK samples with punctured septa remained stable for 12 h. Extracted MIBK samples with punctured septa
remained stable for at least a day. Extracted samples for both MEK and MIBK with intact septa remained stable for
at least a day.
2.6 Recommended sampling time and sampling rate
2.6.1 SKC Anasorb CMS sampling tubes
Sample for up to 240 min at 50 mL/min (12 L) when using SKC Anasorb CMS sampling tubes to collect TWA
(long-term) samples.
Sample for 5 min at 50 mL/min (0.25 L) when using SKC Anasorb CMS sampling tubes to collect ceiling
(short-term) samples.
When short-term samples are collected, the air concentration equivalent to the reliable quantitation limit
becomes larger. For example, the reliable quantitation limit for SKC Anasorb CMS sampling tubes is 1.1 ppm
(3.25 mg/m3) for MEK when 0.25 L is sampled.
2.6.2 SKC 575-002 Passive Samplers and 3M 3520 OVMs
Table 2.6.2 Sampling Rates(mL/min) at 760 mmHg and 298.2 K |
|
|
MEK |
MIBK |
|
SKC 575-002 3M 3520 |
16.88 32.59 |
13.62 27.00 |
|
Sample for up to 240 min when using SKC 575-002 Passive Samplers and 3M 3520 OVMs to collect TWA
(long-term) samples.
Sample for 5 min when using SKC 575-002 Passive Samplers and 3M 3520 OVMs to collect ceiling
(short-term) samples.
When short-term samples are collected, the air concentration equivalent to the reliable quantitation limit
becomes larger. For example, the reliable quantitation limit for 3M 3520 OVMs is 1.6 ppm (4.70 mg/m3)
for MEK when 0.163 L is sampled.
2.7 Interferences, sampling (Section 4.9)
2.7.1 Active sampler
Retention efficiency
Table 2.7.1.1 Mean Recovery |
|
MEK(%) |
MIBK(%) |
|
95.6 |
97.2 |
|
Six SKC Anasorb CMS sampling tubes were used to sample a test atmosphere containing two times the target
concentrations of MEK and of MIBK for one hour. Three samples were removed and analyzed after the initial one hour,
and the remaining three were used to sample contaminant-free air for an additional three hours
(four hours total). The absolute humidity of the test atmosphere was 14.6 milligrams of water per liter of air
(77.8% relative humidity at 21.4°C). The percent of the four-hour sample means relative to the
one-hour sample means are shown in Table 2.7.1.1. MEK and MIBK were efficiently retained following
collection.
Low humidity
Three SKC Anasorb CMS sampling tubes were used to sample a test atmosphere containing two times the target
concentrations of MEK and of MIBK. The absolute humidity of the test atmosphere was 2.7 milligrams of water
per liter of air (13.2% relative humidity at 22.6°C). The recovery for all samples was more than 95.1% of
theoretical for MEK and 98.2% of theoretical for MIBK. Low humidity had no significant effect on recovery.
Low concentration
Three SKC Anasorb CMS sampling tubes were used to sample a test atmosphere containing 0.1 times the target
concentrations of MEK and of MIBK. The absolute humidity of the test atmosphere was 15.5 milligrams of water per
liter of air (79.7% relative humidity at 22.3°C). The recovery for all samples was more than 94.9% of
theoretical for MEK and 101.1% of theoretical for MIBK. Low concentration had no significant effect on recovery.
Sampling interferences
Three Anasorb CMS sampling tubes were used to sample a test atmosphere containing one times the target
concentrations of MEK and of MIBK; and 553.3 mg/m3 of acetone, 253.7 mg/m3 of isopropyl
alcohol, 190.1 mg/m3 of toluene, 92.5 mg/m3 of xylene isomers, and 16.3 mg/m3
of ethyl benzene. The absolute humidity was 15.6 milligrams of water per liter of air (79.0% relative humidity
at 22.3°C). The recovery for all samples was more than 99.0% of theoretical for MEK and 102.2% of
theoretical for MIBK. The sampling interferences had no significant effect on recovery.
2.7.2 Diffusive samplers
Reverse diffusion
Table 2.7.2.1 Mean Recovery |
|
SKC 575-002
|
3M 3520
|
MEK(%) |
MIBK(%) |
MEK(%) |
MIBK(%) |
|
99.3 |
100.0 |
96.0 |
98.6 |
|
Six SKC 575-002 and six 3M 3520 samplers were used to test for reverse diffusion by first exposing
the samplers to a test atmosphere containing two times the target concentrations of MEK and of MIBK for one hour.
Three of each sampler were analyzed after the initial exposure, and the remaining three of each sampler were
exposed to contaminant-free air for an additional three hours (four hours total). The absolute
humidity of the test atmosphere was 14.6 milligrams of water per liter of air (77.8% relative humidity at
21.4°C). The percent of the means of the four hour samples relative to the one hour sample means are shown
in Table 2.7.2.1. Reverse diffusion was not significant.
Low humidity
Table 2.7.2.2 Low Humidity (% recovery) |
|
analyte |
SKC 575-002 |
3M 3520 |
|
MEK MIBK |
92.2 102.5 |
92.9 101.0 |
|
Three SKC and three 3M diffusive samplers were used to sample a test atmosphere containing two times the target
concentrations of MEK and of MIBK. The absolute humidity of the test atmosphere was 2.7 milligrams of water per
liter of air (13.2% relative humidity at 22.6°C). The lowest recoveries for all samplers are shown in Table
2.7.2.2. Low humidity had no significant effect on recovery.
Low concentration
Table 2.7.2.3 Low Concentration (% recovery) |
|
analyte |
SKC 575-002 |
3M 3520 |
|
MEK MIBK |
90.3 96.8 |
89.8 95.0 |
|
Three SKC and three 3M diffusive samplers were used to sample a test atmosphere containing 0.1 times the target
concentrations of MEK and of MIBK. The absolute humidity of the test atmosphere was 15.5 milligrams of water per
liter of air (79.7% relative humidity at 22.3°C). The lowest recoveries for all samplers are shown in Table
2.7.2.3. Low concentration had no significant effect on recovery.
Sampling interferences
Table 2.7.2.4 Sampling Interferences (% recovery) |
|
analyte |
SKC 575-002 |
3M 3520 |
|
MEK MIBK |
97.6 102.2 |
93.5 101.8 |
|
Three SKC and three 3M diffusive samplers were used to sample a test atmosphere containing one times the target
concentrations of MEK and of MIBK; and 553.3 mg/m3 of acetone, 253.7 mg/m3 of isopropyl
alcohol, 190.1 mg/m3 of toluene, 92.5 mg/m3 of xylene isomers, and 16.3 mg/m3 of
ethyl benzene. The absolute humidity was 15.6 milligrams of water per liter of air (79.0% relative humidity at
22.3°C). The lowest recoveries for all samplers are shown in Table 2.7.2.4. The sampling interferences had no
significant effect on recovery.
3. Analytical Procedure
Adhere to the rules set down in your Chemical Hygiene Plan10.
Avoid skin contact
and inhalation of all chemicals and review all appropriate MSDSs before beginning this analytical procedure.
3.1 Apparatus
3.1.1 A GC equipped with a flame ionization detector (FID). A Hewlett-Packard Model 5890 Series II GC equipped
with a ChemStation, an automatic sample injector, and an FID were used in this evaluation.
3.1.2 A GC column capable of separating MEK and MIBK from the extraction solvent, internal standards, and
potential interferences. A J&W Scientific 60-m × 0.32-mm i.d. DB-Wax
(0.5-µm df) capillary column was used in this evaluation.
3.1.3 An electronic integrator or other suitable means of measuring GC detector response. A Waters Millennium
Chromatography Manager system was used in this evaluation.
3.1.4 Two and four-milliliter glass vials with PTFE-lined septum caps.
3.1.5 One and two-milliliter volumetric pipets.
3.1.6 An SKC Desorption Shaker with rack (226D-03K) was used to extract SKC 575-002 Passive
Samplers in this evaluation.
3.2 Reagents
3.2.1 2-Butanone (methyl ethyl ketone, MEK) [CAS no. 78-93-3], reagent grade or better. The MEK used in this
evaluation was 99+% A.C.S. Reagent grade (lot no. 11619CX) purchased from Aldrich (Milwaukee, WI).
3.2.2 Hexone (methyl isobutyl ketone, MIBK) [CAS no. 108-10-1], reagent grade or better. The MIBK used in this
evaluation was Analytical Reagent grade (lot no. CVT) purchased from Mallinckrodt (St. Louis, MO)
3.2.3 Carbon disulfide (CS2), [CAS no. 75-15-0], reagent grade or better. The carbon disulfide used
in this evaluation was 99.9+% low benzene content grade (lot no. 1054JQ) purchased from Aldrich (Milwaukee, WI).
3.2.4 N,N-Dimethyl formamide (DMF) [CAS no. 68-12-2], reagent grade or better. The DMF used in this
evaluation was Certified A.C.S. grade (lot no. 902902) purchased from Fisher (Fair Lawn, NJ).
