GC-MS determination of anabolic steroids after multi-immunoaffinity purification

For many years, EC regulations have prohibited the use of anabolic agents i n food-producing animals. Multiple screening methods have been published, b ut some lack specificity and some are difficult to apply when screening for unknowns in surveillance programmes, This paper presents a new and powerfu l technique, combining multiresidue immunoaffinity chromatography and GC-MS , for the simultaneous identification and semi-quantification of various an abolic steroids in urine and faeces samples of bovine origin. It should red uce the cost, time and effort of screening by limiting the number of tediou s clean-up steps and analyses required. A preliminary extraction step is ap plied to the individual biological specimens: solid-phase extraction follow ed by enzymatic digestion in the case of urine samples and a single liquid extraction step for faeces. This step is followed by a first clean-up step involving both a solid-phase column and a rapid RP-HPLC separation. The ind ividual biological fractions (urine or faeces) are further purified on a mu ltiresidue immunoaffinity chromatographic gel (MIAC-steroids-CER) so as to decrease interferences due mainly to background signals. A final trimethyls ilyl derivatization is followed by the analysis of the biological samples b y a sensitive and specific GC-MS procedure.