determination of hormones residues in milk by gas chromatography-mass spectrometry

The article presents the use of gas chromatography-mass spectrometry (gc-ms) technique in a method for the determination of 18 anabolic hormones from synthetic stilbenes, steroids and resorcylic acid lactones (rals) groups in raw milk and milk powder. sample preparation consisted of liquid-liquid extraction with diethyl ether and purification by solid phase extraction (spe). prior to instrumental analysis, the reaction of derivatisation with the heptafluorobutyric anhydride or n-methyl-n-trimethylsilyltrifluoroacetamide was performed. method validation was carried out according to the required performance criteria of the commission decision 2002/657/ec. the apparent recovery of all analytes at 1 μg l−1 (kg−1) level was ranged between 70.4 and 119.4 % with the coefficients of variation values less than 30 %. the decision limits (ccα) and the detection capabilities (ccβ) were in the range of from 0.11 to 0.44 μg l−1 (kg−1) and from 0.19 to 0.75 μg l−1 (kg−1), respectively. the procedure has been accredited and successfully applied as a screening method for the presence of hormone residues in the study of commercial samples of milk.