3.2.5 1-Phenylhexane (hexylbenzene) [CAS no. 1077-16-3], reagent grade or better. The 1-phenylhexane
used in this evaluation was 97% reagent grade (lot no. 03006PZ) purchased from Aldrich (Milwaukee, WI).
3.2.6 The extraction solvent used for this evaluation consisted of 1% DMF in CS2.
1-Phenylhexane (1 µL/mL) was added to the solution for use as an internal standard. Other internal
standards can be used provided they are fully tested.
3.3 Standard preparation
3.3.1 Prepare concentrated stock standards by weighing 3 mL of MEK and/or 2 mL of MIBK into a 5-mL
volumetric flask, and diluting to the mark with CS2. Obviously, no CS2 addition is necessary
if both MEK and MIBK are added to the same flask. Prepare working analytical standards by injecting microliter
amounts of concentrated stock standards into vials containing either 1 or 2 mL of extracting solution delivered
from the same dispenser used to extract samples. For example, to prepare a target level standard to analyze SKC
Anasorb CMS sampling tubes, inject 15 µL of a stock solution containing 480 mg/mL of MEK and 320 mg/mL MIBK
into 1 mL of extracting solution.
3.3.2 Bracket sample concentrations with standard concentrations. If, upon analysis, sample concentrations fall
outside the range of prepared standards, prepare and analyze additional standards to confirm instrument response,
or dilute high samples with extraction solvent and reanalyze the diluted samples.
3.4 Sample preparation
3.4.1 SKC Anasorb CMS sampling tubes
Remove the plastic end caps from the sample tube and carefully transfer each section of the adsorbent to separate
2-mL vials. Discard the glass tube and glass wool plugs.
Add 1.0 mL of extracting solution to each vial and immediately seal the vials with
polytetrafluoroethylene-lined caps.
Shake the vials vigorously several times during the 60 min extraction time.
3.4.2 SKC 575-002 Passive Samplers (In general, follow the manufacturer's instructions.)
Cut off the ends of the two protruding tubes (ports) of each sampler with a razor blade or sharp knife.
Slowly and carefully add 2.0 mL of extraction solvent through the protruding tube (port)
nearest the outside edge of the sampler.
Immediately insert plugs into the ports.
Mount the samplers in the sampler rack (SKC Cat. No. 226-04-5) of a specialized shaker (SKC Cat. No. 226D-03-1)
and shake the samplers for 1 hour.
Do not leave the extracted sample in the sampler. Transfer each extracted sample by removing the plugs from the
sampler ports, firmly inserting the tapered end of a supplied PTFE tube into the outer port, and carefully pouring
the solution through the PTFE tube into a labeled autosampler vial. Immediately cap each vial.
3.4.3 3M 3520 OVMs (In general, follow the manufacturer's instructions.)
Remove both sampler sections from the metal cans, along with the sections of PTFE tubing. Assure that the closure
caps are firmly snapped to the primary and secondary sections of all the samplers. Also assure that all cap plugs
are firmly seated in the cap ports. Any deviations must be noted.
Prepare one section of the sampler at a time by temporarily removing the cap plugs from the ports and adding
2.0 mL of extraction solvent through the center port.
Allow the sampler sections to extract for one hour. Apply gentle agitation to the sampler sections, periodically,
during the extraction period.
Do not leave the extracted sample in the sampler. Transfer the solution from each sampler section by removing
both plugs from the ports, firmly inserting a decanting spout (a small section of PTFE tubing) into the outer port
and carefully pouring the liquid through the spout into a labeled autosampler vial. Immediately cap each vial.
3.5 Analysis
3.5.1 Analytical conditions
GC conditions
|
|
column temperature: |
initial 40°C, hold 1 min, program at 4°C/min to 140°C, hold until column is clear. |
zone temperatures: |
220°C (injector) 220°C (detector) |
run time: | 26 min |
column gas flow: |
4.9 mL/min (hydrogen) |
septum purge: |
3.3 mL/min (hydrogen) |
injection size: |
1.0 µL (26:1 split) |
column: |
60-m × 0.32-mm i.d. capillary J&W DB-Wax (0.5-µm df) |
retention times: |
4.1 min (MEK)
6.3 min (MIBK)
23.4 min (1-phenylhexane) |
FID conditions
|
hydrogen flow: |
35 mL/min |
air flow: | 450 mL/min |
nitrogen makeup flow: |
37 mL/min |
Figure 3.5.1. Chromatogram obtained at the target concentrations with the recommended conditions.
(1- CS2; 2- MEK; 3- MIBK; 4- DMF; 5- 1-phenylhexane) |
3.5.2 An internal standard (ISTD) calibration method is used. A calibration curve can be constructed by plotting
ISTD-corrected response of standard injections versus micrograms of analyte per sample. Bracket the
samples with freshly prepared analytical standards over a range of concentrations.
Figure 3.5.2.1. Calibration curve for MEK |
|
Figure 3.5.2.2. Calibration curve for MIBK |
3.6 Interferences (analytical)
3.6.1 Any compound that produces an FID response and has a similar retention time as the analyte or internal
standard is a potential interference. If any potential interferences were reported, they should be considered before
samples are extracted. Generally, chromatographic conditions can be altered to separate an interference from the
analyte.
3.6.2 When necessary, the identity of an analyte peak can be confirmed with additional analytical data
(Section 4.9).
3.7 Calculations
3.7.1 SKC Anasorb CMS sampling tubes
The amount of MEK and/or MIBK per sample is obtained from the appropriate calibration curve in terms of
micrograms per sample, uncorrected for extraction efficiency. The back section is analyzed primarily to determine
the extent of sampler saturation. If any analyte is found on the back section, it is added to the amount on the
front section. This total amount is then corrected by subtracting the total amount (if any) found on the blank.
The air concentration is calculated using the following formulas.
|
where: |
CM |
is concentration by weight (mg/m3) |
M | is micrograms per sample |
V | is liters of air sampled |
EE | is extraction efficiency, in decimal form |
|
|
|
where: |
CV | is concentration by volume (ppm)
|
VM
|
is molar volume at 25°C and 760 mmHg (NTP) |
CM | is concentration by weight |
Mr | is molecular weight (MEK = 72.10, MIBK = 100.16) |
|
3.7.2 Diffusive samplers
Table 3.7.2 Sampling Rates (mL/min) at 760 mmHg and 298.2 K (NTP) |
|
|
MEK |
MIBK |
|
SKC 575-002 3M 3520 |
16.88 32.59 |
13.62 27.00 |
|
The amount of MEK and/or MIBK for the samples is obtained from the appropriate calibration curve in terms of
micrograms per sample, uncorrected for extraction efficiency. The 3M 3520 is a two-section sampler and the back
section is analyzed primarily to determine the extent of sampler saturation. If any analyte is found on the back
section, the amount is multiplied by 2.2 (as per manufacturer's instructions) and then added to the amount on the
front section. The total amount is then corrected by subtracting the total amount (if any) found on the blank. The
air concentration is calculated using the following formulas.
RSS |
= |
RNTP |
( |
Tss |
) |
3/2 |
( |
PNTP |
) |
|
|
TNTP |
PSS |
|
where |
RSS |
is the sampling rate at sampling site |
RNTP |
is the sampling rate at NTP |
TSS |
is the sampling site temperature in K |
TNTP |
is 298.2 K |
PSS |
is the sampling site pressure in mmHg |
PNTP |
is 760 mmHg |
|
|
|
where |
CM | is concentration by weight (mg/m3) |
M | is micrograms per sample |
RSS | is the sampling rate at the sampling site |
t | is the sampling time |
EE | is extraction efficiency, in decimal form |
|
|
|
where |
CV |
is concentration by volume (ppm) |
VM |
is molar volume at NTP |
CM |
is concentration by weight |
Mr |
is molecular weight (MEK = 72.10, MIBK = 100.16) |
|
If the sampling site temperature is not provided, assume that it is 22.2 °C. If the sampling site atmospheric
pressure is not given, calculate an approximate value based on the sampling site elevation from the following
equation.
PSS = AE2 - BE + 760.0 |
where |
PSS | is the approximate atmospheric pressure |
E | is the sampling site elevation, ft |
A | is 3.887×10-7 mmHg/ft2 |
B | is 0.02748 mmHg/ft |
|
4. Backup Data
General background information about the determination of detection limits and precision of the overall procedure
is found in the "Evaluation Guidelines for Air Sampling Methods Utilizing Chromatography Analysis"11. The Guidelines define analytical parameters, specific laboratory tests, statistical
calculations and acceptance criteria.
4.1 Detection limit of the analytical procedure (DLAP)
DLAP is measured as the mass of analyte introduced onto the chromatographic column. Ten analytical standards were
prepared with equal increments with the highest standard containing 475 ng/mL of MEK and 553 ng/mL of MIBK. These are
concentrations that would produce peaks approximately 10 times the response of a reagent blank near the elution times
of the analytes. These standards, and the reagent blank were analyzed with the recommended analytical parameters
(1-µL injection with a 26:1 split), and the data obtained were used to determine the required parameters
(standard error of estimate and slope) for the calculation of the DLAP. The DLAP for MEK was 4.90 pg and it was
3.13 pg for MIBK.
