Abstract
A hyphenated system for methylmercury based on a gas chromatograph (GC) coupled with an atomic fluorescence spectrometric (AFS) detector equipped with an online purge and trap as a preconcentrator was made. Operating parameters for the whole system were optimized and analytical performances of the system are verified by quality control chart for stability. Organomercurial compounds in an aqueous sample were in-situ ethylated and purged to a trap in-line with a separation device instead of conventional off-line solvent extraction. A 100 mL aqueous sample containing methylmercury in an impinger was mixed with sodium tetraethylborate at pH 5.0. The forming volatile ethylmethylmercury was purged for 30 minutes with the assistance of an Ar flow and trapped into a Tenax sorbent. The trap was then heated to release volatile compounds including ethylmethylmercury into a GC-AFS for separation and detection. The instrumental detection limit was 4.8 pg Hg/L. The method can therefore be applied for the determination of methylmercury in water samples at ultra – trace.
Highlights
Mercury (Hg) is one of the most serious global pollutants that affects human and ecosystem health
gas chromatography (GC) – atomic fluorescence spectrometry (AFS) has been still commonly used for methyl mercury analysis, mainly owing to its high sensitivity comparable to GC-inductively coupled plasma mass spectrometry (ICPMS) and low cost
The working parameters for the gas chromatograph, the pyrolyzer and the make-up and shealth flow rates AFS detector were re-optimized based on previous studies for maximum sensitivity and best resolution [9]
Summary
Mercury (Hg) is one of the most serious global pollutants that affects human and ecosystem health. Much effort has been expended in determining the methylmercury in environmental samples. GC – AFS has been still commonly used for methyl mercury analysis, mainly owing to its high sensitivity comparable to GC-ICPMS and low cost. This technique is properly possible to be conducted in Vietnam. Preconcentration is the most important factor in determining methylmercury due to its extremely low concentration in water sample. For low level CH3Hg+ analysis, the most widely used technique is purge and trap gas chromatography (GC) coupled with an element specific detector, such as atomic fluorescence spectrometry (AFS) or inductively coupled plasma mass spectrometry (ICPMS)
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