Determination of conjugated estrogens in human urine using carrier-mediated hollow-fiber liquid phase microextraction and LC-MS/MS

AbstractThe extraction conditions of the conjugated estrogens, including estrone-3-glucuronide (E1-3G), 17β-estradiol-3-glucuronide (E2-3G), and 17α-ethynylestradiol-3-glucuronide (EE2-3G), were optimized using carrier-mediated hollow-fiber liquid phase microextraction (HF-LPME) and then applied in the analysis of human urine samples. The optimal extraction conditions were as follows: organic phase composed of 20% (w/w) tri-octylamine (TOA) in 1-octanol; 2 M NaCl as the acceptor phase; 800 rpm of agitation; and 50 min of extraction time. The extraction efficiency of carrier-mediated LPME was 11 times higher than that of the three-phase LPME. Estrogens and their conjugates in urine samples from pregnant and non-pregnant women were extracted and analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). The results showed that carrier-mediated HF-LPME had good recoveries and linearity in the calibration curve. Estrogens in pregnant and non-pregnant women were mainly excreted in a conjugated f...