Advances in structure elucidation of small molecules using mass spectrometry

The structural elucidation of small molecules using mass spectrometry plays an important role in modern life sciences and bioanalytical approaches. This review covers different soft and hard ionization techniques and figures of merit for modern mass spectrometers, such as mass resolving power, mass accuracy, isotopic abundance accuracy, accurate mass multiple-stage MS(n) capability, as well as hybrid mass spectrometric and orthogonal chromatographic approaches. The latter part discusses mass spectral data handling strategies, which includes background and noise subtraction, adduct formation and detection, charge state determination, accurate mass measurements, elemental composition determinations, and complex data-dependent setups with ion maps and ion trees. The importance of mass spectral library search algorithms for tandem mass spectra and multiple-stage MS(n) mass spectra as well as mass spectral tree libraries that combine multiple-stage mass spectra are outlined. The successive chapter discusses mass spectral fragmentation pathways, biotransformation reactions and drug metabolism studies, the mass spectral simulation and generation of in silico mass spectra, expert systems for mass spectral interpretation, and the use of computational chemistry to explain gas-phase phenomena. A single chapter discusses data handling for hyphenated approaches including mass spectral deconvolution for clean mass spectra, cheminformatics approaches and structure retention relationships, and retention index predictions for gas and liquid chromatography. The last section reviews the current state of electronic data sharing of mass spectra and discusses the importance of software development for the advancement of structure elucidation of small molecules

Discrimination of tetryl samples by gas chromatography – Isotope ratio mass spectrometry

Forensic profiling methods are critical to associate materials found in a crime scene with materials retrieved from a suspect. Isotope ratio mass spectrometry provides opportunity for possible differentiation among samples originating from different sources and has been engaged to solve forensic cases via discrimination not achievable with traditional techniques. Although it has been proven a useful tool in forensic cases its use is still limited. A preliminary evaluation of the IRMS technique towards the measurement of carbon isotope values in tetryl samples has been performed in the present study. Six samples of the explosive tetryl were analyzed using gas chromatography coupled with isotope ratio mass spectrometry and full discrimination among samples was achieved by measuring only carbon isotope ratios (13C/12C). © 201

Challenges in detecting substances for equine anti-doping

The artificial increase of the physical capability of horses using drugs is well known in racing and other equine sports. Both illicit and therapeutic substances are regarded as prohibited substances in competition in most countries. Some countries make distinctions for a few, specific drugs which are, however, allowed for use in other countries. The primary objective in the case of doping control is the detection of any trace of drug exposure, either parent drug or any of its metabolites, using the most powerful analytical methods which are generally based on chromatographic/mass spectrometric techniques. Of major concern in horseracing is the absence of a single organization regulating the anti-doping framework; instead of this, individual racing authorities provide rules and regulations often resulting in variations in the applied doping control programmes of different countries. The aim of this paper is to review the recent literature (approximately from 2012 to mid-2016) to highlight the numerous and diverse challenges faced in doping control of racing and equestrian sports, including the detection of designer drugs (anabolic steroids or stimulants) and of other emerging prohibited substances, such as peptides and noble gases in horse urine and plasma. Moreover, the application of ‘omics’ techniques (especially of metabolomics) deserves attention for establishing possible fingerprints of drug abuse as well as the evolution of instrumental analysis resulting a powerful ally in the fight against doping in equine sports. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd

