Determination of Eight Steroid Hormones in Butter Samples by Liquid Chromatography-Tandem Mass Spectrometry
A method was developed for the determination of eight steroid hormones( estrone, α/β-estradiol, estriol, testosterone, epitestosterone, progesterone and testosterone propionate) in butter samples by gel permeation chromatography( GPC) purification-followed by liquid chromatography-tandem mass spectrometry( LC-MS/MS).The samples were first extracted by ethylacetate/cyclohexane( 1∶ 1, V/V) and the extract was later degreased by GPC column. Then, the GPC concentrate was separated using a C 18 column( 100 mm × 2.0 mm i.d., 3.0 μm) with gradient elution of acetonitrile/water. Finally, the steroid hormone components were qualitatively and quantitatively determined by mass spectrometer with electrospray ionization in multi reaction monitoring mode. Using matrix matched external standard method, good linearity in response could be obtained in the concentration range of 1.0- 20.0 μg/kg with correlation co-efficiency larger than 0.999. The detection limits of the method were 0.04- 0.30 μg/kg and the quantification limit was 1.0 μg/kg. At the spike levels of 1.0, 2.0 and 4.0 μg/kg, the recoveries of hormones were within the range of 64.1%- 110%, and the relative standard deviation( RSD) was less than 11%. The results show that the method is accurate and reliable, and meets the requirements for determination of 8 steroid hormones in butter samples.