![spacer image spacer image](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/SLTC/gif/new/methodspacer.gif) |
4-NITRODIPHENYL
|
|
Method no.: |
PV2082 |
|
Control no.: |
T-PV2082-01-9409-CH |
|
Matrix: |
Air |
|
Target concentration: |
10 ppb (81.5 µg/m³)(OSHA Regulation 1910.1003, lowest feasible
limit)
|
|
Procedure: |
Samples are collected by drawing a known volume of air
through an OSHA versatile sampler (OVS-2) tubes, containing a glass fiber
filter and two sections of XAD-2 adsorbent.
Samples are desorbed with ethyl acetate and analyzed by liquid
chromatography (LC) using an ultra-violet detector (UV). |
|
Recommended air volume and sampling rate:
|
240 L at 1.0 L/min |
|
Reliable quantitation limit: |
0.018 ppb (0.15 µg/m3) |
|
Special requirements: |
Samples should be stored in a refrigerator when not in
transit. |
|
Status of method: |
Partially Evaluated Method. This method has been subjected
to established evaluation procedures, and is presented for information and
trial use. |
|
Date: September 1994
Chemist: Wayne Potter |
Organic Service Branch I
OSHA Salt Lake Technical Center
Salt Lake City, UT 84115-1802
- General Discussion
1.1 Background
1.1.1 History
Airborne 4-nitrodiphenyl has been determined by collection on a glass
fiber filter and silica gel tube connected in series and analyzed by gas
chromatograph with a flame ionization detector in
NIOSH proposed method P & CAM 273. One of the potential disadvantages
of this method is connecting the glass fiber filter and silica gel tube is
series. Another disadvantage is that flame
ionization detection is not very sensitive to 4-nitrodiphenyl.
In this method, airborne 4-nitrodiphenyl is collected on one OVS-2
sampler and analyzed on a liquid chromatograph with an ultra-violet (UV)
detector. This detector is very sensitive to 4-nitrodiphenyl which allows a
much lower detection limit. 4-Nitrodiphenyl under 29 CFR 1910.1003 is
considered a potential human carcinogen. A target concentration of 10 ppb
was picked as
the lowest feasible amount to work with.
1.1.2 Toxic effects (This section is for information only and should not
be taken as the basis of OSHA policy.) (Ref. 5.1, 5.2, and 5.3)
The International Agency for Research on Cancer Working Group on the
Evaluation of the Carcinogenic Risk of Chemicals to Man found no reports on
carcinogenicity of 4-Nitrodiphenyl to
man. However, the group concluded that it is not possible to separate the
exposures to 4-nitrodiphenyl from exposures to 4-aminobiphenyl because the
former is converted to the latter by
reduction. 4-Aminobiphenyl is a recognized human bladder carcinogen (Ref.
5.1).
4-Nitrodiphenyl is a confirmed carcinogen with experimental carcinogenic,
neoplastigenic and tumorigenic data. It is a poison by intraperitoneal
route and moderately toxic by ingestion. When
heated to decomposition it emits toxic fumes of NOx. (Ref. 5.2).
Exposure to 4-nitrodiphenyl can cause headaches, lethargy, dizziness,
dyspnea, ataxia, weakness, methemoglobinemia; urinary burning and acute
hemorrhagic cystitis. (Ref. 5.3).
1.1.3 Workplace exposure (Ref. 5.4)
4-Nitrodiphenyl is used as a dye intermediate, fungicide, plasticizer for
cellulosics and a wood preservative. No data is available on the extent of
work place exposure.
1.1.4 Physical properties and other descriptive information (Ref. 5.1
unless otherwise indicated).
