Thin layer chromatographic and atomic absorption spectrophotometric determination of methyl mercury

A method is presented for determining methyl mercury that combines thin layer chromatography and atomic absorption spectrophotometry. The procedure is based on a previously reported method and entails isolating methyl mercury on a thin layer chromatogram, scraping adsorbent into an ignition tube, heating the tube, and moving the mercury vapor under vacuum into an absorption cell where it absorbs light at 253.7 nm. The procedure is sensitive to 0.7 ng Hg. Methyl mercury is extracted from biological samples by distilling, and then extracting with dithizone-chloroform. The extract is concentrated and applied to a thin layer chromatographic plate. The overall sensitivity of the method varies with sample size. For 100 g samples, the method is sensitive to about 8 ng Hg (as methyl mercury)/g (9 ppb).