Table 4.1.1 Detection Limit of the Analytical Procedure for MEK |
|
concentration (ng/mL) |
mass on column (pg) |
area counts (µV-s) |
|
0 48 95 142 190 238 285 332 380 428 475 |
0 1.8 3.6 5.5 7.3 9.2 11.0 12.8 14.6 16.5 18.3 |
0 16 28 35 43 60 40 70 74 83 96 |
|
|
Figure 4.1.1 Plot of data used to determine the DLAP for MEK. |
|
Table 4.1.2 Detection Limit of the Analytical Procedure for MIBK |
|
concentration (ng/mL) |
mass on column (pg) |
area counts (µV-s) |
|
0 33 98 163 228 293 358 390 423 488 553 |
0 1.3 3.8 6.3 8.8 11.3 13.8 15.0 16.3 18.8 21.3 |
0 12 23 45 55 68 90 90 92 99 132 |
|
|
Figure 4.1.2 Plot of data used to determine the DLAP for MIBK. |
4.2 Detection limit of the overall procedure (DLOP) and reliable quantitation limit (RQL)
DLOP is measured as mass per sample and expressed as equivalent air concentrations, based on the recommended
sampling parameters. Ten samplers were spiked with descending increments of analyte. The highest amount shown in
the following tables is the amount spiked on a sampler that would produce a peak approximately 10 times the
response of a sample blank. These spiked samplers, and the sample blanks were analyzed with the recommended
analytical parameters, and the data obtained used to calculate the required parameters (standard error of
estimate and the slope) for the calculation of the DLOP.
Table 4.2 Detection Limits of the Overall Procedure |
|
|
MEK
|
|
MIBK
|
sampler |
ng |
ppb |
µg/m3 |
|
ng |
ppb |
µg/m3 |
|
SKC CMS SKC Anasorb 747 SKC 575-002 3M 3520 |
244 291 388 230 |
7 8 33 10 |
20 24 96 29 |
|
129 329 376 281 |
3 7 28 11 |
11 27 115 43 |
|
Table 4.2.1 DLOP/RQL for MEK Collected on SKC CMS Sampling Tubes |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 48 142 238 332 428 522 570 618 713 808 |
0 26 14 31 44 47 54 58 66 66 94 |
|
|
|
Figure 4.2.1 Plot of data to determine the DLOP/RQL for MEK collected on SKC CMS sampling tubes. |
|
Table 4.2.2 DLOP/RQL for MIBK Collected on SKC CMS Sampling Tubes |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 65 130 195 260 325 358 390 455 520 553 |
0 0 16 22 28 32 40 43 66 64 61 |
|
|
|
Figure 4.2.2 Plot of data to determine the DLOP/RQL for MIBK collected on SKC CMS sampling tubes. |
|
Table 4.2.3 DLOP/RQL for MEK Collected on SKC Anasorb 747 Sampling Tubes |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 190 380 570 665 760 855 1045 1235 1425 1615 |
0 11 18 25 31 36 42 46 57 68 93 |
|
|
|
Figure 4.2.3 Plot of data to determine the DLOP/RQL for MEK collected on SKC Anasorb 747 sampling tubes. |
|
Table 4.2.4 DLOP/RQL for MIBK Collected on SKC Anasorb 747 Sampling Tubes |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 130 260 390 455 520 585 715 845 975 1105 |
0 13 24 40 33 35 42 53 57 76 110 |
|
|
|
Figure 4.2.4 Plot of data to determine the DLOP/RQL for MIBK collected on SKC Anasorb 747 sampling tubes. |
|
Table 4.2.5 DLOP/RQL for MEK Collected on SKC 575-002 Passive Samplers |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 190 38 570 665 760 855 1045 1235 1425 1615 |
0 24 34 40 47 46 46 59 70 90 82 |
|
|
|
Figure 4.2.5 Plot of data to determine the DLOP/RQL for MEK collected on SKC 575-002 Passive Samplers. |
|
Table 4.2.6 DLOP/RQL for MIBK Collected on SKC 575-002 Passive Samplers |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 130 260 390 455 520 585 715 845 975 1105 |
0 11 21 28 29 40 39 66 77 55 79 |
|
|
|
Figure 4.2.6 Plot of data to determine the DLOP/RQL for MIBK collected on SKC 575-002 Passive Samplers. |
|
Table 4.2.7 DLOP/RQL for MEK Collected on 3M 3520 OVMs |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 95 285 475 665 855 1045 1140 1235 1425 1615 |
0 6 24 29 42 49 58 65 79 80 86 |
|
|
|
Figure 4.2.7 Plot of data to determine the DLOP/RQL for MEK collected on 3M 3520 OVMs. |
|
Table 4.2.8 DLOP/RQL for MIBK Collected on 3M 3520 OVMs |
|
mass per sample (ng) |
area counts (µV-s) |
|
0 65 195 325 455 585 715 780 845 975 1105 |
0 4 14 18 24 44 43 48 54 81 70 |
|
|
|
Figure 4.2.8 Plot of data to determine the DLOP/RQL for MIBK collected on 3M 3520 OVMs. |
The RQL is considered the lower limit for precise quantitative measurements. It is determined from the
regression line parameters obtained for calculation of the DLOP, providing the extraction efficiency
(EE) is 75% to 125%.
Table 4.2.9 Reliable Quantitation Limits |
|
|
MEK
|
|
MIBK
|
sampler |
ng |
ppb |
µg/m3 |
EE |
|
ng |
ppb |
µg/m3 |
EE |
|
SKC CMS SKC Anasorb 747 SKC 575-002 3M 3520 |
813 971 1295 766 |
23 27 109 33 |
68 81 320 98 |
98.5 101.5 90.4 105.3 |
|
430 1097 1255 937 |
9 22 94 35 |
36 91 384 144 |
111.7 98.2 81.0 86.4 |
|
Figure 4.2.9 Chromatogram of the RQL for MEK extracted from SKC Anasorb CMS sampling tubes. Peak 1 is MEK. |
|
Figure 4.2.10 Chromatogram of the RQL for MIBK extracted from SKC Anasorb CMS sampling tubes. Peak 1 is MIBK. |
|
Figure 4.2.11 Chromatogram of the RQL for MEK extracted from SKC Anasorb 747 sampling tubes. Peak 1 is MEK. |
|
Figure 4.2.12 Chromatogram of the RQL for MIBK extracted from SKC Anasorb 747 sampling tubes. Peak 1 is MIBK. |
|
Figure 4.2.13 Chromatogram of the RQL for MEK extracted from SKC 575-002 Passive Samplers. Peak 1 is MEK. |
|
Figure 4.2.14 Chromatogram of the RQL for MIBK extracted from SKC 575-002 Passive Samplers. Peak 1 is MIBK. |
|
Figure 4.2.15 Chromatogram of the RQL for MEK extracted from 3M 3520 OVM. Peak 1 is MEK. |
|
Figure 4.2.16 Chromatogram of the RQL for MIBK extracted from 3M 3520 OVM. Peak 1 is MIBK. |
4.3 Instrument Calibration
The standard errors of estimate were determined from the linear regressions of data points from standards over a
range that covers 0.25 to 2 times the target concentrations for SKC CMS sampling tubes. This was the sampler with the
highest mass loadings. Calibration curves were constructed and shown in Section 3.5.2 from the injections of the
fifteen standards. The standard errors of estimate are 64 µg/sample for MEK and 47 µg/sample for MIBK.
Table 4.3.1 Instrument Calibration for MEK |
|
standard concn (µg/sample) |
|
area counts (µV·s) |
|
1900 3800 7125 10450 14250 |
|
209059 382186 711627 1030541 1410615 |
203442 383631 702855 1028461 1414645 |
194603 389559 701446 1025964 1406129 |
|
Table 4.3.2 Instrument Calibration for MIBK |
|
standard concn (µg/sample) |
|
area counts (µV·s) |
|
1300 2601 4876 7152 9753 |
|
171450 313431 584366 845491 1157297 |
166556 313539 575873 842971 1161587 |
158962 319156 576681 839986 1153280 |
|
4.4 Precision (overall procedure)
4.4.1 SKC CMS sampling tubes
The precision at the 95% confidence level is obtained by multiplying the standard error of estimate by 1.96
(the z-statistic from the standard normal distribution at the 95% confidence level). In
Section 4.5,
95% confidence intervals are drawn about their respective regression
lines in the storage graph figures. Each precision includes an additional 5% for sampling error. The precisions of the overall
procedure at the 95% confidence interval for the ambient temperature 15-day storage tests (at the target
concentration) for MEK and for MIBK were ±11.7% and ±11.5%, respectively. These values are from the
standard error of estimates shown in figures
4.5.1.1 and 4.5.1.3.
