Chromatographic techniques--the basis of doping control

Optimizing analytical precision in the identification of synthetic cathinones and isomers: a comparative assessment of diverse GC-MS operating parameters

Analyzing new psychoactive substances (NPSs) in forensic laboratories present a formidable challenge globally. Within illicit drug analysis, gas chromatography-mass spectrometry (GC-MS) emerges as a robust analytical tool. This study endeavors to assess and compare peak resolution in the analysis of illicit drugs, specifically focusing on 21 synthetic cathinones, encompassing 9 cathinone isomers. Varied GC-MS operating conditions, including distinct GC-MS columns and thermal gradients, were systematically employed for the simultaneous analysis of these synthetic cathinones. The study utilized HP-1 nonpolar and HP-5MS low-bleed columns to achieve optimal analyte resolution through modulation of GC-MS oven conditions. Mass spectra were meticulously recorded within a mass-to-charge (m/z) range spanning from 40 to 500 in full scan mode. The data showed that the cathinone isomers slightly differed in retention times and mass spectra. The GC oven conditions affected the peak resolution for chromatographic separation even with the same column. The peak resolution improved using a slower thermal gradient heat speed with a prolonged analysis time. Conclusively, the interplay of GC columns and thermal gradients emerged as pivotal factors impacting peak resolution in the analysis of illicit drugs. These empirical insights contribute to a nuanced understanding of peak resolution dynamics and facilitate the identification of synthetic cathinones, including their isomers, in seized materials through the judicious application of GC-MS methodologies.

Affinity-based biosensors in sport medicine and doping control analysis

Affinity-based biosensors (ABBs) have started to be considered in sport medicine and doping control analysis because they are cheap, easy to use and sufficiently selective analytical devices, characterized by a reversible interaction with the analyte under investigation allowing the use of the same sensor for multiple analyses. In this review we describe the main categories of substances reported in the World Anti-Doping Agency Prohibited List and how ABBs may contribute to their detection. Although several ABBs proposed in the last few years display limit of detections that are in principle matching the World Anti-Doping Agency requirements, their application in the framework of 'traditional' antidoping tests seems quite unlikely, mainly because of the still insufficient selectivity especially in the case of 'pseudo-endogenous' compounds, and on the lack of complete information regarding potential matrix effects in real samples and following their routine use. At the same time, ABBs could contribute to fill a significant information gap concerning complementary evidence that can be obtained from their use 'on the spot', as well as to preselect a risk population of individuals to be targeted for a full antidoping test; while in sport medicine they could contribute to obtaining analytical information of physiological relevance from the measurement of specific parameters or markers before, during and after physical exercise.

Analytical aspects in doping control: challenges and perspectives

Since the first anti-doping tests in the 1960s, the analytical aspects of the testing remain challenging. The evolution of the analytical process in doping control is discussed in this paper with a particular emphasis on separation techniques, such as gas chromatography and liquid chromatography. These approaches are improving in parallel with the requirements of increasing sensitivity and selectivity for detecting prohibited substances in biological samples from athletes. Moreover, fast analyses are mandatory to deal with the growing number of doping control samples and the short response time required during particular sport events. Recent developments in mass spectrometry and the expansion of accurate mass determination has improved anti-doping strategies with the possibility of using elemental composition and isotope patterns for structural identification. These techniques must be able to distinguish equivocally between negative and suspicious samples with no false-negative or false-positive results. Therefore, high degree of reliability must be reached for the identification of major metabolites corresponding to suspected analytes. Along with current trends in pharmaceutical industry the analysis of proteins and peptides remains an important issue in doping control. Sophisticated analytical tools are still mandatory to improve their distinction from endogenous analogs. Finally, indirect approaches will be discussed in the context of anti-doping, in which recent advances are aimed to examine the biological response of a doping agent in a holistic way.

Surface plasmon resonance in doping analysis

Doping analysis relies on the determination of prohibited substances that should not be present in the body of an athlete or that should be below a threshold value. In the case of xenobiotics their mere presence is sufficient to establish a doping offence. However, in the case of human biotics the analytical method faces the difficulty of distinguishing between endogenous and exogenous origin. For this purpose ingenious strategies have been implemented, often aided by state-of-the-art technological advancements such as mass spectrometry in all its possible forms. For larger molecules, i.e. protein hormones, the innate structural complexity, the heterogeneous nature, and the extremely low levels in biological fluids have rendered the analytical procedures heavily dependent of immunological approaches. Although approaches these confer specificity and sensitivity to the applications, most rely on the use of two, or even three, antibody incubations with the consequent increment in assay variability. Moreover, the requirement for different antibodies that separately recognise different epitopes in screening and confirmation assays further contributes to differences encountered in either measurement. The development of analytical techniques to measure interactions directly, such as atomic force microscopy, quartz crystal microbalance or surface plasmon resonance, have greatly contributed to the accurate evaluation of molecular interactions in all fields of biology, and expectations are that this will only increase. Here, an overview is provided of surface plasmon resonance, and its particular value in application to the field of doping analysis.