Synonyms: |
Nitrodiphenyl, 4-nitrobiphenyl, p-phenyl-nitrobenzene,
4-phenyl-nitrobenzene (Ref. 5.5) |
CAS number: |
92-93-3 |
IMIS: |
1875 |
RTECS: |
DV5600000; 20760 (Ref. 5.5) |
Molecular weight: |
199.22 |
Boiling point: |
340°C @ 101.3 kPa (760 mmHg) |
Melting point: |
114°C |
Odor: |
Sweetish odor |
Color: |
Yellow to white needles |
Solubility: |
Insoluble in water, slightly soluble in cold alcohol, very
soluble in ether. |
Molecular formula: |
C12H9NO2 |
Structural formula: |
![structural formula for
4-Nitrodiphenyl structural formula for 4-Nitrodiphenyl](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/waynit.gif) |
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 overall procedure (DLOP)
The detection limit of the overall procedure is 0.011 g per sample (0.006
ppb or 0.046 µg/m³). This is the amount of analyte spiked on the sampler
that will give a response that is significantly
different from the background response of a sampler blank.
The DLOP is defined as the concentration of analyte that gives a response
(YDLOP) that is significantly different (three standard
deviations (SDBR)) from the background response
(YBR).
YDLOP - YBR = 3(SDBR)
The direct measurement of YBR and SDBR in
chromatographic methods is typically inconvenient, and difficult because
YBR is usually extremely low. Estimates of these parameters can
be made
with data obtained from the analysis of a series of samples whose responses
are in the vicinity of the background response. The regression curve
obtained for a plot of instrument response
versus concentration of analyte will usually be linear. Assuming
SDBR and the precision of data about the curve are similar, the
standard error of estimate (SEE) for the regression curve can be
substituted for SDBR in the above equation. The following
calculations derive a formula for the DLOP:
![equation for SEE equation
for SEE](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/image13.gif)
Yobs = |
observed response |
Yest = |
estimated response
from regression
curve |
n = |
total no. of data points |
k = |
2 for a linear regression curve |
At point YDLOP on the regression curve
A = analytical sensitivity (slope)
therefore
![equation 1 for DLOP equation 1 for DLOP](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/image15.gif)
Substituting 3(SEE) + YBR for YDLOP gives
The DLOP is measured as mass per sample and expressed as equivalent air
concentrations, based on the recommended sampling parameters. Ten samplers
were spiked with equal descending
increments of analyte, such that the highest sampler loading was 0.2 µg/sample. This is the amount, when spiked on a sampler, that would produce
a peak approximately 10 times the
background response for the sample blank. These spiked samplers, and the
sample blank were analyzed with the recommended analytical parameters, and
the data obtained used to calculate
the required parameters (A and SEE) for the calculation of the DLOP. Values
of 52245.1 and 187.194 were obtained for A and SEE respectively. DLOP was
calculated to be 0.011 µg/sample
(0.006 ppb or 0.046 µg/m3).
Table 1.2.1
Detection Limit of the Overall Procedure
|
mass per sample
(µg) |
area counts
(µV-s) |
|
0
.02
.04
.06
.08
.10
.12
.14
.16
.18
.20 |
0
1.570
2.642
4.090
4.971
6.065
6.953
8.325
8.988
9.915
11.132 |
|
![Figure
1.2.1 Plot of data to determine the DLOP/RQL Figure 1.2.1 Plot of data to determine the DLOP/RQL](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/t-pv201.gif)
Mass (µg) per sample
Figure 1.2.1 Plot of data to determine the DLOP/RQL
1.2.2 Reliable quantitation limit (RQL)
The reliable quantitation limit is 0.036 µg
per sample (0.018 ppb or 0.15 µg/m3).
This is the amount of analyte spiked on a sampler that will give a
signal that is considered the lower limit for precise quantitative
measurements.
The RQL is considered the lower limit for precise
quantitative
measurements. It is determined from the regression line data
obtained
for the calculation of the DLOP (Section 1.2.1), providing at
least
75% of the analyte is recovered. The RQL is defined as the
concentration of analyte that gives a response (YRQL)
such
that
YRQL - YBR = 10(SDBR)
therefore
![Figure 1.2.3 Chromatogram of the RQL Figure 1.2.3 Chromatogram of the RQL](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/t-pv202.gif)
Figure 1.2.3 Chromatogram of the RQL
- Sampling Procedure
2.1 Apparatus
2.1.1 Samples are collected using a personal sampling pump
calibrated,
with the sampling device attached, to within ±5% of the recommended
flow
rate.
