Validation of steroid sulfates deconjugation for metabolic studies. Application to human urine samples

Background: Urinary sulfate fraction of the anabolic androgenic steroids is not analyzed routinely in anti-doping analyses but has demonstrated in the last years an increasing interest among the anti-doping community. Sulfate conjugates are linked to plasma proteins increasing the residence time in the body compared to glucuroconjugated metabolites, and then their analyses may allow improving the detection time window of specific metabolites. Hydrolysis of sulfates can be made enzymatically or chemically and can be challenging, depending on the strategy selected. Methods: Hydrolysis by solvolysis was validated for metabolic studies, focusing on setting a quality control able to assess the hydrolytic step. To the internal standards mixture, androsterone-D4 and etiocholanolone-D5 sulfate were added. The proposed protocol was applied over samples collected after dehydroepiandrosterone (DHEA) administrations. Results: The stability of the structures showed good results, and no evident formation of degradation products was observed. Internal standard to monitor the efficiency of hydrolysis, recovery, and retention time was successfully introduced. Additional analytes (4 beta-hydroxy-DHEA, 5-androstene-3 beta,17 beta-diol and 5 alpha-androstane3 beta,17 beta-diol) were found to be affected besides of DHEA and epiandrosterone (epiA) as previously described. Conclusions: Results in terms of linearity, precision, and accuracy, showed that the method is suitable to quantify seven analytes in urine in the sulfated fraction. The validated method was successfully applied to urine samples after administration of DHEA to detect this compound in the sulfate fraction and preliminarily to negative samples from athletes of both sexes, to determine Q1 and Q3 inter-quartiles. A quality control assessment for the hydrolysis efficiency was established for every individual sample.