4.4.2 Diffusive samplers
The precisions of the overall procedure at the 95% confidence level for the ambient temperature 15-day
storage tests (at the target concentration) are shown in Table 4.4.2. There are different values given, depending on
whether both, either, or neither temperature (T) or atmospheric pressure (P) at the sampling site are
known. If the sampling site temperature is unknown, it is assumed to be 22.2 ± 15°C (72 ± 27°F)
and a variability of ±7.7% is included. If the atmospheric pressure is not known, it is estimated from the
sampling site elevation and a variability of ±3% is included. Each 3M precision value includes an additional
7.4% for sampling rate variation, and each SKC value an additional 8.7%, also for sampling rate variation
12.
Table 4.4.2 Standard Error of Estimate and Precision of the overall
procedure for Diffusive Samplers |
|
|
SKC 575-002 Passive Sampler
|
|
3M 3520 OVM
|
|
MEK |
MIBK |
|
MEK |
MIBK |
known condition |
SEE (%) |
precision (±%) |
SEE (%) |
precision (±%) |
|
SEE (%) |
precision (±%) |
SEE (%) |
precision (±%) |
|
both T&P only T only P neither T nor P |
9.12 9.60 11.94 12.30 |
17.8 18.7 23.3 24.1 |
9.05 9.53 11.88 12.26 |
17.7 18.7 23.3 24.0 |
|
8.32 8.84 11.34 11.73 |
16.3 17.3 22.2 23.0 |
8.03 8.57 11.13 11.52 |
15.7 16.8 21.8 22.6 |
|
4.5 Storage tests
4.5.1 Active samples
Storage samples for MEK and MIBK were generated by sampling controlled test atmospheres with SKC CMS and with SKC
Anasorb 747 sampling tubes at 50 mL/min for four hours. The analyte concentrations of the test atmospheres were the
target concentrations with an absolute humidity of 14.3 milligrams of water per liter of air (77.2% at 21.1°C).
Thirty-three storage samples were collected with each sampler. Three of each sampler were analyzed on
the day of generation. Fifteen of each sampler were stored at reduced temperature (about 4°C) and the other
fifteen were stored in a closed drawer at ambient temperature (about 22°C). Three samples were selected from
each of the storage sets and analyzed at 2-4 day intervals. Sample results were not corrected for
extraction efficiency.
Table 4.5.1.1 Storage Tests for MEK on SKC CMS Sampling Tubes |
|
time (days) |
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
95.0 90.7 88.2 92.3 92.2 85.8 |
94.4 89.2 83.7 89.7 86.3 80.4 |
90.8 96.4 88.0 91.5 87.3 82.7 |
|
95.0 96.3 93.0 96.2 94.0 92.6 |
94.4 95.9 92.7 94.3 94.1 94.2 |
90.8 96.4 92.0 95.1 93.3 88.8 |
|
Table 4.5.1.2 Storage Tests for MIBK on SKC CMS Sampling Tubes |
|
time (days) |
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
96.1 92.7 91.0 96.6 96.7 95.1 |
95.3 91.4 89.7 94.6 94.4 88.5 |
92.6 97.5 88.0 96.5 95.1 90.6 |
|
96.1 96.3 95.2 96.3 95.3 95.5 |
95.3 96.1 94.6 96.4 95.9 97.2 |
92.6 95.9 93.1 97.0 96.0 96.0 |
|
Table 4.5.1.3 Storage Tests for MEK on SKC Anasorb 747 Sampling Tubes |
|
time (days) |
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
89.3 82.8 75.9 76.7 74.2 73.3 |
90.7 82.6 77.1 76.6 73.2 74.0 |
90.8 84.0 78.4 76.9 70.6 70.4 |
|
89.3 88.9 86.5 82.3 81.2 79.3 |
90.7 88.5 87.1 81.5 80.5 81.1 |
90.8 87.1 85.8 83.1 78.7 80.4 |
|
Table 4.5.1.4 Storage Tests for MIBK on SKC Anasorb 747 Sampling Tubes |
|
time (days) |
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
93.6 93.8 91.8 93.4 92.4 93.5 |
93.9 93.4 93.8 93.7 91.5 93.0 |
94.4 94.6 92.9 93.3 88.5 89.2 |
|
93.6 93.1 93.9 92.4 92.9 92.4 |
93.9 94.5 91.2 92.2 93.1 93.6 |
94.4 92.9 93.0 91.6 91.3 93.8 |
|
Figure 4.5.1.1 Ambient Storage for MEK collected on SKC CMS sampling tubes. |
|
Figure 4.5.1.2 Refrigerated Storage for MEK collected on SKC CMS sampling tubes. |
|
Figure 4.5.1.3 Ambient Storage for MIBK collected on SKC CMS sampling tubes. |
|
Figure 4.5.1.4 Refrigerated Storage for MIBK collected on SKC CMS sampling tubes. |
|
Figure 4.5.1.5 Ambient Storage for MEK collected on SKC Ansasorb 747 sampling tubes. |
|
Figure 4.5.1.6 Refrigerated Storage for MEK collected on SKC Anasorb 747 sampling tubes. |
|
Figure 4.5.1.7 Ambient Storage for MIBK collected on SKC Anasorb 747 sampling tubes. |
|
Figure 4.5.1.8 Refrigerated Storage for MIBK collected on SKC Anasorb 747 sampling tubes. |
4.5.2 Diffusive samplers
Storage samples for MEK and MIBK were generated by sampling controlled test atmospheres with SKC
575-002 Passive Samplers and with 3M 3520 OVMs for four hours. The analyte concentrations
of the test atmospheres were the target concentrations with an absolute humidity of 14.3 milligrams of
water per liter of air (77.2% at 21°C). Thirty-three storage samples were collected with each
sampler. Three of each sampler were analyzed on the day of generation. Fifteen of each sampler were stored at
reduced temperature (about 4°C) and the other fifteen were stored in a closed drawer at ambient temperature
(about 22°C). Three samples were selected from each of the storage sets and analyzed at 2-4
day intervals. Sample results were not corrected for extraction efficiency.
Table 4.5.2.1 Storage tests for MEK on SKC 575-002 Passive Samplers |
|
time (days) |
|
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
|
96.6 95.5 90.2 83.6 84.1 79.3 |
98.9 95.7 90.5 86.0 84.3 79.5 |
89.2 98.5 87.2 89.9 83.0 78.8 |
|
96.6 94.6 95.9 90.5 91.2 91.3 |
98.9 97.7 96.8 92.0 91.2 90.3 |
89.2 99.5 95.8 93.8 93.2 93.7 |
|
Table 4.5.2.2 Storage tests for MIBK on SKC 575-002 Passive Samplers |
|
time (days) |
|
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
|
96.9 96.6 92.1 89.9 89.3 84.8 |
99.2 95.9 93.2 93.0 89.7 85.1 |
89.8 97.0 88.1 92.5 89.3 85.7 |
|
96.9 94.3 95.2 86.7 89.9 87.5 |
99.2 96.7 95.0 91.4 89.6 87.6 |
89.8 98.4 93.9 93.0 90.5 89.4 |
|
Table 4.5.2.3 Storage Tests for MEK on 3M 3520 OVMs |
|
time (days) |
|
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
|
96.9 96.5 98.7 89.2 94.0 99.8 |
101.3 96.6 92.9 100.5 92.8 96.2 |
92.8 89.5 92.4 92.7 100.2 98.0 |
|
96.6 96.9 101.8 92.7 104.1 98.8 |
101.3 93.5 97.6 97.6 91.5 93.9 |
92.8 94.6 97.5 92.3 95.1 102.8 |
|
Table 4.5.2.4 Storage Tests for MIBK on 3M 3520 OVMs |
|
time (days) |
|
ambient storage recovery (%) |
|
refrigerated storage recovery (%) |
|
0 2 5 8 12 15 |
|
101.2 101.8 103.7 95.3 99.7 105.5 |
104.9 101.2 100.1 105.8 100.9 103.3 |
100.5 94.9 98.7 99.2 105.0 103.0 |
|
101.2 102.4 109.4 97.8 108.5 103.1 |
104.9 99.4 103.3 105.3 97.3 98.7 |
100.5 100.5 102.1 96.9 101.8 106.9 |
|
Figure 4.5.2.1 Ambient Storage for MEK collected on SKC 575-002 Passive Samplers. |
|
Figure 4.5.2.2 Refrigerated Storage for MEK collected on SKC 575-002 Passive Samplers. |
|
Figure 4.5.2.3 Ambient Storage for MIBK collected on SKC 575-002 Passive Samplers. |
|
Figure 4.5.2.4 Refrigerated Storage for MIBK collected on SKC 575-002 Passive Samplers. |
|
Figure 4.5.2.5 Ambient storage for MEK collected on 3M 3520 OVMs. |
|
Figure 4.5.2.6 Refrigerated storage for MEK collected on 3M 3520 OVMs. |
|
Figure 4.5.2.7 Ambient storage for MIBK collected on 3M 3520 OVMs. |
|
Figure 4.5.2.8 Refrigerated storage for MIBK collected on 3M 3520 OVMs. |
4.6 Reproducibility
Six samples for each of the three samplers evaluated in this method were collected from a controlled test
atmosphere and were submitted to OSHA SLTC for analysis. The concentration of the test atmosphere was
593.46 mg/m3 for MEK and 393.68 mg/m3 for MIBK. The absolute humidity was 16.9
milligrams of water per liter of air (77.8% RH at 24°C). The face velocity of the sampled air was
0.4 m/s. The samples were analyzed utilizing a draft copy of this procedure for analyst instruction.