Samples are collected on OVS-2 tubes, which are specially made
11-mm
i.d. × 13-mm o.d. × 5.0 cm long glass tubes that taper to 6-mm o.d. ×
2.5 cm. Each tube is packed with a 140-mg back section and a 270-mg
front
section of XAD-2 and a 13-mm diameter glass fiber filter. The back
section
is retained by two foam plugs and the sampling section is between one
foam
plug and the glass fiber filter. The glass fiber filter is held next
to
the sampling section by a polytetrafluoroethylene (PTFE) retainer.
These
tubes are commercially available from SKC Inc. and Forest
Biomedical.
![Schematic
of the OVS-2 sample collecting tube Schematic of the OVS-2 sample collecting tube](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/t-pv203.gif)
Figure 2.1.1 Schematic of OVS-2 sample collecting tubes.
2.2 Technique
2.2.1 Immediately before sampling, remove the caps. All tubes
should be
from the same lot.
2.2.2 Attach small end of the sampling tube to the pump with
flexible
tubing. Position the tube so that sampled air passes through the front
section of the tube first.
2.2.3 Air being sampled should not pass through any hose or tubing
before entering the sampling tube.
2.2.4 Attach the sampler vertically with the open end pointing
downward, in the worker's breathing zone, and positioned so it does
not
impede work performance or safety.
2.2.5 After sampling for the appropriate time, remove the sample
and
seal the tube with plastic end caps. Wrap each sample end-to-end with
a
Form OSHA-21 seal.
2.2.6 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.
2.2.7 Record sample volumes (in liters of air) for each sample,
along
with any potential interferences.
2.2.8 Ship any bulk samples in separate containers from the air
samples.
2.2.9 Submit the samples to the laboratory for analysis as soon as
possible after sampling. If delay is unavoidable, store the samples in
a
refrigerator.
2.3 Desorption efficiency
The desorption efficiencies of 4-nitrodiphenyl were determined by
liquid-spiking the 13-mm glass fiber filters and also an amount of
XAD-2
adsorbent equal to the adsorbing section (270mg) of an OVS-2 tube with
the
analyte at 0.1 to 2 times the target concentration. The loadings on
the
tubes were 2.01, 10.05, 20.1, and 40.2 µg
of 4-nitrodiphenyl. These samples were stored overnight at ambient
temperature and then desorbed and analyzed by LC-UV. The average
desorption efficiency over the studied range was 99.3%.
Table 2.3.1
Desorption Efficiency of 4-Nitrodiphenyl
From GFF
|
Tube # |
% Recovered |
|
0.1 × |
0.5 × |
1.0 × |
2.0 × |
|
2.01 µg |
10.05 µg |
20.1 µg |
40.2 µg |
|
1
2
3
4
5
6
|
97.2
92.5
93.3
95.6
87.6
92.4
|
101.8
103.1
101.4
104.9
102.5
100.0
|
103.9
100.9
100.2
101.4
101.9
100.8
|
101.6
100.6
100.7
100.8
101.3
100.9
|
average |
93.1 |
102.3 |
101.5 |
101.0 |
overall average |
99.5 |
|
|
|
standard deviation |
±4.28 |
|
|
|
|
Table 2.3.2
Desorption Efficiency of 4-Nitrodiphenyl
From XAD-2
|
Tube # |
% Recovered |
|
0.1 × |
0.5 × |
1.0 × |
2.0 × |
|
2.01 µg |
10.05 µg |
20.1 µg |
40.2 µg |
|
1
2
3
4
5
6
|
100.3
94.8
97.1
101.2
97.1
96.8
|
102.0
102.2
94.0
94.6
95.5
98.7
|
100.1
100.1
97.6
100.0
101.4
100.2
|
100.4
100.4
100.9
100.1
100.6
99.4
|
average |
97.9 |
97.8 |
99.9 |
100.3 |
overall average |
99.0 |
|
|
|
standard deviation |
±1.31 |
|
|
|
|
2.4 Retention efficiency
The sampling tubes were spiked with 40.2 µg
(20 ppb or 160 µg/m³)
4-nitrodiphenyl, allowed to equilibrate overnight at room temperature,
and
then had 240 L humid air (80% RH at 25°C)
drawn through them at 1.0 Lpm. The sampling tubes were opened and the
GFF,
the front section and the back section were each put in separate
vials.
