Development and validation of a method for simultaneous analysis of the boar taint compounds indole, skatole and androstenone in pig fat using liquid chromatography–multiple mass spectrometry

Boar taint in entire male pigs remains a problem for fresh pork production. Since castration of pigs will be prohibited in the future on animal welfare reasons, attempts are made to detect boar taint pre and post mortem. Post mortem techniques focus on simultaneous quantification of the three boar taint substances by one simple and reliable method. In this study a liquid chromatographic multiple mass spectrometric (LC-MS(n)) method has been developed and validated for the simultaneous determination of indole (2,3-benzopyrrole, ID), skatole (3-methylindole, SK) and androstenone (5alpha-androst-16-en-3-one, AEON) in pig fat samples. Sample preparation was kept as short as possible, since a single extraction method for structurally different indols and steroids was seeked after. Analytes were extracted from the fat matrix by methanol and clean-up consisted of freezing the extract in liquid nitrogen followed by a filtration step. The analytes were chromatographically separated on a Symmetry C(18) column. Recoveries for ID, SK and AEON, as calculated from fortified fat samples using 2-methylindole (2-MID) as internal standard, were 96, 91 and 104%, respectively. However, matrix interferences were encountered determining the androstenone levels in fat. Linearity, determined in fat samples, was in the range of 50-1600 microg kg(-1) for the indolic compounds and 125-2000 microg kg(-1) for the steroid AEON. The correlation coefficients (R(2)) of the calibration curves were 0.998 for ID, 0.997 for SK and 0.810 for AEON.