The samples were analyzed after being stored for 2 days at 4°C. Sample results were corrected for
extraction efficiency. No sample result for either analyte had a deviation greater than the precision of the
overall procedure determined in Section 4.4.
Table 4.6.1 Reproducibility Data for MEK and MIBK Collected on SKC CMS Sampling Tubes |
|
MEK
|
|
MIBK
|
theoretical (µg/sample) |
recovered (µg/sample) |
recovery (%) |
deviation (%) |
|
theoretical (µg/sample) |
recovered (µg/sample) |
recovery (%) |
deviation (%) |
|
7157.1 6991.0 7151.2 6688.3 7353.0 6991.0 |
6715.1 6514.4 6551.4 6101.4 6743.1 6570.5 |
93.8 93.2 91.6 91.2 91.7 94.0 |
-6.2 -6.8 -8.4 -8.8 -8.3 -6.0 |
|
4747.8 4367.6 4743.8 4436.8 4877.7 4637.6 |
4508.6 4388.5 4331.7 4137.9 4379.1 4399.1 |
95.0 100.5 91.3 93.3 89.8 94.9 |
-5.0 0.5 -8.7 -6.7 -10.2 -5.1
|
|
Table 4.6.2 Reproducibility Data for MEK and MIBK Collected on SKC 575-002 Passive Samplers |
|
MEK
|
|
MIBK
|
theoretical (µg/sample) |
recovered (µg/sample) |
recovery (%) |
deviation (%) |
|
theoretical (µg/sample) |
recovered (µg/sample) |
recovery (%) |
deviation (%) |
|
2772.7 2772.7 2772.7 2772.7 2772.7 2772.7 |
2719.3 3062.3 2818.2 2720.2 2738.9 2688.3 |
98.1 110.4 101.6 98.1 98.8 97.0 |
-1.9 10.4 1.6 -1.9 -1.2 -3.0 |
|
1484.1 1484.1 1484.1 1484.1 1484.1 1484.1 |
1548.1 1729.8 1602.4 1558.0 1598.7 1559.5 |
104.3 116.6 108.0 105.0 107.7 105.1 |
4.3 16.6 8.0 5.0 7.7 5.1 |
|
Table 4.6.3 Reproducibility Data for MEK and MIBK Collected on 3M 3520 OVMs |
|
MEK
|
|
MIBK
|
theoretical (µg/sample) |
recovered (µg/sample) |
recovery (%) |
deviation (%) |
|
theoretical (µg/sample) |
recovered (µg/sample) |
recovery (%) |
deviation (%) |
|
5353.1 5353.1 5353.1 5353.1 5353.1 5353.1 |
5430.2 5398.6 5469.8 5488.4 5112.4 4725.2 |
101.4 100.9 102.2 102.5 95.5 88.3 |
1.4 0.9 2.2 2.5 -4.5 -11.7 |
|
2942.0 2942.0 2942.0 2942.0 2942.0 2942.0 |
3194.7 3171.8 3193.9 3216.8 3102.2 2957.9 |
108.6 107.8 108.6 109.3 105.4 100.5 |
8.6 7.8 8.6 9.3 5.4 0.5 |
|
4.7 Sampler capacity
4.7.1 SKC Anasorb CMS sampling tubes
The sampling capacity of the front section of SKC Anasorb CMS sampling tubes was tested by sampling from a
dynamically generated test atmosphere of 1131 mg/m3 (384 ppm) MEK and 774 mg/m3 (189 ppm)
MIBK with an absolute humidity of 13.9 milligrams of water per liter of air (74% relative humidity at 22°C).
Four samples were collected at about 50 mL/min. CMS sampling tubes were placed in-line behind the front test
sections and they were changed every 15 min after initial collection for four hours. Five-percent
breakthrough for MEK occurred after 15 L of air had been sampled. This air volume is that which would be collected
in a 5-h air sample. Breakthrough of MIBK was never observed in any of the sampler capacity tests in
which samples were collected for as long as ten hours. The recommended sampling time for SKC Anasorb CMS sampling
tubes is 4 hours. This sampling time provides a considerable capacity safety margin for MEK because of the
presence of MIBK in the test atmosphere.
Figure 4.7.1 Five percent breakthrough air volume for MEK from SKC Anasorb CMS |
Table 4.7.1 Breakthrough of MEK from SKC Anasorb CMS |
|
test no. |
air vol. (L) |
sampling time (min) |
downstream concn (mg/m3) |
breakthrough (%) |
|
1 |
11.97 12.72 13.47 14.22 14.96 15.71 16.46 17.21 17.96 |
240 15 15 15 15 15 15 15 15 |
0.0 0.0 0.0 6.7 25.8 73.4 212.3 493.1 915.6 |
0.0 0.0 0.0 0.6 2.3 6.5 18.8 43.6 81.0 |
|
2 |
11.70 12.43 13.17 13.90 14.63 15.36 16.09 16.82 17.55 |
240 15 15 15 15 15 15 15 15 |
0.0 0.0 0.0 0.0 7.7 33.3 117.9 286.4 625.8 |
0.0 0.0 0.0 0.0 0.7 2.9 10.4 25.3 55.3 |
|
3 |
12.09 12.84 13.60 14.35 15.11 15.86 16.82 17.37 18.13 |
240 15 15 15 15 15 15 15 15 |
0.0 0.0 9.2 44.3 11.5 211.5 360.6 613.2 879.8 |
0.0 0.0 0.8 3.9 1.0 18.7 31.9 54.2 77.8 |
|
4 |
11.21 11.91 12.61 13.31 14.01 14.71 15.41 16.11 16.81 |
240 15 15 15 15 15 15 15 15 |
0.0 0.0 4.2 12.0 35.7 84.9 153.1 326.8 598.4 |
0.0 0.0 0.4 1.1 3.2 7.5 13.5 28.9 52.9 |
|
4.7.2 Diffusive samplers
Sampling rate and sampler capacity were determined using SKC and 3M samplers that were exposed to a controlled
test atmosphere for increasing time intervals. Three of each sampler were exposed for each time interval. Sampler
capacity is defined as exceeded when the sampling rate appears to decrease, as was the case for MEK collected on
3M 3520 OVMs. The concentration of the test atmospheres was about two times the target concentration with an
absolute humidity of about 16.4 milligrams of water per liter of air (80% RH at 23°C). Preliminary sampling
rates were determined by averaging the values for the 0.5, 1 and 2 h samples. Horizontal lines were placed 10%
above and 10% below the preliminary sampling rates. Sampling rates were calculated by averaging all the individual
sampling rates that were between the two horizontal lines. Sampling rates, RSDs of individual runs, and RSDs of
average sampling rates are shown in Table 4.7.2.1. Data shown in Table 4.7.2.1 are for the front section of the 3M
samplers. A five-hour experiment was performed for the 3M sampler because its capacity for MEK was exceeded before
six hours. The recommended sampling time is four hours.
Table 4.7.2.1 Determination of Sampling Rate and Recommneded Sampling Time |
|
|
SKC 575-002 Passive Sampler
|
|
3M 3520 OVM
|
|
MEK |
MIBK |
|
MEK |
MIBK |
time(h) |
(mL/min) |
RSD |
(mL/min) |
RSD(%) |
|
(mL/min) |
RSD |
(mL/min) |
RSD(%) |
|
0.083 0.167 0.50 1.00 2.00 3.00 4.00 5.00 6.00 8.00 10.00 |
16.12 16.87 16.55 17.38 17.53 17.21 16.87 16.88 16.94 16.49 |
6.4 3.2 0.5 1.8 0.6 0.9 3.8 0.5 1.8 1.5 |
14.32 13.58 13.84 13.47 13.59 13.60 13.52 13.29 13.62 13.40 |
3.2 1.7 2.8 1.3 0.7 0.8 3.8 0.5 3.4 1.5 |
|
33.28 33.80 33.52 33.64 31.21 32.22 31.36 31.71 27.24 22.47 17.83 |
0.3 3.9 1.6 3.3 1.5 4.4 0.8 3.8 5.0 3.5 2.2 |
27.29 27.39 26.64 26.95 25.74 26.88 26.49 27.50 26.64 28.04 27.41 |
3.9 3.6 0.7 1.4 0.9 4.3 3.8 3.8 3.4 1.6 2.2 |
|
mean | 16.88 | | 13.62 | | | 32.59 | | 27.00 | |
RSD(%) | 2.5 | | 2.1 | | | 3.3 | | 2.3 | |
|
Figure 4.7.2.1 Sampler capcity Data for MEK collected on SKC 575-002 Passive Sampler. |
|
Figure 4.7.2.2 Sampler capcity Data for MIBK collected on SKC 575-002 Passive Sampler. |
|
Figure 4.7.2.3 Sampler capcity Data for MEK collected on 3M 3520 OVM. |
|
Figure 4.7.2.4 Sampler capcity Data for MIBK collected on 3M 3520 OVM. |
Sampling rate is normally calculated using only the front section of two-section samplers. The 3M 3520 OVM is a
two-section sampler. When MEK collected on the back section was included in the total amount, the
resultant MEK sampling rates were comparable with those obtained above. This data should not be used to justify
sampling times longer than four hours, but it does show the value of a two-section sampler.
