PROBLEMS ENCOUNTERED DURING THE DEVELOPMENT OF A METHOD FOR THE SPECIATION OF MERCURY AND METHYLMERCURY BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COUPLED TO INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A study was carried out to develop a method for the determination of m ethylmercury and inorganic mercury by coupling HPLC to ICP-MS, During the course of this work it was noted that the use of stainless-steel c omponents in the HPLC system led to adsorption of the mercury compound s, which was more pronounced with mercury(II) chloride than methylmerc ury. In particular, the use of a stainless steel sample loop led to la rger peaks for both compounds, but particularly inorganic mercury, com pared with a PEEK loop, The type of loop used had no effect on the sep aration of these compounds on an ODS column using a mobile phase compo sed of 10 mM tetrabutylammonium bromide and 60% methanol, However, bot h of the two ODS stainless-steel Columns tested adsorbed the compounds to some degree, leading to a slow bleed of mercury, The use of compon ents made,vith materials other than stainless steel, e.g., PEEK sample loops and glass-lined columns, and inclusion of a sulfur ligand in th e eluent (2-mercaptoethanol) reduced these problems significantly.