Determination of Organomercury Compounds from Microbiologically Mediated Mercury Release Experiments Using Gas Chromatography with SPME Sample Introduction after Boroethylation, Boropropylation, or Borophenylation

摘要

Mercury offgassing from coal combustion by-products (CCBs) is of great interest, especially for agricultural and soil stabilization applications. In these cases, microbiologically mediated mercury release can result from methylation reactions. The Energy & Environmental Research Center (EERC) has developed a method of sampling gas streams and headspace gas for determination of dimethyl mercury and methyl mercuric chloride. A derivitization method using sodium tetraethyl, propyl, or phenyl borate is carried out prior to capture with a solid-phase microextraction (SPME) fiber coated with polydimethylsiloxane. Detection limits on the order of 50 to 100 picograms have been achieved, and lower detection limits are possible with further refinement of the method. Organomercury species have been detected in microbiologically mediated experiments using coal fly ash. Anaerobic conditions promoted greater levels of organomercury generation than aerobic conditions.