Table 4.7.2.2 MEK Sampling Rates for 3M 3520 OVM With Back Section Included |
|
time (h) |
mL/min |
RSD (%) |
|
6 8 10 |
31.54 32.84 32.29 |
4.0 0.7 1.5 |
|
4.8 Extraction efficiency and stability of extracted samples
A summary of extraction efficiencies (at concentrations near the RQL to 2 times the target concentration) for all
the sampling media used in this work is shown in Table 4.8. The extraction efficiency is dependent on the extraction
solvent as well as the internal standard. Other extraction solvents or internal standards may be used provided they
are tested as described below.
Table 4.8 Extraction Efficiency Summary |
|
medium |
MEK (%) |
MIBK (%) |
|
Anasorb CMS Anasorb 747 SKC 575-002 3M 3520 OVM |
100.3 97.9 92.2 98.0 |
102.3 99.0 92.9 96.5 |
|
4.8.1 SKC Anasorb CMS sampling tubes
Extraction efficiency
The extraction efficiencies of MEK and MIBK were determined by liquid-spiking 150 mg portions of Anasorb CMS with
the analytes at concentrations from the RQL to 2 times the target concentration. These samplers were stored overnight
at ambient temperature and then analyzed. The mean extraction efficiency over the working range of the RQL to 2 times
the target concentration is 100.3% for MEK and 102.3% for MIBK. The extraction efficiency for MEK from wet samplers
was lower than for dry samplers. These results were expected because of the instability of MEK on wet
carbon-based sorbents. The extraction efficiency for the wet samplers was not included in the overall
mean because it would bias the results. Wet sampling media used in extraction efficiency tests were all prepared by
sampling contaminant-free, humid air (about 80% relative humidity at 22°C) for four
hours at the recommended sampling rate.
Table 4.8.1.1 Extraction Efficiency of MEK from Anasorb CMS (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
0.808 1781 3562 7125 10450 14250
7125 |
100.7 98.4 99.7 104.0 101.8 101.3
89.9 |
101.6 98.1 101.0 96.9 101.1 100.6
86.3 |
92.8 98.4 98.2 104.7 101.8 99.5
87.1 |
98.7 98.7 100.6 104.4 99.6 103.5
91.5 |
98.5 98.4 99.9 102.5 101.1 101.2
88.7 |
|
Table 4.8.1.2 Extraction Efficiency of MIBK from Anasorb CMS (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
0.423 1219 2438 4876 7152 9753
4876 |
111.0 98.6 98.0 103.7 101.4 100.8
98.6 |
111.9 98.7 99.8 98.0 102.3 100.4
95.4 |
114.5 98.7 97.8 104.1 101.8 99.6
96.2 |
109.3 98.4 99.1 103.6 100.4 102.7
99.5 |
111.7 98.6 98.7 102.4 101.5 100.9
97.4 |
|
Stability of extracted samples
The stability of extracted samples was investigated by reanalyzing the target concentration samples a day after
the initial analysis. After the original analysis was performed two vials were recapped with new septa while the
remaining two retained their punctured septa. The samples were reanalyzed with fresh standards. Each septum was
punctured 6 times for each injection.
Table 4.8.1.3 Stability of Samples for MEK Extracted From Anasorb CMS |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
104.0 96.9
100.5 |
100.3 100.2 mean 100.3 |
-3.7 3.3
-0.2 |
|
104.7 104.4
104.6 |
89.3 84.9 mean 87.1 |
-15.4 -19.5
-17.5 |
|
Table 4.8.1.4 Stability of Samples for MIBK Extracted From Anasorb CMS |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
103.7 98.0
100.9 |
100.8 100.2 mean 100.5 |
-2.9 2.2
-0.4 |
|
104.1 103.6
103.9 |
96.8 96.8 mean 96.8 |
-7.3 -6.8
-7.1 |
|
The stability test for MEK was repeated with the reanalysis performed 12 hours after the initial analysis.
After the original analysis was performed, two vials were recapped with new septa while the remaining two retained
their punctured septa. The samples were reanalyzed with fresh standards. Each septum was punctured 6 times for
each injection.
Table 4.8.1.5 Stability of Samples for MEK Extracted From Anasorb CMS |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after 12 h (%) |
difference (%) |
|
initial (%) |
after 12 h (%) |
difference (%) |
|
98.3 97.5
97.9 |
96.6 96.1 mean 96.4 |
-1.7 -1.4
-1.6 |
|
99.1 99.0
99.1 |
92.6 94.0 mean 93.3 |
-6.5 -5.0
-5.8 |
|
4.8.2 SKC Anasorb 747 sampling tubes
Extraction efficiency
The extraction efficiencies of MEK and MIBK were determined by liquid-spiking 400 mg portions of Anasorb 747 with
the analytes at concentrations from the RQL to 2 times the target concentration. These samplers were stored overnight
at ambient temperature and then analyzed. The mean extraction efficiency over the working range of the RQL to 2 times
the target concentration is 97.9% for MEK and 99.0% for MIBK. The extraction efficiency for MEK from wet samplers was
lower than for dry samplers. These results were expected because of the instability of MEK on wet sorbents. The
extraction efficiency for the wet samplers was not included in the overall mean because it would bias the results.
Table 4.8.2.1 Extraction Efficiency of MEK from Anasorb 747 (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
0.950 1781 3562 7125 10450 14250
7125 |
86.5 94.4 94.8 98.8 101.9 92.7
87.3 |
114.5 94.9 97.1 98.8 99.7 98.7
86.4 |
104.1 94.5 94.7 99.4 99.1 99.0
86.0 |
100.7 94.8 95.4 96.7 99.5 98.2
91.7 |
101.5 94.7 95.5 98.4 100.1 97.2
87.9 |
|
Table 4.8.2.2 Extraction Efficiency of MIBK from Anasorb 747 (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
0.683 1219 2438 4876 7152 9753
4876 |
103.6 97.3 96.9 100.2 102.9 96.0
96.3 |
91.1 96.6 99.6 101.1 101.3 100.7
95.0 |
100.2 96.6 96.8 101.7 101.0 100.7
94.9 |
97.8 96.6 97.4 99.5 101.3 100.2
99.6 |
98.2 96.8 97.7 100.6 101.6 99.4
96.5 |
|
Stability of extracted samples
The stability of extracted samples was investigated by reanalyzing the target concentration samples a day after
initial analysis. After the original analysis was performed, two vials were recapped with new septa while the
remaining two retained their punctured septa. Each septum was punctured 6 times for each injection.
Table 4.8.2.3 Stability of Samples for MEK Extracted From Anasorb 747 |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
98.8 98.8
98.8 |
97.8 100.2 mean 99.0 |
-1.0 1.4
0.2 |
|
99.4 96.7
98.1 |
88.6 84.4 mean 86.5 |
-10.8 -12.3
-11.6 |
|
Table 4.8.2.4 Stability of Samples for MIBK Extracted From Anasorb 747 |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
100.2 101.1
100.7 |
100.5 102.1 mean 101.3 |
0.3 1.0
0.7 |
|
101.7 99.5
100.6 |
98.0 96.0 mean 97.0 |
-3.7 -3.5
-3.6 |
|
The stability test for MEK was repeated with the reanalysis performed 12 hours after the initial analysis. After
the original analysis was performed, two vials were recapped with new septa while the remaining two retained their
punctured septa. The samples were reanalyzed with fresh standards. Each septum was punctured 6 times for each
injection.
Table 4.8.2.5 Stability of Samples for MEK Extracted From Anasorb 747 |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after 12 h (%) |
difference (%) |
|
initial (%) |
after 12 h (%) |
difference (%) |
|
98.5 97.4
98.0 |
99.0 97.4 mean 98.2 |
0.5 0.0
0.3 |
|
98.9 98.1
98.5 |
96.0 93.3 mean 94.7 |
-2.9 -4.8
-3.9 |
|
4.8.3 SKC 575-002 Passive Samplers
Extraction efficiency
The extraction efficiencies of MEK and MIBK were determined by liquid spiking SKC 575-002 Passive
Samplers with the analytes at concentrations from the RQL to 2 times the target concentration. These samplers were
stored overnight at ambient temperature and then analyzed. The mean extraction efficiency over the working range
of the RQL to 2 times the target concentration is 92.2% for MEK and 92.9% for MIBK. The extraction efficiency for
MEK from wet samplers was lower than for dry samplers. These results were expected because of the instability of
MEK on wet sorbents. The extraction efficiency for the wet samplers was not included in the overall mean because
it would bias the results.
