Changes in methylmercury concentration during storage: effect of temperature

The widespread presence of methylmercury (MeHg) in the environment and the potential toxicity and bioaccumulation in the food chain has stimulated a demand for accurate and sensitive methods for the determination of mercury compounds in water, sediments, fish and other biological samples. A capillary gas chromatographic method followed by atomic fluorescence spectrometry (GC–AFS) was used to determine changes in MeHg concentration with time during storage in methylene chloride and as affected by storage temperature. Results of our laboratory experiments showed that significant changes in MeHg concentrations occurred during a 15-day storage period. Decreases in the MeHg concentration with time were uniform and at the end of the 15-day storage period only about half the initial concentration (recoveries were between 40.2 and 51.2%) remained in samples stored at various temperature. These results draw attention to the need for immediate analysis of MeHg samples following extraction. Temperature of storage was not a significant factor in the change in MeHg concentration.