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 contaminat ion in the environment and at the work place. Non-reactive alkyl compounds with stannous salts have been used by some aut hors for the differential determination of inorganic and organic mercury in cold vapor atomic spectrometry (CVAAS). However, this procedure does not a llow for complete digestion of blood, which is an essential condition for f low injection systems in order to avoid the generation of foam that would b lock the flow of the carrier gas. Thus, a suitable and easy-to-use routine method for the determination of mercury based on appropriate sample digesti on, followed by automated flow injection cold vapor reduction with NaBH4, h as been developed. The method was optimized by varying the carrier gas flow rate and the conce ntration of the diluent solution. A carrier now 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 standard s 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 Sero norm trace elements whole blood were analyzed. The precision had a mean val ue of 3.7%. The accuracy was confirmed with the analysis of 24 samples of u nknown concentration from the Quebec Interlaboratory Quality Control Progra m.