Table 4.8.3.1 Extraction Efficiency of MEK from SKC 575-002 Passive Samplers (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
1.282 594 1188 2375 3800 4750
2375 |
80.8 92.7 87.4 94.4 89.9 95.1
89.8
|
101.8 97.2 87.6 92.4 94.1 93.4
85.7
|
85.5 91.8 90.9 99.4 90.2 91.5
83.7
|
93.3 95.1 89.3 94.7 95.2 88.5
87.9
|
90.4 94.2 88.8 95.2 92.4 92.1
86.8 |
|
Table 4.8.3.2 Extraction Efficiency of MIBK from SKC 575-002 Passive Samplers (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
1.268 325 650 1300 1950 2601
1300 |
71.6 91.0 94.8 98.2 98.1 98.2
97.0 |
74.7 92.9 96.6 97.2 97.6 92.1
96.6 |
94.3 90.0 92.8 99.4 97.0 95.3
97.7 |
83.3 90.9 94.9 96.0 95.5 97.5
99.5 |
81.0 91.2 94.8 97.7 97.1 95.8
97.7 |
|
Stability of extracted samples
The stability of extracted samples was investigated by reanalyzing the target concentration samples a day after
initial analysis. After the original analysis was performed, two vials were recapped with new septa while the
remaining two retained their punctured septa. The samples were reanalyzed with fresh standards. Each septum was
punctured 6 times for each injection.
Table 4.8.3.3 Stability of Samples for MEK Extracted From SKC 575-002 Passive Samplers |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
94.4 92.4
93.4 |
93.0 92.7 mean 92.9 |
-1.4 0.3
-0.6 |
|
99.4 94.7
97.1 |
77.2 83.6 mean 80.4 |
-22.2 -11.1
-16.7 |
|
Table 4.8.3.4 Stability of Samples for MIBK Extracted From SKC 575-002 Passive Samplers |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
98.2 97.2
97.7 |
95.3 97.0 mean 96.2 |
-2.9 -0.2
-1.6 |
|
99.4 96.0
97.7 |
92.8 87.8 mean 90.3 |
-6.6 -8.2
-7.4 |
|
The stability test for MEK was repeated with the reanalysis performed 12 hours after the initial analysis.
After the original analysis was performed, two vials were recapped with new septa while the remaining two retained
their punctured septa. The samples were reanalyzed with fresh standards. Each septum was punctured 6 times for each
injection.
Table 4.8.3.5 Stability of Samples for MEK Extracted From SKC 575-002 Passive Samplers |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after 12 h (%) |
difference (%) |
|
initial (%) |
after 12 h (%) |
difference (%) |
|
89.7 90.3
90.0 |
94.6 93.2 mean 93.9 |
4.9 2.9
3.9 |
|
89.7 94.5
92.1 |
89.6 86.4 mean 88.0 |
-0.1 -8.1
-4.1 |
|
4.8.4 3M 3520 OVM
Extraction efficiency
The extraction efficiencies of MEK and MIBK were determined by liquid-spiking 3M 3520 OVM charcoal wafers with the
analytes at concentrations from the RQL to 2 times the target concentration. These samples were stored overnight at
ambient temperature and then analyzed. The mean extraction efficiency over the working range of the RQL to 2 times
the target concentration is 98.0% for MEK and 96.5% for MIBK. The extraction efficiency for MEK from wet samplers was
lower than for dry samplers. These results were expected because of the instability of MEK on wet sorbents. The
extraction efficiency for the wet samplers was not included in the overall mean because it would bias the results.
Table 4.8.4.1 Extraction Efficiency of MEK from 3M 3520 OVM Charcoal Wafers (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
0.760 1188 2375 4750 7125 9500
4750 |
108.6 100.1 97.9 96.4 97.1 89.4
88.2 |
91.7 93.2 102.1 96.8 95.6 98.8
89.3 |
107.2 92.4 103.8 94.0 100.9 95.7
90.1 |
113.7 94.7 98.3 95.0 93.9 94.3
91.4 |
105.3 95.1 100.5 95.6 96.9 94.6
89.8 |
|
Table 4.8.4.2 Extraction Efficiency of MIBK from 3M 3520 OVM Charcoal Wafers (%) |
|
level
|
sample number
|
|
× target concn |
µg per sample |
1 |
2 |
3 |
4 |
mean |
|
RQL 0.25 0.5 1.0 1.5 2.0
1.0 (wet) |
0.943 650 1300 2601 3901 5201
2601 |
92.0 98.2 97.2 99.7 98.5 100.7
98.7 |
87.3 96.1 98.7 98.2 101.3 97.2
97.5 |
84.8 93.2 98.4 96.8 98.3 103.0
93.8 |
81.5 97.1 98.9 96.2 100.2 101.3
98.1 |
86.4 96.2 98.3 97.7 99.6 100.6
97.0 |
|
Stability of extracted samples
The stability of extracted samples was investigated by reanalyzing the target concentration samples a day after
initial analysis. After the original analysis was performed, two vials were recapped with new septa while the
remaining two retained their punctured septa. The samples were reanalyzed with fresh standards. Each septum was
punctured 6 times for each injection.
Table 4.8.4.3 Stability of Samples for MEK Extracted From 3M 3520 OVM Charcoal Wafers |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
96.4 96.8
96.6 |
97.2 94.3 mean 95.8 |
0.8 -2.5
-0.9 |
|
94.0 95.0
94.5 |
84.2 77.9 mean 81.1 |
-9.8 -17.1
-13.5 |
|
Table 4.8.4.4 Stability of Samples for MIBK Extracted From 3M 3520 OVM Charcoal Wafers |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after one day (%) |
difference (%) |
|
initial (%) |
after one day (%) |
difference (%) |
|
99.7 98.2
99.0 |
99.4 100.1 mean 99.8 |
-0.3 1.9
0.8 |
|
96.8 96.2
96.5 |
93.8 96.1 mean 95.0 |
-3.0 -0.1
-1.6 |
|
The stability test for MEK was repeated with the reanalysis performed 12 hours after the initial analysis. After
the original analysis was performed, two vials were recapped with new septa while the remaining two retained their
punctured septa. The samples were reanalyzed with fresh standards. Each septum was punctured 6 times for each
injection.
Table 4.8.4.5 Stability of Samples for MEK Extracted From 3M 3520 OVM Charcoal Wafers |
|
punctured septa replaced
|
|
punctured septa retained
|
initial (%) |
after 12 h (%) |
difference (%) |
|
initial (%) |
after 12 h (%) |
difference (%) |
|
100.0 103.5
101.8 |
95.3 94.9 mean 95.1 |
-4.7 -8.6
-6.7 |
|
102.7 103.6
103.2 |
94.1 94.4 mean 94.3 |
-8.6 -9.2
-8.9 |
|
4.9 Interferences (sampling)
4.9.1 SKC Anasorb CMS sampling tubes
Retention
The ability of SKC Anasorb CMS sampling tubes to retain MEK and MIBK after collection was tested by sampling an
atmosphere containing 1178 mg/m3 MEK and 806 mg/m3 MIBK at an absolute humidity of 14.6
milligrams of water per liter of air (77.8% relative humidity at 21.4°C). Six samplers had contaminated air
drawn through them at about 50 mL/min for 60 min. Sampling was discontinued and three samples set aside. The
generation system was flushed with contaminant-free air. Sampling was resumed with the other three samples with
contaminant-free humid air drawn through them at 50 mL/min for 3 h and then all six samplers were
analyzed. Recoveries for the two sets are expressed as percent of theoretical.
Table 4.9.1 Retention (%) of MEK and MIBK on Anasorb CMS |
|
|
1 |
2 |
3 |
mean |
set |
MEK |
MIBK |
MEK |
MIBK |
MEK |
MIBK |
MEK |
MIBK |
|
first second second/first |
96.7 92.2
|
96.1 93.4
|
96.2 93.1
|
94.7 93.4
|
97.2 91.9
|
96.5 92.5
|
96.7 92.4 95.6 |
95.8 93.1 97.2 |
|
Low humidity
The ability of SKC Anasorb CMS sampling tubes to collect MEK and MIBK from a relatively dry atmosphere was tested
by sampling an atmosphere containing 1203 mg/m3 of MEK and 823 mg/m3 of MIBK at an absolute
humidity of 2.7 milligrams of water per liter of air (13.2% relative humidity at 22.6°C). Three samplers had
contaminated air drawn through them at 50 mL/min for 240 min. All three samples were immediately analyzed. The
sample results were 96.3%, 97.2% and 95.1% of theoretical for MEK; and 98.6%, 99.3%,
and 98.2% of theoretical for MIBK.
Low concentration
The ability of SKC Anasorb CMS sampling tubes to collect MEK and MIBK at low concentrations was tested by sampling
an atmosphere containing 60.4 mg/m3 of MEK and 41.3 mg/m3 of MIBK at an absolute humidity of
15.5 milligrams of water per liter of air (79.7% relative humidity at 22.3°C). Three samplers had contaminated
air drawn through them at 50 mL/min for 240 min. All three samples were immediately analyzed. The sample results
were 94.9%, 98.2% and 97.2% of theoretical for MEK and 101.1%, 104.7% and 104.4% of theoretical for MIBK.
