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| Orientation and Training Food and Drug Administration |
| DOCUMENT NO.: IV-06 | VERSION NO.:1.2 | Section 6 - Elemental Analysis | EFFECTIVE DATE: 10/01/2003 | REVISED: 06/27/2008 |
6.2 Exercises for Entry Level Analysts
The exercises in this section are intended to expose the novice analyst to
some of the more frequently used methods for detecting lead and for quantifying
lead and cadmium. For more detailed information regarding methods on the determination
of these and additional elements, standards, sample preparation, digestions,
instrumentation, or data treatment consult the CFSAN web site and the Elemental
Analysis Manual (EAM).
View manual at http://www.cfsan.fda.gov/~dms/eam-toc.html
6.2.1 Qualitative Identification
of Lead in Ceramicware and Solder Alloys
A. Introduction
Because the scope of the ceramicware program is limited to leachable lead and
cadmium, and the use of lead is routine in ceramicware items, FDA investigators
often employ qualitative tests to determine whether the item leaches (or contains)
lead, and therefore warrants collection. Analysts need to be familiar with these
methods and techniques, since they are ultimately responsible for training investigators
to use these tests. An equivalent, FDA validated test kit does not exist for
cadmium. The presence of Cadmium is usually "signaled" by the presence
of rich yellow or red decorations on the food-bearing surface of the item. FDA
developed the Quick Color Test (QCT) for Lead (References 10, 11, 12). The QCT
test for lead, and similar forms of the test (e.g. the Rapid Abrasion Test (RAT),
Reference13), have been commercialized (e.g. LeadCheck SwabsTM, by Hybrivet,
Reference 14). The tests determine if an item bears leachable lead or the item
bears a leachable or non-leachable lead in the glaze or a decoration (Reference
13). Some of these commercial test kits have also been validated for testing
for the presence of lead in the solder of food cans, a prohibited practice (Reference
15). Test method LIB 4041 serves as a definitive test for detecting lead and
can be used to support regulatory action in canned products.
B. Prerequisites
None
C. Assignment
- Read the following documents, articles and methods: Compliance Program
Guide 7304.019B Toxic Elements in Foods (Domestic & Import); Gould et
al. (1988). Analytical Letters, 2145-2154; Capar, S. G. (1998,
August). Ceramic foodware lead screening using test kits. Laboratory Information
Bulletin, LIB No. 4127, 14, 1-8; Dolan, S.P. (1994). Journal
of AOAC International, 719-722; Capar, S. G., Anderson, D.L., Hughes,
D. D., Jacobs, R.M. (1996). Identification of lead solder on a metal can
seam. Laboratory Information Bulletin, LIB No. 4041, 12(12).
- Obtain articles to be tested from trainer (test items: lead containing
solder, food grade tin solder; ceramicware bearing lead containing glazes;
ceramicware bearing lead based decorations).
- Prepare reagents and obtain the test kits.
- Conduct qualitative tests on all the items noting color development.
- Demonstrate the presence of leachable lead in ceramicware.
- Demonstrate the presence of lead in ceramicware by the Rapid Abrasion Test.
- Demonstrate the presence of lead in solder.
D. Questions
- Which ions interfere with the test for leachable lead in ceramicware and
lead in tin-lead solders?
- What are the principal chemical reactions embodied in these test methods
and kits?
- How would someone utilize each test in selecting items ceramicware for
quantitative analysis?
6.2.2 Leachable
Lead and Cadmium from Ceramics by FAAS
A. Introduction
This exercise is designed to develop basic competence in the operation of the
flame atomic absorption spectrophotometer (FAAS) for the determination of Lead
(>1.0 ppm) and Cadmium (> 0.1 ppm). This method, and the related Graphite
Furnace AAS method EAM 4.2, form the basis for regulatory analyses for ceramicware.
B. Prerequisites
Volumetric and gravimetric procedures, good pipetting techniques and contamination
control practices.
C. Assignment
- Using EAM method 4.1 and the instrument manufacturer's manual, conduct
an analysis of lead and cadmium in ceramicware.
- Identify those instrument parameters that can affect the determination.
- Determine the highest sensitivity for lead and cadmium for this FAAS
instrument.
- Compare the sensitivities with those of the manufacturer’s specifications.
- Determine the characteristic masses for lead and cadmium.
- Determine the reporting limits for the two elements, as per EAM 4.1.
- Determine the linear ranges for these two elements.
- Prepare standards for the determinations.
- Prepare check standards that have traceability to a certified reference
solution.
- Obtain a six-unit sample of ceramicware and examine it for leachable
lead and cadmium using the flame atomic absorption method EAM 4.1.
D. Questions
- For the brand and model of instrument utilized, demonstrate the steps
employed to obtain maximum sensitivity for the two elements, and to eliminate
or minimize interference.
- What are the possible sources of interference?
- How does an instrument minimize or reduce these interferences?
- What steps could be used to correct background interference?
- What measures of instrumental performance verify instrumental "calibration"?
- Identify and give the acceptable range for other method quality control
measures that are utilized to assure accuracy and precision of analysis?
- Why are samples stored in the dark during leaching with 4% acetic acid?
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