Analysis of mercury-containing protein fractions in brain cytosol of the maternal and infant rats after exposure to a low-dose of methylmercury by SEC coupled to isotope dilution ICP-MS

The mercury-containing protein fractions in the brain cytosol of the maternal and infant rats after exposure to low-dose of methylmercury chloride (0.3 mg Hg kg^-1 day^-1) were analyzed by a SEC-ICP-MS method with the postcolumn isotope dilution analysis. The enriched spiking including ³⁴S, ⁶⁵Cu, ⁶⁷Zn and ¹⁹⁸Hg was continuously added into the eluate from the HPLC column and then the isotope-diluted fractions were on-line measured by ICP-MS. Therefore, the absolute amounts of sulfur, mercury, zinc and copper in the eluted protein fractions could be attained after calculation of the corresponding peak areas in the mass flow chromatogram. Five mercury-containing protein fractions were monitored in the maternal sample, whereas only one was in the infant sample. The mercury content in the infant sample was about 10 times lower than the one in the maternal sample. In the meantime, two copper- and four zinc-containing fractions were found in both maternal and infant samples. The detection limit for S, Cu, Zn and Hg are 11, 0.1, 1.5 and 0.2 ng, respectively. The results demonstrate that different mercury-containing protein fractions may exist in brain cytosol between maternal and infant rats and the quantitative calculation may be helpful for the toxicological study.