Sampling interferences
The ability of SKC Anasorb CMS sampling tubes to collect MEK and MIBK was tested in the presence of potential
interferences by sampling an atmosphere containing 578 mg/m3 of MEK and 395 mg/m3 of MIBK at
an absolute humidity of 15.6 milligrams of water per liter of air (79.0% relative humidity at 22.23°C) and
553.3 mg/m3 acetone, 253.7 mg/m3 isopropyl alcohol, 190.1 mg/m3 toluene, 92.5
mg/m3 xylene isomers, and 16.3 mg/m3 ethyl benzene. Three samplers had contaminated air
drawn through them at 50 mL/min for 240 min. All three samples were immediately analyzed. The sample results
were 99.1%, 99.3% and 99.0% of theoretical for MEK; and 102.2%, 103.0% and 102.4% of theoretical for MIBK.
4.9.2 SKC 575-002 Passive Samplers and 3M 3520 OVMs
Reverse diffusion
The ability of SKC 575-002 Passive Samplers and of 3M 3520 OVMs to retain MEK and MIBK after collection was
tested by sampling an atmosphere containing 1178 mg/m3 MEK and 806 mg/m3 MIBK at an
absolute humidity of 14.6 milligrams of water per liter of air (77.8% relative humidity at 21.4°C).
Six of each sampler were exposed to contaminated air for one hour. Sampling was discontinued and three of each
sampler were set aside (1st set). The generation system was flushed with contaminant-free
air. Sampling was resumed with the remaining six samplers exposed to contaminant-free humid air for an additional
three hours (2nd set). Results are presented in terms of micrograms of analyte found on the sampler.
The means of the second set were 99.3% for MEK and 100.0% for MIBK of the means of the first set for SKC
575-002 Passive Samplers. The means of the second set were 96.0% for MEK and 98.6% for MIBK of the
means of the first set for 3M 3520 OVMs.
Table 4.9.2.1 Reverse Diffusion For SKC 575-002 Passive Sampler (µg) |
|
set |
1 |
2 |
3 |
|
|
MEK |
MIBK |
MEK |
MIBK |
MEK |
MIBK |
first second |
1357.45 1355.55 |
741.52 739.86 |
1368.54 1360.50 |
732.50 737.37 |
1405.26 1387.31 |
753.41 750.30 |
means
|
first second
|
1377.08 1367.79 |
742.48 742.51 |
|
Table 4.9.2.2 Reverse Diffusion For 3M OVM (µg) |
|
set |
1 |
2 |
3 |
|
|
MEK |
MIBK |
MEK |
MIBK |
MEK |
MIBK |
first second
|
2700.73 2580.20 |
1520.43 1471.29 |
2627.96 2607.50 |
1464.63 1510.12 |
2811.44 2628.50 |
1535.59 1477.16 |
means
|
first second
|
2713.38 2605.40 |
1506.88 1486.19 |
|
Low humidity
Three SKC and three 3M diffusive samplers were used to sample a test atmosphere containing 1203 mg/m3
MEK and 823 mg/m3 MIBK. The absolute humidity of the test atmosphere was 2.7 milligrams of water per
liter of air (13.2% relative humidity at 22.6°C). The recoveries (% theoretical) are shown in Table 4.9.2.3.
Table 4.9.2.3 Low Humidity (Recovery, % of Theoretical) |
|
sampler |
1 |
|
2 |
|
3 |
|
MEK |
MIBK |
|
MEK |
MIBK |
|
MEK |
MIBK |
|
SKC 575-002 3M 3520 |
|
92.2 95.5 |
102.5 109.2 |
|
94.9 93.9 |
104.9 102.6 |
|
92.8 92.9 |
103.1 101.0 |
|
Low concentration
Three SKC and three 3M diffusive samplers were used to sample a test atmosphere containing 60.3 mg/m3
MEK and 41.3 mg/m3 MIBK. The absolute humidity of the test atmosphere was 15.5 milligrams of water per
liter of air (79.7% relative humidity at 22.3°C). The recoveries (% theoretical) are shown in Table 4.9.2.4.
Table 4.9.2.4 Low Concentration (Recovery, % of Theoretical) |
|
sampler |
1 |
|
2 |
|
3 |
|
MEK |
MIBK |
|
MEK |
MIBK |
|
MEK |
MIBK |
|
SKC 575-002 3M 3520 |
|
92.2 89.8 |
101.6 95.0 |
|
95.6 93.4 |
105.2 97.9 |
|
90.3 92.2 |
96.8 98.5 |
|
Sampling interferences
Three SKC and three 3M diffusive samplers were used to sample a test atmosphere containing 578 mg/m3
of MEK and 395 mg/m3 of MIBK; and 553.3 mg/m3 of acetone, 253.7 mg/m3 of isopropyl
alcohol, 190.1 mg/m3 of toluene, 92.5 mg/m3 of xylene isomers, and 16.3 mg/m3 of
ethyl benzene. The absolute humidity was 15.6 milligrams of water per liter of air (79.0% relative humidity at
22.3°C). The recoveries (% theoretical) are shown in Table 4.9.2.5.
Table 4.9.2.5 Sampling Interference (Recovery, % of Theoretical) |
|
sampler |
1 |
|
2 |
|
3 |
|
MEK |
MIBK |
|
MEK |
MIBK |
|
MEK |
MIBK |
|
SKC 575-002 3M 3520 |
|
103.2 95.0 |
108.5 103.1 |
|
97.6 93.6 |
102.2 101.8 |
|
101.6 93.5 |
107.3 102.8 |
|
4.10 Qualitative analysis
The identity of suspected MEK or MIBK GC peaks can be confirmed by GC/Mass Spectrometry. Mass spectra for the
analytes are shown below.
Figure 4.10.1 Mass spectrum of MEK. |
|
Figure 4.10.2 Mass spectrum of MIBK |
References
1. OSHA Salt Lake Technical Center, Chemical Sampling Information,
http://www.osha.gov/dts/chemicalsampling/data/CH_222300.html
(accessed Feb 2000).
(Back to text)
2. OSHA Salt Lake Technical Center, Chemical Sampling Information,
http://www.osha.gov/dts/chemicalsampling/data/CH_245600.html
(accessed Feb 2000).
(Back to text)
3. Documentation of the Threshold Limit Values and Biological Exposure Indices,
6th ed., American Conference of Governmental Industrial Hygienists, Inc.: Cincinnati, OH,
1991, vol. II, pp.1002-1004 and 1019-1021.
(Back to text)
4. Supplements (1996) to the 6th Edition of: Documentation of the Threshold Limit
Values and Biological Exposure Indices, 6th ed., American Conference of Governmental Industrial
Hygienists, Inc.: Cincinnati, OH, 1991, vol. II, pp. Supplement: Methyl Isobutyl Ketone
(MIBK)- BEI 1-3.
(Back to text)
5. Documentation of the Threshold Limit Values and Biological Exposure Indices,
6th ed., American Conference of Governmental Industrial Hygienists, Inc.: Cincinnati, OH, 1991,
vol. II, pp.1002-1004 and 1019-1021.
(Back to text)
6. Documentation of the Threshold Limit Values and Biological Exposure Indices,
6th ed., American Conference of Governmental Industrial Hygienists, Inc.: Cincinnati, OH, 1991,
vol. II, pp.1002-1004 and 1019-1021.
(Back to text)
7. OSHA Salt Lake Technical Center, Chemical Sampling Information,
http://www.osha.gov/dts/chemicalsampling/toc/toc_chemsamp.html
(Accessed Jan 2000).
(Back to text)
8.Burright, D.; Chan, Y.; Eide, M.; Elskamp, C.; Hendricks, W.; Rose, M. C.
Evaluation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis;
OSHA Salt Lake Technical Center, U.S. Department of Labor: Salt Lake City, UT, 1999.
(Back to text)
9.Burright, D.; Chan, Y.; Eide, M.; Elskamp, C.; Hendricks, W.; Rose, M. C.
Evaluation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis;
OSHA Salt Lake Technical Center, U.S. Department of Labor: Salt Lake City, UT, 1999.
(Back to text)
10. Occupational Exposure to Hazardous Chemicals in Laboratories.
Code of Federal Regulations, Part 1910.1450, Title 29, 1998.
(Back to text)
11. Burright, D.; Chan, Y.; Eide, M.; Elskamp, C.; Hendricks, W.; Rose, M. C.
Evaluation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis;
OSHA Salt Lake Technical Center, U.S. Department of Labor: Salt Lake City, UT, 1999.
(Back to text)
12. Burright, D.; Chan, Y.; Eide, M.; Elskamp, C.; Hendricks, W.; Rose, M. C.
Evaluation Guidelines for Air Sampling Methods Utilizing Chromatographic Analysis;
OSHA Salt Lake Technical Center, U.S. Department of Labor: Salt Lake City, UT, 1999.
(Back to text)
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