| The quality of dairy industry products is not optimistic in China. Based on epidemiological studies, there is growing concern among the general public about steroid hormones in milk. Dairy products have been implicated in the development of breast, uterine, and ovarian cancers; male reproductive disorders; adolescent and obesity. Steroid hormones were cited as the likely cause of these adverse health effects. Because of the difference of analysis methods and sample preparation methods, it is hard to get the accuracy results of steroid hormones, and also the number of samples analyzed and bovine physiological factors in each study can affect the contents of steroid hormones in whole milk samples. Due to the lack of effective control and inspection techniques, the quality and safety of dairy products has occurred frequently. The aim of this paper is to develop liquid chromatography-tandem mass spectrometry method for the determination of hormones residues in milk.Introduce the background, purpose and significance of this research, briefly introduce the basic knowledge of hormones and the research status of hormone detection technology in domestic and overseas.In this paper, a comprehensive analytical method based on liquid chromatographyelectrospray tandem mass spectrometry(HPLC-MS/MS) has been developed for the simultaneous determination of 22 hormones residues in milk. The sample was extracted with methanol, and then defatted with n-hexane. Sample concentration and purification were performed using HLB. The separation was performed on an Agilent ZORBAX SB-C18(2.1×150mm, 5μm) column. The qualification analysis was done by using retention time and the distribution of diagnostic ion pairs. The quantification analysis of the hormones was based on the peak intensity of parent ion and a fragment ion with a higher signal. The detection limits(LOD) of the method were from 0.10 to 1.20 μg/kg. The average recoveries of 22 steroid hormones(spiked at the levels of 100 and 200 μg/kg) ranged from 82.6% to 95.3%. The analytical precision of 22 steroid hormones in this newly developed assay is 4.2~11.3% and are within the acceptance criterion(less than 15%). Measurements for each compound in mixture of standard solutions were linear over a wide range(2.5~500 μg/L). Acceptable linear regression correlation coefficients between 0.9943 and 0.9998 were obtained for calibration. The method was simple, accurate, rapid and high sensitivity for the hormones residues determination.In this study, the final method was used to measure the 22 hormones residues in milk samples. Two types of milk samples, including bovine colostrum(n=10) and mature milk(n=90) were studied. They were collected in Sichuan. All cows were healthy and had no record of hormone drugs use. The results showed that the hormone concentration of mature milk was very little and only 3 of the hormones were detected. Meanwhile 8 kinds of hormones in bovine colostrum were detected using the option method. The concentration of hormones in colostrum was significantly higher than that in mature milk(P<0.05).Evaluating the potential safety of milk and to provide reference for further research... |
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