instrumental techniques applied to mineralogy and geochemistry

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100 Clemente Recio relatively simple procedure, consisting in separating two or three functional groups by LC; removing the pregnane metabolites by oxidation, and derivatising the steroids by acetylation. Only one chromatographic separation removes up to 75% of the unwanted steroids from the urine. The oxidation removes the majority of the complex side chains from the 17-hydroxypregnane steroid resulting in a cleaner sample for a simpler chromatogram. The derivatised samples are dissolved on cyclohexane and injected into the GC-C-IRMS, where they are analysed for their isotopic ratios. -24 -25 Pregnanediol -26 13 C PDB , ‰ -27 -28 5-Androstane-3 ,17-diol -29 5 -Androstane-3 ,17-diol -30 Synthetic Testosterone -31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Day of Test FIGURE 7. Evolution of the 13 C value of 5- and 5-androstane-3,17 diols and pregnanediol after administration of testosterone at the end of day 2. Data from Shackleton et al. (1997) and Phillips (1999). Experimental results (Fig. 7) show that 13 C of pregnanediol does not change dramatically by administration of testosterone, while 13 C of the 5- and 5-androstane- 3,17 diols become lighter after the administration, and only starts to recover after 6-7
Alike as two water drops: distinguishing one source of the same substance from another 101 days. The pregnanediol could be monitored as an internal reference to relate to diet, or can possibly be used to develop an indication ratio for abuse. Metabolites that are unaffected by testosterone could be used as the individual's baseline, and therefore regulatory values could be agreed upon for future doping tests. This technique could also be applied to the testing of other anabolic reagents, such as DHT, DHEA and epitestosterone. Cawley et al. (2004) found that 3,5-cyclo-5androstan-6-ol-17-one (“3,5-cyclo”) is a natural byproduct of metabolism of dehydroepiandrosterone (DHEA), but whose concentrations are elevated (5-15 times) following DHEA administration. By considering average values from available databases, it was proposed that any sample with 3,5-cyclo 140 ng/ml be tested by IRMS for significant 13 C depletion, since it was confirmed experimentally that 13 C of 3,5-cyclo change from –24.3‰ to –31.1‰ 9 hrs after administration of a single dose of DHEA, returning to baseline after 48 hrs. In case of continued administration of DHEA, 13 C 3,5-cyclo reached even lower values at –33.9‰. Nandrolone Evidence is emerging that exercise and legal supplements may raise endogenous 19-norandrostereone (19Na) above 2 ng per ml of urine, the current IOC threshold for reporting a doping offence. As a result, a preliminary study was undertaken by Phillips et al. (2000) to establish the feasibility of using stable isotope ratio mass spectrometry (IRMS) to distinguish between high endogenous urinary excretion and high excretion due to administration of a nandrolone doping agent. Six volunteers (3 male and 3 female) provided a single urine sample prior to steroid administration. The 13 C/ 12 C isotopic ratio of urinary pregnanediol (PD) and 19- norandrostereone (19Na) were then determined in a similar analytical manner to that described in Shackleton et al. (1997.a, b). The volunteers then self-administered 100 mg of 19-norandrostanedione, a legal “over the counter” food supplement. A second urine sample was taken 48 hours following administration and the 13 C/ 12 C isotopic ratio of urinary PD and 19Na was determined. Prior to steroid administration the 13 C value of PD (a nandrolone precursor) and 19Na (a nandrolone metabolite) were approximately equal (Fig. 8, top). 48 hours
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SEMINARIOS DE LA SOCIEDAD ESPAÑOLA
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FOREWORD On the occasion of the Spa
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INDEX Electron back-scattered diffr
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8 Elisabetta Mariani et al Introduc
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10 Elisabetta Mariani et al success
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14 Elisabetta Mariani et al FIGURE
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16 Elisabetta Mariani et al FIGURE
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18 Elisabetta Mariani et al In-situ
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TEM in Geology. Basics and applicat
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X-ray Absorption Spectroscopy in Mi
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