Within-run Coefficients Of Variation Research Articles

A Simplified Determination of Urinary Cadmium, Lead, and Thallium, with Use of Carbon Rod Atomization and Atomic Absorption Spectrophotometry

Abstract Lead, cadmium, and thallium are determined in a single 3-ml urine sample. The three metals, simultaneously chelated with sodium diethyldithiocarbamate, are extracted (at pH 3-7) into methyl isobutyl ketone (isopropylacetone), and the carbon rod atomizer, in conjunction with atomic absorption spectrophotometry, is used to analyze the extracts. Small sample requirements (1.6 µl) permit the extraction to be carried out in small-volume disposable glassware, with use of disposable pipets. Within-run coefficients of variation were all less than 5%; recovery ranged from 96-106%. Several normal urinary constituents, added in excess, negligibly affected recoveries. Ethylenediaminetetraacetate in the urine inhibited recovery of lead; this was reversed by adding excess calcium to the urine before extraction. The method of standard additions was used to compensate for differences between standards and unknowns caused by matrix effects.