Furnace atomic absorption--a method approaching maturity.
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Food Analysis↗
Biomedical subjects
M L Kaiser
Publications and source records attributed to M L Kaiser.
Food analysis for lead using furnace atomic absorption and a L'vov platform.
Furnace atomic absorption is a very sensitive method for determination of lead and other trace metals in a variety of samples, but it is prone to matrix interferences. A major improvement in the method is achieved by the use of a L'vov platform, a small piece of graphite placed inside the furnace tube, onto which the sample solution is pipetted. The temperature of the platform rises more slowly than that of the tube wall during the atomization cycle, and sample vaporization is delayed until the furnace atmosphere is at a high and nearly constant temperature. The resulting atomization behavior is more consistent and less matrix-dependent for numerous analyte elements, including lead. Results are further improved by addition of ammonium phosphate to all samples and standards as a matrix modifier. For example, in comparing analyte sensitivity (slope of the absorbance vs concentration curve) in a variety of food sample types to the sensitivity in dilute HNO3, the average lead response showed 60 +/- 15% suppression due to the sample matrices. Use of the L'vov platform and matrix modifier virtually eliminated the suppression and improved the precision.
Food Analysis↗
Evaluation of cryogenic impact grinding technique for powdering whole fish for metal determinations.
A cryogenic grinding technique, which involves brittle fracture of samples by impact pressure, was evaluated for the final reduction of whole-fish samples for subsequent metal determinations. The technique incorporated a number of desirable features: protection of heat-labile components; incorporation of lyophilization to facilitate handling and storage; requirement of few procedural steps; short grinding time per sample; and easy, rapid cleanup of equipment. Particle size in the ground powder was less than 100 microns. Problems associated with the technique were contamination of fish samples with Cr, Fe, Mo, and Ni; limited size of the grinding container; and powder clumping caused by the presence of lipids. Approaches to alleviate these problems are discussed.
Animals↗