A Simple and Robust Method for Determination of Alkylmercury in Seawater and Industrial Wastewater by Phenylation Pretreatment Combined with GC-MS

For determination of methylmercury (MeHg) and ethylmercury (EtHg) in seawater and industrial wastewater, a simple and robust analytical method was developed based on phenylation and solvent extraction followed by GC-MS measurement. Alkylmercury compounds were directly phenylated with sodium tetraphenylborate in water and extracted into toluene. The method detection limits obtained for MeHg and EtHg in pure water were 53.3 and 33.5 ng Hg L−1, respectively, which are almost 10 times lower than the environmental quality standards for water pollution in Japan (EQSJ): 0.5 μg Hg L−1. The recoveries of alkylmercury compounds from seawater and four kinds of industrial wastewater except for EtHg from treated wastewater of an optic lens factory were satisfactory (>90%) at 1- or 4-fold concentrations of the EQSJ. Contrarily, the low recovery of EtHg from the treated wastewater (75.4 ± 4.7%) was found to be caused by the rapid decomposition of EtHg into inorganic mercury.