Science & Research

Volume IV - 6.2 Exercises

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Orientation and Training
Food and Drug Administration

Section 6 - Elemental Analysis

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).
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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


C. Assignment

  1. 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).
  2. 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).
  3. Prepare reagents and obtain the test kits.
  4. Conduct qualitative tests on all the items noting color development.
  5. Demonstrate the presence of leachable lead in ceramicware.
  6. Demonstrate the presence of lead in ceramicware by the Rapid Abrasion Test.
  7. Demonstrate the presence of lead in solder.

D. Questions

  1. Which ions interfere with the test for leachable lead in ceramicware and lead in tin-lead solders?
  2. What are the principal chemical reactions embodied in these test methods and kits?
  3. How would someone utilize each test in selecting items ceramicware for quantitative analysis?

6.2.2 Qualitative analysis by XRF

A. Method (SOPs indicated below are located in e-room)

Elemental Analysis Using the Thermo Quant-X X-Ray Fluorescence Instrument
Bruker Tracer III X-Ray Fluorescence Analyzer
Detection and Confirmation of Toxic Element Using the Innov-X-X-5000 Field Portable X-Ray Fluorescence Analyzer

6.2.3 Leachable Lead and Cadmium from Ceramics by GFAAS

A. Method

Elemental Analysis Manual (EAM) 4.2., Determination of Leachable Lead and Cadmium from Ceramicware by Graphite Furnace AAS,

B. Prerequisites

Volumetric and gravimetric procedures, good pipetting techniques and contamination control practices.

C. Assignment

  1. Using EAM method 4.2 and the instrument manufacturer's manual, conduct an analysis of lead and cadmium in ceramicware.
  2. Identify those instrument parameters that can affect the determination.
  3. Determine the highest sensitivity for lead and cadmium for this FAAS instrument.
  4. Compare the sensitivities with those of the manufacturer’s specifications.
  5. Determine the characteristic masses for lead and cadmium.
  6. Determine the reporting limits for the two elements, as per EAM 4.2.
  7. Determine the linear ranges for these two elements.
  8. Prepare standards for the determinations.
  9. Prepare check standards that have traceability to a certified reference solution.
  10. Obtain a six-unit sample of ceramicware and examine it for leachable lead and cadmium using the graphite furnace atomic absorption method EAM 4.2.

D. Questions

  1. 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.
  2. What are the possible sources of interference?
  3. How does an instrument minimize or reduce these interferences?
  4. What steps could be used to correct background interference?
  5. What measures of instrumental performance verify instrumental "calibration"?
  6. Identify and give the acceptable range for other method quality control measures that are utilized to assure accuracy and precision of analysis?
  7. Why are samples stored in the dark during leaching with 4% acetic acid?

6.2.4 Leachable Lead and Cadmium from Ceramicware by ICP-OES

A. Method

Elemental Analysis Manual (EAM) 4.6.
Inductivly Couled Plasma-Atomic Emission Spectrometric Determination of Cadmium and Lead Extraced from Ceramic Foodware

6.2.5 Mercury (total) in Seafood by CVAAS

A. Method

EAM 4.6 (method presently in draft status)
Determination of Mercury (total) in Seafood by Cold Vapor AAS.

6.2.6 Multi-Element, Simultaneous Sequential/Quantitative Analysis of Foods by ICP-MS

A. Method

EAM 4.7 (method presently in draft status)
Multi-Element, Simultaneous Quantitative Analysis of Foods by ICP-MS

Page Last Updated: 03/18/2016
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