Improvement of sample pretreatment for gas chromatographic determination of methylmercury in marine biota

✍ Scribed by Uwe Harms

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 306 KB
• Volume: 8
• Category: Article
• ISSN: 0268-2605
• DOI: 10.1002/aoc.590080715

✦ Synopsis

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.