Rapid method for removal of inorganic mercury contained in methylmercury preparation using CM-Sephadex minicolumn.

Methylmercury is one of the most typical environmental pollutants, and many studies on its toxicity and metabolism have been performed. A methylmercury solution prepared for experiments generally contains a trace amount of inorganic mercury. To obtain accurate experimental results an inorganic mercury-free methylmercury preparation should be employed for toxicological studies, because behavior of inorganic mercury in animals is quite different from that of methylmercury.1,2) We describe here a rapid and simple method for removal of inorganic mercury in methylmercury preparation using a CM-Sephadex minicolumn. 203HgC12 solution and CH 3203HgC1 powder were purchased from Amersham, Int. Corp. CH3203HgC1 powder was dissolved in 10 mM sodium carbonate buffer (pH 9.2), and the solution was used after one week storage at 4•Ž. 203HgC12 solution was diluted with non-radioactive mercuric chloride solution containing 10 mM sodium carbonate (pH 9.2) . One milliliter of 1 mM 203HgC12 and/or CH32°3HgC1 solution was applied on the CM-Sephadex C-25 column (5 •~ 45 mm) equilibrated with 10 mM sodium carbonate buffer. This column was eluted with 10 mM sodium carbonate buffer at a flow rate of 1 m//min, and each 2-ml eluate fraction was collected in a tube. Amounts of organic and inorganic form of 203Hg in the eluate and those retained in the column after the elution were selectively determined by the method of Omata et al.3 This selective determination method is based on complete extraction of methylmercury with benzene from the solution