Determination of free and deconjugated testosterone and epitestosterone in urine using SPME and LC-MS/MS.
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Issue Date
2011-Jan
Authors
Zhan, Yanwei
Musteata, Florin M
Basset, Fabien A
Pawliszyn, Janusz
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Abstract
Background: A thin sheet of polydimethylsilosane membrane was used as an extraction phase for solid-phase microextraction. Compared with fiber or rod solid-phase microextraction geometries, the thin film exhibited much higher extraction capacity without sacrificing extraction time due to its higher area-to-volume ratio. The analytical method involved direct extraction of unconjugated testosterone (T) and epitestosterone (ET) followed by separation on a C18 column and detection by selected reaction monitoring in positive ionization mode.
Results: The limit of detection was 1 ng/l for both T and ET. After method validation, free (unconjugated) T and ET were extracted and quantified in real samples. Since T and ET are extensively metabolized, the proposed method was also applied to extract the steroids after enzymatic deconjugation of urinary-excreted steroid glucuronides.
Conclusion: The proposed method allows quantification of both conjugated and unconjugated steroids, and revealed that there was a change in the ratio of T to ET after enzymatic deconjugation, indicating different rates of metabolism.
Results: The limit of detection was 1 ng/l for both T and ET. After method validation, free (unconjugated) T and ET were extracted and quantified in real samples. Since T and ET are extensively metabolized, the proposed method was also applied to extract the steroids after enzymatic deconjugation of urinary-excreted steroid glucuronides.
Conclusion: The proposed method allows quantification of both conjugated and unconjugated steroids, and revealed that there was a change in the ratio of T to ET after enzymatic deconjugation, indicating different rates of metabolism.
Citation
Zhan Y, Musteata FM, Basset FA, Pawliszyn J. Determination of free and deconjugated testosterone and epitestosterone in urine using SPME and LC-MS/MS. Bioanalysis. 2011 Jan;3(1):23-30. doi: 10.4155/bio.10.177. PMID: 21175364.
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