Abstract
The behaviors of nanogram level of alkyl mercuric compounds including RHgX and RHgR (where R =alkyls and X=anionic groups) on gas chromatography have been studied. As the gas chromatographic columns were employed polydiethyleneglycol succinate 5% coated on Chromosorb W being packed in a stainless steel tubing (I) and the same liquid phase 1% coated on the rock crystal powder packed in a glass tubing (II), and they were maintained at 140°C150°C. When the column (I) was used, RHgX (X=I, Br, Cl) and RHgR were separated fairly well at the sample size above 10-5g. Below 10-8g, however, the compounds which had the same R group showed the same retention times regardless of difference in X groups (X=I, Br, Cl, CH3CO2, SO4, OH and dithizonate). These phenomena were not observed when the column (II) was used. Micro amounts of alkyl mercuric compounds are supposed to be thermally decomposed in the gas chromatographic column by catalytic action of column-composing materials (e.g. stainless steel, porous substrates). At the sample size of more than 10-5g, where the thermal conductivity detector is used, the major portion of injected sample passes through the column without suffering from thermal decomposition and give characteristic retention times. In this case, decomposed micro portions are not detectable. Decreasing the sample size below 10-8g, injected samples are completely decomposed and resulting products are detected by an electron capture detector. Though the mechanism of the decomposition has not been clear, it is assumed that a reaction that destroys the X group occurs in the column (I), forming another compound indifferent to X group.
