Τίτλος:
External calibration in Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry measurements of endogenous androgenic anabolic steroids in sports doping control
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
An alternative calibration procedure for the Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS) measurements of the World Antidoping Agency (WADA) Accredited Laboratories is presented. To alleviate the need for externally calibrated CO2 gas for GC-C-IRMS analysis of urinary steroid metabolites, calibration using an external standard mixture solution of steroids with certified isotopic composition was investigated. The reference steroids of the calibration mixture and routine samples underwent identical instrumental processes. The calibration standards bracketed the entire range of the relevant δ13C values for the endogenous and exogenous steroids as well as their chromatographic retention times. The certified δ13C values of the reference calibrators were plotted in relation to measured m/z 13CO2/12CO2 (i.e. R(45/44)) mass spectrometric signals of each calibrator. δ13C values of the sample steroids were calculated from the least squares fit through the calibration curve. The effect of the external calibration on δ13C values, using the same calibration standards and set of urine samples but different brands of GC-C-IRMS instruments, was assessed by an interlaboratory study in the WADA Accredited Laboratories of Sydney, Australia and Athens, Greece. Relative correspondence between the laboratories for determination of androsterone, etiocholanolone, 5β-androstane-3α,17β-diacetate, and pregnanediacetate means were SD(δ13C)=0.12‰, 0.58‰, -0.34‰, and -0.40‰, respectively. These data demonstrate that accurate intralaboratory external calibration with certified steroids provided by United States Antidoping Agency (USADA) and without external CO2 calibration is feasible and directly applicable to the WADA Accredited Laboratories for the harmonization of the GC-C-IRMS measurements. © 2011 Elsevier B.V.
Συγγραφείς:
Kioussi, M.K.
Angelis, Y.S.
Cawley, A.T.
Koupparis, M.
Kazlauskas, R.
Brenna, J.T.
Georgakopoulos, C.G.
Περιοδικό:
Journal of Chromatography A
Λέξεις-κλειδιά:
Accredited laboratories; Androgenic anabolic steroids; Athens , Greece; Calibration curves; Calibration mixtures; Calibration procedure; Calibration standard; Chromatographic retention; Doping control; Endogenous steroids; Etiocholanolone; External calibration; Interlaboratory studies; Isotopic composition; Least squares fit; Mixture solution; Spectrometry measurements; Sydney , Australia; Urine sample; World Anti-Doping Agency, Calibration; Carbon dioxide; Combustion; Isotopes; Laboratories; Lipids; Mass spectrometry; Spectrometers; Standards, Gas chromatography, 5beta androstane 3alpha 17beta diacetate; androgen; androsterone; carbon dioxide; etiocholanolone; isotope; pregnanediacetate; unclassified drug, article; Australia; calibration; chromatography; diagnostic accuracy; doping; gas chromatography; gas chromatography combustion isotope ratio mass spectrometry; Greece; hormone determination; laboratory; mass spectrometry; priority journal; signal transduction; sport; steroid urine level; urinalysis, Anabolic Agents; Calibration; Carbon Isotopes; Doping in Sports; Gas Chromatography-Mass Spectrometry; Humans; Male; Steroids; Substance Abuse Detection
DOI:
10.1016/j.chroma.2011.06.014
