Simultaneous determination of methylmercury (MeHg) and ethylmercury (EtHg) in natural waters was developed using propylation-headspace (HS)-GC/MS. Sodium tetra (n-propyl) borate was used as a propylating agent. Mercury compounds were extracted as dithizon-complex by toluene, then back extracted into water by evaporating the toluene. The mercury species in the water was propylated in the headspace vial and analyzed with HS-GC/MS. The limits of detection of MeHg and EtHg for 1 L water sample were 0.005 and 0.007 ng/L, respectively. The average recoveries of MeHg and EtHg, performed for several natural water samples, were 91 and 87%, respectively. Using this method, determinations of a small amount of MeHg and EtHg in natural waters are applicable.
