Rapid Determination of Mercury in Seafood in an Introductory Environmental Science Class

Abstract

Environmental mercury has been a media topic over the past decade, with particular concern over its bioaccumulation in seafood. However routine analysis in the undergraduate laboratory is lacking owing to experimental challenges with traditional methods. Modern instrumentation alleviates these challenges and makes it possible to bring this relevant topic to the undergraduate laboratory, even for nonmajor students. We present the results for mercury content in various seafood samples obtained by students in an entry-level nonmajors chemistry course via direct mercury analysis and demonstrate how this important environmental contaminant can be easily determined in a meaningful laboratory experience.

Mercury in Environmental and Biological Samples Using Online Combustion with Sequential Atomic Absorption and Fluorescence Measurements: A Direct Comparison of Two Fundamental Techniques in Spectrometry

“…A schematic of the instrument is given in Figure . Mercury analysis by combustion-AAS has been described elsewhere − . Briefly, samples are weighed to the nearest 0.1 mg in a nickel boat that is automatically introduced into the instrument’s combustion tube.…”

“…These instruments have been purchased by colleges and universities in the United States and elsewhere and have been incorporated into chemistry curricula. 3 Moreover, the instruments have a small footprint and are user-friendly, requiring little time to train students (5). As noted earlier, for this activity, the combustion-AAS system is coupled directly to the AFS system so that the mercury exiting the combustion-AAS unit is carried directly to the gold traps of the AFS instrument, instead of a hood as normally would take place.…”

“…Mercury has one of the most complex and interesting biogeochemical cycles among the elements. 5 It is a persistent, mobile, and highly toxic heavy metal pollutant with its biogeochemistry being dominated by its chemical form (speciation) and redox state (9). The element exists in various inorganic and organic forms in the environment, most notably elemental mercury (Hg 0 ), inorganic ionic mercury (Hg 2þ ), and organometallic monomethylmercury (MeHg).…”

“…An increasing number of chemistry and biochemistry departments are utilizing nontraditional instrumentation in their analytical and environmental chemistry courses . One class of instruments that have been shown to generate student enthusiasm and provide a number of learning opportunities is mercury analyzers based on sample combustion, amalgamation with gold, and AAS .The technique, also called thermal decomposition-AAS, is commonly used to measure mercury in environmental and biological samples − ; it is rapid, requires no sample pretreatment (e.g., no acid digestions), and is available in instrumentation by multiple manufacturers 2. The principle behind the instrument, briefly, is that mercury, contained in a sample, is separated from the matrix through combustion, concentrated by amalgamation with gold, and subsequently thermally released in a pulse and carried into an atomic absorption spectrophotometer.…”

Determination of Mercury in Fish: A Low-Cost Implementation of Cold-Vapor Atomic Absorbance for the Undergraduate Environmental Chemistry Laboratory

“…Armenta et al, Cizdziel, and Jenkins et al all describe laboratory exercises measuring mercury using commercial mercury analysis systems. Rice et al suggest using a commercial direct mercury analyzer to study concentrations of mercury in locally caught fish …”