Simplified Determination of Cadmium, Lead and Chromium in Estuarine Waters by Flameless Atomic Absorption

Abstract

A simplified, sensitive and rapid method for determining low concentrations of cadmium, lead and chromium in estuarine waters is described. To minimize matrix interferences, nitric acid and ammonium nitrate are added for cadmium and lead; nitric acid only is added for chromium. Then 10, 20 or 50 μ1 of the sample or standard (the amount depending on the sensitivity desired) is injected into a heated graphite atomizer, and specific atomic absorbance is measured. Analyte concentrations are calculated from calibration curves for standard solutions in demineralized water for chromium or an artificial seawater medium for lead and cadmium. Analytical ranges (μg1⁻¹) with two instruments were linear at 0.1-1.0 and 1.G10 for cadmium, 4-20 and lCb-100 for lead. and 0.2-5 and 5-100 for chromium. Detection limits (μg⁻¹) were 0.1 for cadmium, 4 for lead and 0.2 for chromium. For cadmium (0.5 and 5 μg ⁻¹), lead (4 and 50 μgl⁻¹) and chromium (1 and 10 μgl⁻¹) in half-strength artificial seawater, the relative standard deviations (n = 10) were 20 and 9.5, 18 and 10.4 and 25 and 8.0% respectively. The proposed method was used to determine cadmium, lead and chromium in 52 estuarine water samples. Cadmium was detected in 11 samples and ranged from 0.5 to 9.7 μgl⁻¹, no lead was detected in any of the samples, and chromium was detected in 5 samples at concentrations from 0.5 to