The samples were desorbed and analyzed by LC-UV. The retention
efficiency
averaged 98.8%. There was no 4-nitrodiphenyl found on the back
sections of
the tubes.
Table 2.4
Retention Efficiency of 4-Nitrodiphenyl
|
Tube # |
% Recovered |
|
GFF |
Front Section |
Back Section |
Total |
|
1
2
3
4
5
6
|
90.5
77.0
85.7
78.9
84.0
89.8
|
8.1
18.6
14.4
18.8
16.0
10.7
|
0
0
0
0
0
0
|
98.6
95.6
100.1
97.7
100.0
100.5
|
|
|
average |
|
98.8 |
|
2.5 Sample storage
The glass fiber filter of twelve sampling tubes were each spiked
with
20.1 µg (80 µg/m³)
of 4-nitrodiphenyl. They were sealed and stored at room temperature.
The
next day 240 L of humid air (80% RH at 25°C)
was drawn through each tube at 1.0 L/min. Half of the tubes were
stored
in a drawer at ambient temperature and the other half were stored in
a
refrigerator at 0°C. After 7 days
of storage three samples from the tubes stored under refrigeration
and
three samples from ambient storage were analyzed. The remaining
samples
were analyzed after 14 days of storage. The amounts recovered, which
are
not corrected for desorption efficiency, indicate that the samples
should be refrigerated.
Table 2.5
Storage Test for 4-Nitrodiphenyl
|
Ambient Storage |
Refrigerator Storage |
Time (days) |
% Recovered |
Time (days) |
% Recovered |
|
7
7
7
14
14
14
average
|
93.8
91.4
91.4
85.6
83.1
77.4
87.1
|
7
7
7
14
14
14
average
|
98.6
102.0
100.1
99.1
99.7
99.5
99.8
|
|
2.6 Recommended air volume and sampling rate.
Based on the data collected in this evaluation, 240 L air samples
should be collected at a sampling rate of 1.0 L/min.
2.7 Interferences (sampling)
2.7.1 It is not known if any compounds will severely interfere with
the
collection of 4-nitrodiphenyl on OVS-2 sampling tubes. In general, the
presence of other contaminant vapors in the air will reduce the
capacity
of the sampling tube to collect 4-nitrodiphenyl.
2.7.2 Suspected interferences should be reported to the laboratory
with
submitted samples.
2.8 Safety precautions (sampling)
2.8.1 Attach the sampling equipment to the worker in such a manner
that
it will not interfere with work performance or safety.
2.8.2 Follow all safety practices that apply to the work area being
sampled.
2.8.3 Wear eye protection at all times while in the work areas.
- Analytical Procedure
3.1 Apparatus
3.1.1 The instrument used in this study was a liquid chromatograph
equipped with an ultra-violet detector, specifically a Waters model
600E
system controller, a Waters 490E detector and a Waters 717
autosampler.
3.1.2 An LC column capable of separating the analyte from any
interferences. The column used in this study was a Supelco LC-8-DB, 5 µm
(4.6×250 mm).
3.1.3 An electronic integrator or some suitable method of measuring
peak areas.
3.1.4 Four milliliter vials with Teflon-lined caps.
3.1.5 A 10 µL syringe or other
convenient size for sample injection.
3.1.6 Pipets for dispensing the desorbing solution. A 2 mL
dispenser
was used in this study.
3.1.7 Volumetric flasks - 10 mL and other convenient sizes for
preparing standards.
3.2 Reagents
3.2.1 4-Nitrodiphenyl, Reagent grade.
3.2.2 Ethyl Acetate, HPLC grade.
3.2.3 Acetonitrile, HPLC grade.
3.2.4 Water, HPLC grade.
3.3 Standard preparation
3.3.1 At least two separate stock standards are prepared by
diluting a
known quantity of 4-nitrodiphenyl with the desorbing solution of ethyl
acetate. The concentration of these stock standards was 2010 µg/mL.