High-speed gas chromatography in doping control: Fast-GC and fast-GC/MS determination of β-adrenoceptor ligands and diuretics

In official doping controls, about 300 drugs and metabolites have to be screened for each sample. Moreover, the number of determinations to be routinely processed increases continuously as the number of both samples and potential illicit drugs keeps growing. As a consequence, increasingly specific, sensitive, and, above all, fast methods for doping controls are needed. The present study presents an efficient fast-GC/MS approach to the routine screening of two different classes of doping agents, namely beta-adrenoceptor ligands and diuretics (belonging to the S3, P2, and S5 groups of the WADA list of prohibited substances). Narrow bore columns (100 mm id) of different lengths and coated with apolar stationary phases were successfully used to separate the derivatized analytes; preliminary experiments (results not shown) showed better performances with OV-1701 for the separation of beta-adrenoceptor ligands. On the same stationary phase some diuretics required too high a temperature or a long isothermal time for elution, in which case a DB1-MS column was preferred. Two methods of sample preparation, derivatization, and analysis were used on aqueous standard mixtures of, respectively, (i) eight beta-adrenoceptor ligands, including five beta-antagonists (acebutolol, alprenolol, atenolol, metoprolol, pindolol) and three beta2-agonists (salbutamol, clenbuterol, terbutaline) and (ii) seventeen diuretic drugs (acetazolamide, althiazide, bendroflumethiazide, bumethanide, canrenone, chlorothiazide, chlortalidone, clopamide, ethacrinic acid, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, indomethacine, spironolactone, triamterene, trichloromethiazide) and one masking agent (probenecid). The mixture of beta-adrenoceptor ligand derivatives was efficiently separated in about 5.6 min, while the one of 18 diuretics and masking agents required less than 5 min for analysis. Limits of detection were from 1 microg/L for pindolol, ethacrinic acid, furosemide, indomethacine, and trichloromethiazide, to 20 microg/L for terbutaline, salbutamol, and metoprolol, and 50 microg/L for clopamide; the instrumental repeatability proved to be excellent (area RSD% <2 for almost all analytes). For this work a quadrupole MS with inert ion source has been used, demonstrating that the quadrupole technology is perfectly adequate to provide precise integration of 400 ms-wide GC peaks.

HPLC method development for testosterone propionate and cipionate in oil-based injectables

Two isocratic liquid chromatographic methods for the determination of testosterone propionate (TP) and cipionate (TC) in oil-based injectables using methyltestosterone and bolasterone as internal standards, respectively, have been developed and validated. Mobile phases 57% water:acetonitrile 43% (v:v) and 54% water:acetonitrile 46% (v:v) were used for TP and TC, respectively. For both methods, a bonded-silica Luna CN (250 mm x 4.6 mm i.d., 5 microm) (25 degrees C) column, a flow-rate 1 ml min(-1) and UV absorbance detection at 245 nm were used and two separations up to base line were achieved. Prior to HPLC analysis, sample preparation was required, including extraction of TP and TC from oil-based injectables using the surfactant sodium dodecyl sulphate.

Drug metabolism: in vitro biotransformation of anabolic steroids in canines

Forensic drug testing of anabolic steroids in racing animals is required because of the potential for steroid abuse. Often when the metabolic products of an administered compound have not been identified, the analysis and verification of the administered compound is difficult. The objective of this study was to qualitatively identify the in vitro phase I biotransformation products of anabolic steroids that have a high potential for abuse in canines. The investigated steroids included testosterone, methyltestosterone, mibolerone and boldenone. Steroid biotransformation products were generated using beagle liver microsomes and analysed by high performance liquid chromatography (HPLC)/mass spectrometry (MS) with an electrospray ionization source. Characterization of steroid metabolites was based on HPLC retention, UV and mass spectra. The major testosterone metabolites were identified as androstenedione and 6beta- and 16alpha-hydroxytestosterone. 6beta-Hydroxymethyltestosterone was identified as a major metabolite in the methyltestosterone microsomal incubations. Several mibolerone metabolites were identified as monohydroxylated mibolerones as well as an oxidized mibolerone metabolite. Boldenone metabolites were identified as monohydroxylated boldenones, oxidized boldenone, and testosterone. This information should assist in the determination of anabolic steroid use in canines through the correlation of the urinary metabolites to the administered drug.

Stimulants, narcotics and beta-blockers: 25 years of development in analytical techniques for doping control

More than 25 years of developing doping control methods have led to comprehensive screening and confirmation procedures for stimulants, narcotics and beta-blockers. Much of this work has been initiated and/or improved by the late Prof. Dr. Manfred Donike. The methodological approach covered in this overview was applied to doping control procedures during the XXV Summer Olympics in Barcelona, Spain, in 1992 and the XVII Winter Olympics in Lillehammer, Norway, in 1994. Urine samples are screened through a combination of two analytical methods that are complementary: (a) gas chromatographic analysis of the parent compound and unconjugated metabolites, following single-step sample extraction and detection by a nitrogen-specific detector based on a retention index identification system and (b) gas chromatographic analysis including also conjugated drugs and metabolites after hydrolysis, solid-phase extraction, derivatisation and mass spectrometric detection. Confirmation and identification is always performed by gas chromatographic separation and full scan mass spectrometric detection. These methods facilitate the rapid screening and confirmation of more than 100 stimulants, narcotic analgesics and beta-blockers in urine for at least 24 h after the intake of a pharmaceutical dose. Application of the methods ensures high quality standards for the unequivocal identification of doping agents as well as a rapid turnaround time for sample analyses.