Quantification of urinary steroids by supported liquid extraction with GC-MS/MS: Unravelling cyclic fluctuations of...

A method for simultaneous quantification of urinary steroids has been developed using supported liquid extraction technique in combination with gas chromatography-triple quadruple tandem mass spectrometry. The supported liquid extraction technique could enrich low-concentration analytes by reducing matrix interference, hence the technique offered better extraction efficiency compared to conventional preparation methods. The method was shown to be linear (r² > 0.99) in the range of concentrations for all steroids with accuracy ranging from 88.0% to 115.6%. The intra- and inter-day precision, expressed as relative standard deviation, were both below 11.9%. The lower limits of quantification were between 1 and 50 ng·mL^-1, and the limits of detection were between 0.5 and 2.5 ng·mL^-1, which were suitable for the detection of steroids. The validated method was subsequently applied for analyzing urinary steroid profiling in regular menstrual cycle. The cyclic fluctuations and positive correlations between the steroids in different phases were observed. The results indicated that the proposed method was an effective tool for revealing hormonal fluctuations during menstrual cycle in complex biological samples.