3.3.2 Dilutions of these stock standards were prepared to bracket
the
samples. The range of the standards used in this study was from 2.01
to
40.2 µg/mL.
3.4 Sample preparation
3.4.1 Sample tubes are opened and the front section (GFF and 270 mg
adsorbent), and back section of each tube are placed in separate 4 mL
vials.
3.4.2 Each section is desorbed with 2 mL of ethyl acetate.
3.4.3 The vials are sealed immediately and allowed to desorb for
one
hour on a mechanical shaker.
3.5 Analysis
3.5.1 Liquid chromatograph conditions.
Injection size: |
5 µL
(an injection size greater than 5 µL
will cause peak splitting). |
Column: |
Supelco LC-8 |
LC-8-DB: |
5 µm, 25cm × 4.6mm i.d. |
Mobile phase: |
55% Acetonitrile in water (v/v) |
Flow rate: |
1 mL/min |
UV detector: |
305 nm |
Retention time: |
6.0 min |
Chromatogram: |
|
![Figure 3.5.1 Chromatogram at the target concentration Figure 3.5.1 Chromatogram at the target concentration](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/t-pv204.gif)
Figure 3.5.1 Chromatogram at the target
concentration
3.5.2 Peak areas are measured by an integrator or other suitable
means.
3.6 Interferences (analytical)
3.6.1 Any compound that produces a response to UV at 305 nm, and
has a
similar retention time as the analyte is a potential interference. If
any
potential interferences were reported, they should be considered
before
samples are desorbed. Generally, chromatographic conditions can be
altered
to separate an interference from the analyte.
3.6.2 When necessary, the identity or purity of an analyte peak may
be
confirmed by a GC-mass spectrometer or by another analytical
procedure.
3.7 Calculations
3.7.1 The calibration curve was made from at least four standards
at
different concentrations bracketing the samples.
3.7.2 The values for the samples are obtained from the calibration
curve.
3.7.3 To calculate the concentration of analyte in the air sample
the
following formulas are used:
![equation for mass of analyte in
sample equation for
mass of analyte in sample](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/image24.gif)
![equation for the number of moles of
analyte equation for
the number of moles of analyte](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/image25.gif)
Volume the analyte will occupy at 25°C
and 760 mmHg is number of moles of analyte times the molar volume at 25°C
and 760 mmHg.
![initial equation for ppm initial
equation for ppm](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/image26.gif)
3.7.4 The above equations can be consolidated to the following
formula.
![final equation for ppm final equation
for ppm](https://webarchive.library.unt.edu/eot2008/20081106071757im_/http://www.osha.gov/dts/sltc/methods/partial/t-pv2082-01-9409-ch/image28.gif)
µg/mL = concentration of
analyte in sample or standard
24.46 = molar volume (liters/mole) at 25°C
and 760 mmHg
MW = molecular weight (g/mole)
DV = desorption volume
10 L = 10 liter air sample
DE = desorption efficiency
* All units must cancel.
3.7.5 This calculation is done for each section of the sampling
tube
and the results added together after a blank correction is performed,
if
necessary.
3.8 Safety precautions
3.8.1 Avoid skin contact and inhalation of all chemicals.
3.8.2 Wear safety glasses, gloves and a lab coat at all times while
in
the laboratory areas.
- Recommendations for Further Study
Collection studies should be performed.
- References
5.1 American Conference of Governmental Industrial Hygienists, Inc.
"Documentation of the Threshold Limit Values", 5th ed., 1986.
Cincinnati, Ohio, p.433.
5.2 Sax, N., "Dangerous Properties of Industrial
Materials",
8th edition, Van Nostrand Reinhold Co., New York, 1992, p. 2524.
5.3 Cameo Database, 1992, NOAA.
5.4 Lewis, R., "Hawley's Condensed Chemical Dictionary",
twelfth edition, Van Nostrand Reinhold Co., New York, 1993, p.826.
5.5 Sweet, D., "Registry of Toxic Effects of Chemical
Substances", 1986-86 Edition, U.S. Department of Health and Human
Services, Public Health Service, Center for Disease Control, NIOSH,
1987,
Vol. 2, p.1186.
|