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Improvement of sample pretreatment for gas chromatographic determination of methylmercury in marine biota
Author(s) -
Harms Uwe
Publication year - 1994
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.590080715
Subject(s) - chemistry , methylmercury , reagent , chromatography , sodium hydroxide , mercury (programming language) , gas chromatography , sample preparation , matrix (chemical analysis) , aqueous solution , hydrolysis , extraction (chemistry) , environmental chemistry , organic chemistry , bioaccumulation , computer science , programming language
Existing methods for analysis of methylmercury in biota consist of an initial extraction of the determinand at low pH with an organic solvent, followed by clean‐up and gas chromatographic determination. The complex biological matrix causes considerable interferences in the extraction process and makes the calibration of the method a difficult task. Results from the calibration method (standard addition) will only be correct if the calibrant added and the determinand are in the same chemical form and homogeneously distributed in the sample to be analysed. It is shown here that this presupposition is fulfilled if the sample is pretreated with an aqueous solution of sodium hydroxide (alkaline hydrolysis). In order to avoid uncontrolled losses of methylmercury at high pH, cysteine is added at the beginning of the pretreatment procedure. As a reagent forming strong complexes with mercury compounds, it protects methylmercury from disintegration during alkaline hydrolysis of the sample.