Determination of naturally occurring oestrogens and androgens in retail samples of milk and eggs

The occurrence of the main steroid hormones (oestrone, 17α-oestradiol, 17β-oestradiol, 17α-testosterone, 17β-testosterone, dehydroepiandrosterone, 4-androstenedione), especially in milk and eggs, was investigated. An analytical method based on GC-MS/MS was developed for steroid measurement at an ultra-trace level in food products. The limits of detection for oestrogens were about 5 and 30 ng kg−1 in milk and eggs, respectively. For androgens, the limits of detection were around 10 and 50 ng kg−1 in milk and eggs, respectively. The method was applied to milk and egg samples collected in a French supermarket. In milk, oestrone was found at levels between 100 and 300 ng l−1, while 17β-oestradiol levels were estimated to be near 20 ng l−1. 17α-testosterone was found to be from 50 ng l−1 in skimmed milk to 85 ng l−1 in whole milk. In egg samples, oestrone and 17β-oestradiol were found at 1.5 and 0.9 µg kg−1, respectively, while 17α-oestradiol was found to be in lower concentrations (i.e. around 0.55 µg kg−1). ...