Human in vivo metabolism study of LGD-4033

Selective androgen receptor modulators (SARMs) are an emerging class of therapeutics targeted to cachexia, sarcopenia, and hypogonadism treatment. LGD-4033 is a SARM which has been included on the Prohibited List annually released by the World Anti-Doping Agency (WADA). The aim of the present work was the investigation of the metabolism of LGD-4033 in a human excretion study after administration of an LGD-4033 supplement, the determination of the metabolites' excretion profiles with special interest in the determination of its long-term metabolites, and the comparison of the excretion time of the phase I and phase II metabolites. The results were also compared to those derived from previous LGD-4033 studies concerning both in vitro and in vivo experiments. Supplement containing LGD-4033 was administered to one human male volunteer and urine samples were collected up to almost 21 days. Analysis of the hydrolyzed (with β-glucuronidase) as well as of the non-hydrolyzed samples was performed using liquid chromatography–high resolution mass spectrometry (LC–HRMS) in negative ionization mode and revealed that, in both cases, the two isomers of the dihydroxylated metabolite (M5) were preferred target metabolites. The gluco-conjugated parent LGD-4033 and its gluco-conjugated metabolites M1 and M2 can be also considered as useful target analytes in non-hydrolyzed samples. The study also presents two trihydroxylated metabolites (M6) identified for the first time in human urine; one of them was recently reported in an LGD-4033 metabolism study in horse urine and plasma. © 2018 John Wiley & Sons, Ltd

Determination of salmeterol, α-hydroxysalmeterol and fluticasone propionate in human urine and plasma for doping control using UHPLC–QTOF–MS

Salmeterol and fluticasone are included in the Prohibited List annually issued by the World Anti-Doping Agency. While for other permitted beta-2 agonists a threshold has been established, above which any finding constitutes an Adverse Analytical Finding, this is not the case with salmeterol. The salmeterol metabolite, α-hydroxysalmeterol, has been described as a potentially more suitable biomarker for the misuse of inhaled salmeterol. In this study, a new and rapid UHPLC–QTOF–MS method was developed and validated for the simultaneous quantification of salmeterol, α-hydroxysalmeterol and fluticasone in human urine and plasma, which can be used for doping control. The analytes of interest were extracted by means of solid phase extraction and were separated on a Zorbax Eclipse Plus C18 column. Detection was performed in a quadrupole time-of-flight mass spectrometer equipped with an electrospray ionization source, in positive mode for the detection of salmeterol and its metabolite and in negative mode for the detection of fluticasone. Method was validated over a linear range from 0.10 to 2.00 ng/ml for salmeterol and fluticasone, and from 1.00 to 20.0 ng/ml for α-hydroxysalmeterol, in urine, whereas in plasma, the linear range was from 0.025 to 0.500 ng/ml for salmeterol and fluticasone, respectively. © 2021 John Wiley & Sons, Ltd

Determination of anabolic androgenic steroids as imidazole carbamate derivatives in human urine using liquid chromatography–tandem mass spectrometry

Anabolic androgenic steroids are widely abused substances in sports doping. Their detection present limitations regarding the use of soft ion sources such as electrospray or atmospheric pressure chemical ionization by liquid chromatography–tandem mass spectrometry. In the current study, a novel derivatization method was developed for the ionization enhancement of selected anabolic androgenic steroids. The proposed method aims at the introduction of an easily ionizable moiety into the steroid molecule by converting the hydroxyl groups into imidazole carbamates using 1,1′-carbonyldiimidazole as derivatization reagent. The proposed method was applied to water and urine samples spiked with exogenous anabolic androgenic steroids in various concentration levels. Steroid imidazole carbamate derivatives have shown intensive [M+H]+ signals under electrospray ionization and common fragmentation patterns in tandem mass spectrometry mode with [M-CO2+H]+ and [M-ΙmCO2+H]+ as major ions with low collision energy. The obtained results showed that the majority of steroids were detectable at concentrations equal or lower to their minimum required performance level according to the World Anti-Doping Agency technical document. The proposed method is sensitive with a preparation procedure that could be easily applied to the analysis of doping control samples. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Gas chromatographic - Mass spectrometric cardiotonic glycosides detection in equine urine doping analysis

A screening method for the detection of cardiotonic glycosides in horse's urine is presented in this paper. This method is based on the detection by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-high resolution mass spectrometry (GC-HRMS) of the trimethylsilyl (TMS) derivatives of the aglycon moieties of these compounds after solid phase extraction and methanolysis, according to the standard procedure currently used for the screening of anabolic steroids in horses, in the Athens Doping Control Laboratory. This validated method was also applied for the excretion study of digoxin in two mare horses after a single administration of a 75 mug Kg(-1) oral dose, by GC-MS and GC-HRMS