The Mercury Group at BRL has developed a method modification to EPA Method 1630 that significantly lowers the methylmercury (MeHg) method detection limit (MDL). At 0.005 ng/L, or parts-per-trillion (ppt), this new low-level MDL is 4 times lower than the standard MDL of 0.02 ng/L. This new low-level MeHg method will be quite useful for applications such as environmental modeling and Total Maximum Daily Load (TMDL) studies where having a true, measurable result, rather than a ‘non-detect’ value, is essential.
An ultra-low MDL can be especially valuable to areas like the San Francisco Bay and Estuary, as well as surrounding tributaries, where MeHg concentrations can often be very low, but it can be critically important to have quantifiable MeHg values for environmental assessments. According to Don Yee of the San Francisco Estuary Institute, the ability to detect low concentrations and small differences is important because bioconcentration from water to tissues begins with uptake by small organisms like phytoplankton and the MeHg can be concentrated by a factor of 100,000 or greater.
To achieve this MDL, rigorous equipment preparation measures are taken prior to distillation followed by ethylation, trap pre-concentration, gas chromatography separation, pyrolytic combustion, and atomic fluorescence spectroscopy (CV-GC-AFS) using a Brooks Rand Instruments MERX-M analyzer. The ultra-sensitive MERX-M can quantify methylmercury at levels less than a tenth of a picogram.
Our very own Metals Chemist, Abby Rudd, co-authored an article recently-published in the journal Science of the Total Environment entitled Total- and Methyl-mercury Concentrations and Methylation Rates across the Freshwater to Hypersaline Continuum of the Great Salt Lake, Utah, USA (read abstract online). The article’s lead author, William P. Johnson, is a professor in the Department of Geology and Geophysics at the University of Utah in Salt Lake City. The study focuses on the methylation rate of mercury (Hg) in non-saline water, hypersaline water, and sediments from the Great Salt Lake and surrounding wetlands. The objective of the study was to correlate the methylation potential within specific environmental conditions (i.e., oxic, anoxic) to the Hg burden of the locale aquatic and terrestrial wildlife over time. This is a fascinating study that is a good read for any Hg or Great Salt Lake enthusiasts! Enjoy and thank you Abby!
Our President/CEO, Michelle Briscoe and VP of Operations, Annie Carter, are attending the Pacific Southwest Section meeting of AOAC International in Monterey, CA, February 18-19, 2015. Michelle will be chairing a session entitled “Food Testing for Metals – Recent Issues and Developments” and Annie will be presenting “2nd Annual International Intercomparison Study for Arsenic Speciation in Food”. See the Preliminary Program for more details.
European Winter Conference
Our Research Chemist, Tamas Ugrai, will be attending the European Winter Conference on Plasma Spectrochemistry in Münster, Germany, February 22-26, 2015. Tamas will be presenting a poster on the Results of the 2nd Annual International Interlaboratory Comparison Study for Arsenic Speciation in Food (see poster abstract).