Determination of cadmium in urine by graphite-furnace atomic absorption spectroscopy

A simple procedure for graphite-furnace atomic absorption analysis of cadmium in urine, based on the use of a temperature-controlled heating unit, is described. The temperature of the carbon rod is measured by resistance and controlled by electronic feedback. We studied the influence of various heating times and temperatures of ashing and atomization, as well as suitable diluents. Urine samples were diluted with an equal volume of 0.3 mol/liter HNO3, and 1 to 5 microliter of the mixture was analyzed, with background correction. Signals were evaluated electronically, giving values for integrated peaks as well as for peak heights. The detection limit was 1.2 nmol/liter. The method appears to be accurate and reproducible. The CV averaged 8% for concentrations in the range 20 to 100 nmol/liter. Correlations with a chelation-extraction method was 0.994.