Code: 21A04RM
In the glucuronated fraction, the differences among Δδ13C pairs are known to reflect the metabolic isotopic fractionation and potential method bias. This is known as well, to be magnified in the sulfate fraction. After the publication of some results concerning the sulfate fraction analysis advantages, WADA TD2021IRMS states that Epiandrosterone could be used as an additional TC for GC-C-IRMS
analysis to determine the administration of testosterone or its precursors and the decision rule for IRMS positive test is based on the absolute Δδ13C value of ERC-EpiA pair higher than 4‰. No
specification is explicitly done about which ERC should be used to evaluate an analyte from the sulfate fraction and in which fraction the ERC should be present.
The project aims to study the differences between the δ13C and Δδ13C values obtained taking into consideration the ERC in glucuronated and sulfate fraction of urine, during the evaluation of
sulfated target compounds. It will be studied the classic ERCs: Pregnanediol, Pregnanetriol, 11β-hydroxy-androsterone,11β-hydroxy-etiocholanolone and Androstenol. Sulfoconjugation of these compounds is not extensively published but we do not expect more than 10% based on the structure. In this case, a preliminary and alternative study of estrogens will be carrying out as well as androst-5-ene-3β,17α-diol proposed previously.
If the goals of the proposed project are reached, we should be able to align the results based on ERC and TC both excreted as sulfo-conjugates. Besides, the bias should be minimized because the
already described difference between CIR of glucuronate and sulfate fractions could be avoided. Finally, we expected to increase the knowledge regarding the δ13C of ERCs and Δδ13C pairs, all in
sulfate fraction from the Reference Population Data (at least for males) which can contribute to the selection of a sensitive and/or affordable ERC for IRMS confirmation in sulfate fraction of the urine.