Determination of methylmercury in cryptogams by means of GC-AFS using enzymatic hydrolysis

Abstract

Since methylmercury is a highly toxic compound, there is undoubtedly a need for the monitoring of methylmercury in the ecosystem. However, its isolation from the organic matrix using an appropriate analytical procedure and sensitive detection technique are necessary due to trace levels of methylmercury in biomonitors. This study focuses on the determination of methylmercury in plant matrices by means of GC-AFS. The developed extraction procedure is based on the enzymatic hydrolysis of the matrix by cellulase, followed by the extraction of methylmercury in hydrochloric acid and the extraction of derivatized methylmercury into the organic phase. The limit of detection of methylmercury in environmental samples was 4μgkg−1. The method demonstrated sufficient precision, accuracy, and repeatability with respect to the determination of methylmercury in cryptogams. High contents of methylmercury (up to 60.9±4.4μgkg−1) were determined in cyanobacterial mats from James Ross Island (Antarctic Peninsula). Thus, freshwater lakes and wetlands in Antarctica can be sources of methylmercury for the local ecosystem.