Reduction of Organic Mercury in Water, Urine, and Blood by Sodium Borohydride for Direct Determination of Total Mercury Content

We haveestablishedtheoptimalconditionsfor use of sodium borohydride as the reducing agent before the direct determi-nation of mercury in water, urine, and blood by atomic absorption spectroscopy. We evaluated the effects ofpH, temperature, and cupric sulfate concentration on the direct determinationof both organic and inorganic compounds of mercury. Accurate and precisequantification of mercury requiresthatthe pH be between 9.3 and 9.5, the reaction temperatureabove 25 #{176}C,the reactiontime longerthan 1 mm, and, for urine samples only,the cupricsulfateconcen-tration 10 &mol/L. The detection limit of the method is 1 to 2 ng and the precision(CV)is3.8 % forbloodand 4.0 % for urine. Additional Keyphrases: atomic absorption spectroscopy trace elements toxicology conditions for complete reductio