Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Drug Test Anal ; 4(12): 928-33, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22544546

RESUMO

An accurate method for the measurement of carbon isotope ratios of steroids in human urine has been developed at the National Measurement Institute, Australia (NMIA) for the certification of a freeze-dried human urine reference material (CRM NMIA MX005). The method measures δ(13)C values by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) analysis following hydrolysis, solvent extraction and high performance liquid chromatography (HPLC) purification. Reference δ(13)C values for testosterone metabolites etiocholanolone, androsterone, and endogenous reference compounds (ERCs) 11ß-hydroxyandrosterone and pregnanediol were determined, as well as information δ(13)C values for testosterone, epitestosterone, 11-oxoetiocholanolone, and a range of differences (Δ(13)C) between testosterone metabolites and ERCs. The measurement uncertainty was rigorously evaluated with expanded uncertainties for the reference δ(13)C values between 1.1 and 1.6 ‰ at the 95% coverage level.


Assuntos
Anabolizantes/urina , Isótopos de Carbono/urina , Certificação/normas , Dopagem Esportivo , Liofilização/normas , Cromatografia Gasosa-Espectrometria de Massas/normas , Substâncias para Melhoria do Desempenho/urina , Detecção do Abuso de Substâncias/normas , Testosterona/urina , Androsterona/análogos & derivados , Androsterona/urina , Austrália , Biomarcadores/urina , Biotransformação , Calibragem , Cromatografia Líquida de Alta Pressão , Etiocolanolona/urina , Humanos , Hidrólise , Valor Preditivo dos Testes , Pregnanodiol/urina , Controle de Qualidade , Padrões de Referência , Reprodutibilidade dos Testes , Solventes/química , Detecção do Abuso de Substâncias/métodos , Incerteza
2.
Rapid Commun Mass Spectrom ; 25(11): 1641-51, 2011 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-21594940

RESUMO

An alternative calibration procedure for use when performing carbon isotope ratio measurements by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) has been developed. This calibration procedure does not rely on the corrections in-built in the instrument software, as the carbon isotope ratios of a sample are calculated from the measured raw peak areas. The method was developed for the certification of a urine reference material for sports drug testing, as the estimation of measurement uncertainty is greatly simplified. To ensure that the method is free from bias arising from the choice of calibration material and instrument, the carbon isotope ratios of steroids in urine extracts were measured using two different instruments in different laboratories, and three different reference materials (CU/USADA steroid standards from Brenna Laboratory, Cornell University; NIST RM8539 mineral oil; methane calibrated against NIST RM8560 natural gas). The measurements were performed at LGC and the Australian National Measurement Institute (NMI). It was found that there was no significant difference in measurement results when different instruments and reference materials were used to measure the carbon isotope ratio of the major testosterone metabolites androsterone and etiocholanolone, or the endogenous reference compounds pregnanediol, 11- ketoetiocholanolone and 11ß-hydroxyandrosterone. Expanded measurement uncertainties at the 95% coverage probability ranged from 0.21‰ to 1.4‰, depending on analyte, instrument and reference material. The measurement results of this comparison were used to estimate a measurement uncertainty of δ(13)C for the certification of the urine reference material being performed on a single instrument using a single reference material at NMI.


Assuntos
Androstenóis/urina , Isótopos de Carbono/análise , Dopagem Esportivo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Pregnanodiol/urina , Testosterona/análogos & derivados , Testosterona/urina , Calibragem , Liofilização , Cromatografia Gasosa-Espectrometria de Massas/normas , Humanos , Padrões de Referência
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA