Sample Pretreatment for Confirmation of 19 – Norsteroids by GC – C – IRMS in Doping Control
National Doping Control Centre, Mahidol University
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October 24, 2019Sample Pretreatment for Confirmation of 19 – Norsteroids by GC – C – IRMS in Doping Control
Figure 1 : IRMS chromatograms of 30 mL urine spiked at 2.5 ng/mL 19-NE (A), 19-NA (B) and pure standard 19-NE (C) and 19-NA (D).
Title :
Sample Pretreatment for Confirmation of 19 – Norsteroids by GC – C – IRMS in Doping Control
Researchers :
Nimsoongnern S., Weewong C., Lohwithee S., Wiriyakosol N., Wilairat P., Kongpatanakul S.
Confirmation of the use of 19-norsteroids requires the identification of the exogenous origin of the main metabolite, 19-norandrosterone (19-NA), when found in the urine at concentrations between 2.5 ng/mL and 15 ng/mL. An effective pretreatment procedure is necessary prior to the IRMS measurement. Two HPLC clean up steps were employed to isolate the fractions of 19-NA, 19-noretiocholanolone (19-NE) and two endogenous reference compounds (ERCs), pregnandiol (PD) and androsterone (Andro). Validation followed the WADA requirements as specified in TD2017NA and TD2016IRMS. Blank urine, 25-30 mL, spiked with 19-NA and 19-NE at 2.5-15 ng/mL, were validated for intra- and inter-assay precisions. The accuracy and fractionation were evaluated using standard 19-NA, 19-NE and certified standard USADA34-1 spiked in stripped urine. The results show no interference peak close to the target compounds. The difference between the 13C (‰) of pure certified standard and spiked stripped urine of less than 0.5 ‰ verified the accuracy of 13C measurement and non-fractionation effect of the sample preparation procedure. This method is fit for the determination of 13C (‰) of 19-NA and 19-NE for anti-doping purposes.
Publishing :
Recent Advances in Doping Analysis (25) Proceeding of the Manfred Donike Workshop 35th Cologne Workshop on Dope Analysis. 5th to 10th March 2017, page 136-139.
Key Contact Person :
Mrs.Morakot Kaewklum
National Doping Control Centre, Mahidol University
+66 2 354 7149 – 50