A stationary cold vapor method for atomic absorption measurement of mercury in blood and urine used for exposure screening

Abstract

A method is provided for rapid, accurate flameless atomic absorption Hg determinations in blood and urine used for exposure screening of mercury. Instead of the conventional apparatus requiring separate reduction and absorption containers, a one-piece reduction-absorption cell was fitted on the burner mount of an atomic absorption spectrophotometer. A five mL aliquot of the digested urine or blood sample was pipetted into the cell and one mL reductant added. The background corrected absorbance was recorded after three minutes of mixing. Heating the absorption cell at 60°C eliminated the formation of water vapor on the quartz windows of the tube. Sensitivity of the method was 1.0 ng which corresponds to a concentration of 0.2 ng/mL using a 5 mL sample size. The accuracy of Hg determinations in human blood and urine was confirmed by the method of standard additions of Hg to undigested samples. In order to test the applicability of the method to biological samples from Hg exposed individuals, rats were injected i.p. with 0.0 to 0.10 mg Hg as HgCl2. A dose related increase in Hg levels was observed in blood and urine collected at 24 hours after dosing. In addition, Hg was measured in human blood and urine samples obtained from 11 males not known to be recently exposed to Hg, indicating that the method is applicable to Hg exposure screening commonly used in industrial hygiene. The analysis can be conducted in less than 4 minutes each with a semi-automated sampling and cleaning capability and multiple Hg determinations performed on a single sample digest.