Abstract
Purpose: To develop a simple but effective method for the quantitative analysis of estrogens in milk. Methods: Solid-phase extraction method was employed for the extraction of the estrogen from milk and high performance liquid chromatography-diode array detector (HPLC-DAD) was used for the determination of estrogen. Results: Optimal chromatographic conditions were achieved on an Eclipse XDB-C18 column at a flow rate of 0.8 mL/min at room temperature. The products were monitored using a DAD detector set at 280 nm. The retention time of the three main estrogens were 15 min with a gradient program of acetonitrile/water, from 0 to 3 min, holding 35 % acetonitrile; from 4 to 7 min, ramped to 55 % acetonitrile; from 8 to 20 min, maintained at 55 % acetonitrile. The results showed that the calibration curve had good linearity within the concentration range of 0.5 - 8.0 μg/mL with correlation coefficient (R2) in the range of 0.9929-0.9936. The limit of detection was in the range of 0.025 - 0.045 μg/mL while mean recovery of estrogen from milk samples varied from 92.6 to 104.1 %. Satisfactory precision was obtained both for intra-assay (RSD, 1.8 to 4.4 %) and inter-assay (RSD, 2.0 to 4.7 %). Conclusion: The proposed method is environmentally friendly, inexpensive and convenient, and should be helpful in analyzing estrogens in biological, environmental and food samples. Keywords: Solid-phase extraction, Milk, Estrogens, High performance liquid chromatography-diode array detector
Highlights
Estrogen is a kind of steroid hormone that can maintain female secondary sexual characteristics, with prominent compounds including natural estrone (E1), estradiol (E2), estriol (E3)
Increased risk of breast cancer has been reported in women with high circulating and urinary estrogen levels, as well as in those exposed to increased estrogen levels over time [5]
The linear equations of three kinds of estrogens were created according to peak areas versus working solution concentrations
Summary
Estrogen is a kind of steroid hormone that can maintain female secondary sexual characteristics, with prominent compounds including natural estrone (E1), estradiol (E2), estriol (E3) (see Figure 1). With the improvement in living standards, the consumption of foods high in protein, such as milk, is growing rapidly. Estrogen is used to promote animal growth, which causes a serious problem of estrogen being residual in milk and meat. These estrogens play a critical role in human carcinogenesis, such as breast, prostate, and ovarian cancer [1,2,3], and their special biological effect and potential hazard to human bodies has become another hot spot. Increased risk of breast cancer has been reported in women with high circulating and urinary estrogen levels, as well as in those exposed to increased estrogen levels over time [5]. Milk occupies a very important position in the human diet structure [4-
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