Determination of mercury in blood by cold vapor atomic spectrometry

The determination of mercury in biological matrices, such as blood, urine, and hair, is an important indicator in the assessment of mercury contamination in the environment and at the work place. Non-reactive alkyl compounds with stannous salts have been used by some authors for the differential determination of inorganic and organic mercury in cold vapor atomic spectrometry (CVAAS). However, this procedure does not allow for complete digestion of blood, which is an essential condition for flow injection systems in order to avoid the generation of foam that would block the flow of the carrier gas. Thus, a suitable and easy-to-use routine method for the determination of mercury based on appropriate sample digestion, followed by automated flow injection cold vapor reduction with NaBH 4 , has been developed. The method was optimized by varying the carrier gas flow rate and the concentration of the diluent solution. A carrier flow rate of 75 mL/min provides a high enough absorbance peak with adequate resolution in peak shape. Best results were obtained by diluting the digested samples and aqueous standards with 10% nitric acid and 20% sulfuric acid. The limit of detection for whole blood was 0.95 nmol/L, with a linear range up to 600 nmol/L. To determine the precision and accuracy of the method, three levels of Seronorm trace elements whole blood were analyzed. The precision had a mean value of 3.7%. The accuracy was confirmed with the analysis of 24 samples of unknown concentration from the Quebec Interlaboratory Quality Control Program.