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Sample Pretreatment for Confirmation of 19 – Norsteroids by GC – C – IRMS in Doping Control

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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).

Sample Pretreatment for Confirmation of 19 – Norsteroids by GC – C – IRMS in Doping Control

National Doping Control Centre, Mahidol University

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.

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).

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