Determination of Residues of Steroid Hormone Drugs and Related Drug in Surface Water Around Medical and Chemical Park by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry with Automatic Solid Phase Extraction

Residues of dexamethasone, prednisone, norethindrone, ethinylestradiol, methyltestosterone and mifepristone in surface water around medical and chemical park by ultra-high performance liquid chromatography-tandem mass spectrometry with automatic solid phase extraction (SPE). Surface water sample around medical and chemical park was randomly collected, and impurities in which were removed. The solution obtained was placed in a brown jar, and its acidity was adjust to pH 7. An aliquot (500 mL) of the water sample was passed through HLB SPE column activated beforehand at flow rate of 10 mL·min^-1, and the column was eluted with 15 mL of 20% (volume fraction) methanol solution. The eluate was collected and blown to nearly dry by nitrogen at 50 ℃, and the residue was redissolved and diluted to 1 mL with methanol. After mixing by vortex for 30 s, the mixed solution was analyzed by the optimized instrument working conditions. Agilent Zorbax Eclipse Plus C₁₈ column was used as the stationary phase, and the mixed solutions composed of 1 mmol·L^-1 ammonium acetate solution and acetonitrile at different volume ratios were used as mobile phase for gradient elution. The separated targets were detected by triple quadrupole tandem mass spectrometer in electrospray ion source negative ion mode and multiple reaction monitoring mode, and quantified by external standard method. It was shown that linear relationships between values of the peak area and the mass concentration of the 6 targets were kept in the same range of 0.005-5 mg·L^-1, with detection limits (3S/N) of 0.24, 0.14, 0.51, 0.16, 0.21, 0.08 μg·L^-1, respectively. Test for the spiked recovery was made on actual samples at the 3 concentration levels, giving recoveries of the 6 targets in the range of 83.9%-105%, with RSDs (n=5) of the determined values ranged from 2.7% to 4.1%, and dexamethasone and ethinylestradiol were detected at 0.75, 1.27 μg·L^-1 in the sample, respectively.