Introduction to the application of capillary gas chromatography of performance-enhancing drugs in doping control

Single-step transesterification with simultaneous concentration and stable isotope analysis of fatty acid methyl esters by gas chromatography-combustion-isotope ratio mass spectrometry

Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is increasingly applied to food and metabolic studies for stable isotope analysis (δ(13) C), with the quantification of analyte concentration often obtained via a second alternative method. We describe a rapid direct transesterification of triacylglycerides (TAGs) for fatty acid methyl ester (FAME) analysis by GC-C-IRMS demonstrating robust simultaneous quantification of amount of analyte (mean r(2) =0.99, accuracy ±2% for 37 FAMEs) and δ(13) C (±0.13‰) in a single analytical run. The maximum FAME yield and optimal δ(13) C values are obtained by derivatizing with 10% (v/v) acetyl chloride in methanol for 1 h, while lower levels of acetyl chloride and shorter reaction times skewed the δ(13) C values by as much as 0.80‰. A Bland-Altman evaluation of the GC-C-IRMS measurements resulted in excellent agreement for pure oils (±0.08‰) and oils extracted from French fries (±0.49‰), demonstrating reliable simultaneous quantification of FAME concentration and δ(13) C values. Thus, we conclude that for studies requiring both the quantification of analyte and δ(13) C data, such as authentication or metabolic flux studies, GC-C-IRMS can be used as the sole analytical method.

The abuse of diuretics as performance-enhancing drugs and masking agents in sport doping: pharmacology, toxicology and analysis

Diuretics are drugs that increase the rate of urine flow and sodium excretion to adjust the volume and composition of body fluids. There are several major categories of this drug class and the compounds vary greatly in structure, physicochemical properties, effects on urinary composition and renal haemodynamics, and site and mechanism of action. Diuretics are often abused by athletes to excrete water for rapid weight loss and to mask the presence of other banned substances. Because of their abuse by athletes, diuretics have been included on The World Anti-Doping Agency's (WADA) list of prohibited substances; the use of diuretics is banned both in competition and out of competition and diuretics are routinely screened for by anti-doping laboratories. This review provides an overview of the pharmacology and toxicology of diuretics and discusses their application in sports. The most common analytical strategies currently followed by the anti-doping laboratories accredited by the WADA are discussed along with the challenges laboratories face for the analysis of this diverse class of drugs.

Fast gas chromatographic/mass spectrometric determination of diuretics and masking agents in human urine

An analytical procedure was developed for the fast screening of 16 diuretics (acetazolamide, althiazide, amiloride, bendroflumethiazide, bumetanide, canrenoic acid, chlorthalidone, chlorthiazide, clopamide, ethacrynic acid, furosemide, hydrochlorthiazide, hydroflumethiazide, indapamide, triamterene, trichlormethiazide) and a masking agent (probenecid) in human urine. The whole method involves three analytical steps, including (1) liquid/liquid extraction of the analytes from the matrix, (2) their reaction with methyl iodide at 70 degrees C for 2 h to form methyl derivatives, (3) analysis of the resulting mixture by fast gas chromatography/electron impact mass spectrometry (fast GC/EI-MS). The analytical method was validated by determining selectivity, linearity, accuracy, intra and inter assay precision, extraction efficiencies and signal to noise ratio (S/N) at the lowest calibration level (LCL) for all candidate analytes. The analytical performances of three extraction procedures and five combination of derivatization parameters were compared in order to probe the conditions for speeding up the sample preparation step. Limits of detection (LOD) were evaluated in both EI-MS and ECNI-MS (electron capture negative ionization mass spectrometry) modes, indicating better sensitivity for most of the analytes using the latter ionization technique. The use of short columns and high carrier gas velocity in fast GC/MS produced efficient separation of the analytes in less than 4 min, resulting in a drastic reduction of the analysis time, while a resolution comparable to that obtained from classic GC conditions is maintained. Fast quadrupole MS electronics allows high scan rates and effective data acquisition both in scan and selected ion monitoring modes.

Gas-phase behaviour of negative ions produced from thiazidic diuretics under electrospray conditions

A systematic mass spectrometric study of 10 thiazidic diuretics and related compounds was undertaken by mass spectrometry (MS) with electrospray ionization in the negative ion mode. Collisional dissociation 'in-source' (CID-MS) and in a low-pressure collision cell (CID-MS/MS) were compared in both excitation regions. Spectra obtained by CID-MS and by CID-MS/MS were matched. Using the two methods, loss of HCl and consecutive dissociations from 2HCl losses were exhibited from compounds such as methyclothiazide and trichlormethiazide but not from other thiazidic diuretics that contain chlorine substituents in the aromatic moiety. However, deprotonated dichlorphenamide gave rise to loss of HCl by CID-MS and CID-MS/MS. For other diuretics such as hydroflumethiazide and hydrochlorothiazide, the loss of HCN and [HCN + SO(2)] was relevant. Reaction mechanisms were checked by means of deuterium-hydrogen exchange, which showed that deprotonation took place regioselectively on the heterocyclic moiety. The cleavage pathways require molecular isomerization forming ion-dipole complexes prior to decompositions, allowing long-distance proton transfer for neutral elimination. Identifications of the most specific fragmentations presented in this paper were applied to the screening and unambiguous identification of diuretics for horse doping control.

Role of gas chromatography-mass spectrometry with negative ion chemical ionization in clinical and forensic toxicology, doping control, and biomonitoring

This paper reviews procedures for the detection or quantification of drugs, pesticides, pollutants, and/or their metabolites relevant to clinical and forensic toxicology, doping control, or biomonitoring using gas chromatography-mass spectrometry with negative ion chemical ionization (GC-MS-NICI). Papers written in English between 1995 and 2000 are reviewed. Procedures are included for the analysis of the following halogen-containing or derivatizable compounds in common biosamples, such as whole blood, plasma, or urine, and in alternative matrices such as sweat, hair, bone, or muscle samples of humans or rats: benzodiazepines, cannabinoids, opioids, acetylsalicylic acid, angiotensin-converting enzyme inhibitors, ketoprofen, methylphenidate enantiomers, tegafur, zacopride, anabolic steroids, chlorophenols, chlorpyrifos, hexachlorocyclohexanes, organochlorines, and polychlorinated biphenyls. The principal information on each procedure is summarized in three tables to facilitate the selection of a method suitable for a specific analytic problem.