Mercury Speciation (Hg)
The difference in toxicity, mobility, and treatability of mercury is directly predicated on its molecular form. Many regulations associated with food, water, and drug safety focus on methyl mercury using promulgated method EPA 1630. Although EPA Method 1630 has been proven to have excellent performance for a vast array of sample matrices it is limited to providing quantitative results for monomethyl mercury and monoethyl mercury. In order to support more diverse chemical systems and complicated mercury species Brooks Applied Labs has developed state of the art analytical methods coupling liquid chromatographic systems with in-line cold vapor reduction and inductively coupled plasma mass spectrometry.
Mercury Speciation Services Available:
Methylmercury
The potential for mercury contamination to become an even more serious human and environmental health issue largely depends on whether the location in which it arrives is favorable to the conversion of inorganic mercury to the significantly more toxic organic form of methylmercury.
Research suggests that as inorganic mercury settles into the sediments of aquatic systems, prevailing anaerobic microorganisms are largely responsible for this methylation process. Particularly common locations for the methylation of mercury are wetlands, low-alkalinity lakes, organic-acid rich systems, recently flooded areas, and streams where severe fluctuations occur.
Responsible for more than three-quarters of all fish consumption advisories in the United States, methylmercury is a pollutant of the highest concern and it is likely that it will become a requirement that it be widely monitored. Brooks Applied Labs has methods for methylmercury detection from numerous matrices including all water types, soils and sediments, tissue samples, and human biomonitoring samples (blood, urine, hair, etc.)
Ethylmercury
Ethylmercury has known neurotoxic effects that are similar to those of methylmercury, but unlike methylmercury, its tissue deposition and clearance rates in organisms are not well-understood. Brooks Applied Labs has developed methods for the effective detection of ethylmercury in water, tissue, and blood samples.
Inorganic Mercury
Inorganic mercury has a much lower toxicity than monomethyl, monoethyl, or dimethyl mercury but it plays a key role in bioavailability for lower trophic organisms, fate and transport in ecosystems, as well as treatability in industrial settings. Often time’s inorganic mercury will be associated with particulate and is readily removed from solution. More complicated systems can have active sulfhydryl sites, such as humic or fulvic acids or proteins, which induce adsorption and formation of labile species. Understanding the chemical nature of the sample with inorganic mercury can play a key role in the overall risk of an environment as mercury moves up the food chain.
Total Volatile Mercury
Elemental mercury is volatile and its vapor is emitted into the atmosphere where it will be eventually converted by photovoltaic oxidation into inorganic mercury. It is then deposited, mostly through precipitation, onto land or water bodies. Easily mobilized in water, inorganic mercury from deposition can reach larger aquatic systems. Dimethylmercury is another volatile and gaseous form of mercury that is highly toxic and can be released from landfill sites. These compounds are measured using Brooks Applied Lab’s method for total volatile mercury analysis. While this method has a very short holding time and rigorous sample collection and shipping protocols, it provides one of the only ways to accurately measure low levels of elemental mercury from water samples.
Acid-Labile Mercury
Some researchers in our field believe that aqueous divalent mercury is only a semi-quantitative analyte, and there are many different operationally-defined methods for its determination. These methods can produce a wide range of results for different sample types. Because there are so many variables when looking at this operationally-defined category of Hg species, it is important to have a consistent procedure that is rigidly followed. Brooks Applied Labs’ method for acid-labile Hg provides for a consistent measurement that is often used as a surrogate for Hg(II) or inorganic Hg analysis. Brooks Applied Labs’ method is operationally-defined as the available mercury after 21-28 days of preservation to pH 2 with HCl.
Pore Water Extractions
The extraction of interstitial waters from sediment samples prior to the analyses of mercury or methylmercury requires particular precautions to prevent both potential contamination and species conversion. Brooks Applied Labs has developed custom procedures that allow the collection of pore water extractions while maintaining the integrity of the sample.
Elutriate Generation
Effectively evaluating the effects of dredging projects often entails replicating elutriate generation under the controlled conditions of the laboratory. Where mercury or methylmercury analyses are required, Brooks Applied Labs has developed custom procedures that ensure an accurate representation of the physical processes that occur without compromising the integrity of the sample through inadvertent contamination.
Mercury Species Analyzed by EPA Method 1630
- Monomethyl Mercury [MMHg]
- Monoethyl Mercury [EtHg]
Selected Mercury Species Supported by Hyphenated ICP-MS Techniques
- Monomethyl Mercury [MMHg]
- Monoethyl Mercury [EtHg]
- Inorganic Mercury [Hg(II)]
Mercury Species Associated with
- Humic Acids
- Fulvic Acids
- Proteins
Matrices Supported
- Water (wastewater, surface water, well water, seawater, impacted water, industrial process water, mine runoff)
- Soil
- Sediment
- Coal Combustion Byproducts (e.g. fly ash)
- Tissue (nearly all)
- Food (nearly all vegetable, meat, and grains)
- Nearly all aquatic organisms
- Nearly all terrestrial organisms
- Nutraceuticals
- Supplements
- Textiles
- Solvents
- Chemicals (acids, bases, etc.)
- Air
- Petroleum and Petroleum Products
At Brooks Applied Labs, we have both the innovation and the expertise to provide you with ultra-low mercury and mercury speciation analyses for virtually any matrix type. Please contact us to find out which mercury test is the appropriate method choice for your samples.