DETERMINATION OF METHYLMERCURY IN HUMAN HAIR BY CAPILLARY GC WITH ELECTRON-CAPTURE DETECTION

An analytical procedure was developed for the determination of methylm ercury in human hair using capillary gas chromatography with electron capture detection (GC-ECD). Hair samples are digested in alkaline solu tion/toluene in an ultrasonic bath at about 50 degrees C. After coolin g and treatment with hydrochloric acid (6 mol l(-1)) and a saturated s olution of copper sulphate, the organic phase is extracted with a cyst eine solution. Methylmercury is back-extracted in toluene by adding co pper sulphate and potassium bromide and analysed by GC-ECD using a DB1 7 capillary column. The practical detection limit of the method for me thylmercury is 50 ng g(-1) using 100 mg of hair sample. Column perform ances and injection reproducibility have been evaluated. Results on 13 samples of human hair are presented and related to the total mercury concentration. The method, consisting of the optimization of similar a nalytical procedures through improvements in the various steps, allows for sensitive and reliable quantitation of methylmercury in hair with good precision and accuracy.