Evaluation of Direct Determination of Mercury in Whole Human Blood Using a Mercury Analyzer

A mercury analyzer (Model SMS 100) was evaluated for the direct determination of mercury in whole human blood samples. The instrument is based on sample combustion in an oxygen-rich furnace, elimination of interferences in a catalytic furnace, mercury concentration by amalgamation with gold, and the release of mercury vapor and its transport in a stream of oxygen to the measurement cell. Mercury determination is performed by atomic absorption spectrometry at 253.7 nm. In order to obtain complete combustion of the blood sample without loss of mercury, all operating conditions were optimized. The temperatures and times of the combustion step were critical to avoid spluttering of the sample. It was found that the samples of whole human blood, the certified reference material of human blood, and the aqueous standards showed different behavior in this step. The optimized condition for the combustion step was 650 degrees C for 60 seconds. The temperatures and times for the other steps were also optimized. The calibration and the analytical performance of the method were also studied. The detection limit obtained for mercury was 0.02 ng, and the relative standard deviations were between 1.1 and 3.2%. The proposed method is an interesting approach to the determination of mercury in whole human blood samples, because sample dissolution with wet digestion methods is not necessary, resulting in the ability to analyze an important number (approximately 7) of samples per hour.