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Objective To develop a candidate reference method for the measurement of progesterone in human serum.Methods The serum sample is mixed with the internal standard [3,4-~(13)C_2] progesterone.After extraction with n-hexane and purified by a aqueous solution of 2-Hydroxypropyl-?- cyclodextrin (HP-?-CD),the serum progesterone and labeled progesterone are converted to the 3-enol heptafluorobutyrate and analyzed by gas chromatography mass spectrometry (GC/MS) with selected ion monitoring.The concentration of serum progesterone is calculated by bracketing method.Results The results gave coefficients of variation (CVs) of 0.69% to 2.12%.The analytical recoveries ranged from 98.3% to 100.1%.The results of measuring certified reference materials of serum progesterone are agree with the target value.Conclusion The procedure for measuring progesterone in serum is a highly accurate and precise method and may be used as a candidate reference method for serum progesterone assays.
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OBJECTIVE:To study the influence of both pH and complexation by hydroxypropyl-?-cyclodextrin(HPCD) on the overall solubility of hydroxycamptothecin(HCPT) with particular focus on the equilibrium between its lactone-and carboxylate-form.METHODS:Phase solubility studies at pH values and physiologically acceptable HPCD concentrations were performed,and the amounts of solubilized HCPT quantified by HPLC.The lactone-carboxylate-ratios from the equilibrium were studied.RESULTS:The solubility of HCPT increased with both increasing pH and HPCD concentration.The apparent complexation constant decreased with increasing pH.The lactone-carboxylate equivalence point shifted from a pH value of 6.5,7.0 and 7.3 with 0%,10% and 25% HPCD,respectively.Separate complexation constants for the carboxylate-HCPT and lactone-HCPT could thus be derived.CONCLUSION:The solubilizing and stabilizing effects of HPCD on HCPT in aqueous solution were good.