Determination of monomethylmercury from seawater with ascorbic acid-assisted direct ethylation

Author Posting. © Association for the Sciences of Limnology and Oceanography, 2014. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography: Methods 12 (2014): 1-9, doi:10.4319/lom.2014.12.1.We developed a technique to measure monomethylmercury (MMHg) concentrations from small volumes (180 mL) of seawater at low femtomolar concentrations using direct ethylation derivitization, decreasing the required volume by 90% from current methods while maintaining a 5 fM detection limit. In this method, addition of ascorbic acid before derivitization of MMHg allows for full recovery of MMHg from the seawater matrix without the need for sample distillation or extraction. The small sample size and relative ease of detection are ideal both for shipboard as well as shore-based measurements of preserved MMHg samples. Combined with shipboard determination of dimethylmercury (DMHg) and elemental mercury (Hg(0)), this method can be used to determine full marine mercury speciation.This research was supported by a National Science Foundation grant (OCE-1031271) awarded to C. H. L. and Mak Saito and a Graduate Research Fellowship awarded to K. M. M