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Androgenic anabolic steroids (AAS) are prohibited in sports due to their anabolic effects. Doping control laboratories usually face the screening of AAS misuse by target methods based on MS detection. Although these methods allow for the sensitive and specific detection of targeted compounds and metabolites, the rest remain undetectable. This fact opens a door for cheaters, since different AAS can be synthesized in order to evade doping control tests. This situation was evidenced in 2003 with the discovery of the designer steroid tetrahydrogestrinone. One decade after this discovery, the detection of unknown AAS still remains one of the main analytical challenges in the doping control field. In this manuscript, the current situation in the detection of unknown AAS is reviewed. Although important steps have been made in order to minimize this analytical problem and different analytical strategies have been proposed, there are still some drawbacks related to each approach. Source


Ibanez M.,Jaume I University | Sancho J.V.,Jaume I University | Pozo O.J.,DoCoLab | Pozo O.J.,Bioanalysis research group | Hernandez F.,Jaume I University
Rapid Communications in Mass Spectrometry | Year: 2011

The herbicide bromacil has been extensively used in the Spanish Mediterranean region, and although plant protection products containing bromacil have been withdrawn by the European Union, this compound is still frequently detected in surface and ground water of this area. However, the fast and complete disappearance of this compound has been observed in water intended for human consumption, after it has been subjected to chlorination. There is a concern about the possible degradation products formed, since they might be present in drinking water and might be hazardous. In this work, the sensitive full-spectrum acquisition, high resolution and exact mass capabilities of hybrid quadrupole time-of-flight (QTOF) mass spectrometry have allowed the discovery and proposal of structures of transformation products (TPs) of bromacil in water subjected to chlorination. Different ground water samples spiked at 0.5 μg/mL were subjected to the conventional chlorination procedure applied to drinking waters, sampling 2-mL aliquots at different time intervals (1, 10 and 30 min). The corresponding non-spiked water was used as control sample in each experiment. Afterwards, 50 μL of the water was directly injected into an ultra-high-pressure liquid chromatography (UHPLC)/electrospray ionization (ESI)-(Q)TOF system. The QTOF instrument enabled the simultaneous recording of two acquisition functions at different collision energies (MS E approach): the low-energy (LE) function, fixed at 4 eV, and the high-energy (HE) function, with a collision energy ramp from 15 to 40 eV. This approach enables the simultaneous acquisition of both parent (deprotonated and protonated molecules) and fragment ions in a single injection. The low mass errors observed for the deprotonated and protonated molecules (detected in LE function) allowed the assignment of a highly probable molecular formula. Fragment ions and neutral losses were investigated in both LE and HE spectra to elucidate the structures of the TPs found. For those compounds that displayed poor fragmentation, product ion scan (MS/MS) experiments were also performed. On processing the data with specialized software (MetaboLynx), four bromacil TPs were detected and their structures were elucidated. To our knowledge, two of them had not previously been reported. © 2011 John Wiley & Sons, Ltd. Source


Marcos J.,University Pompeu Fabra | Pozo O.J.,Bioanalysis research group
Bioanalysis | Year: 2015

The determination of steroids in biological samples is essential in different areas of knowledge. MS combined with either GC or LC is considered the best analytical technique for specific and sensitive determinations. However, due to the physicochemical properties of some steroids, and the low concentrations found in biological samples, the formation of a derivative prior to their analysis is required. In GC-MS determinations, derivatization is needed for generating volatile and thermally stable compounds. The improvement in terms of stability and chromatographic retention are the main reasons for selecting the derivatization agent. On the other hand, derivatization is not compulsory in LC-MS analyses and the derivatization is typically used for improving the ionization and therefore the overall sensitivity achieved. © 2015 Future Science Ltd. Source


Marcos J.,University Pompeu Fabra | Pozo O.J.,Bioanalysis research group
Journal of Steroid Biochemistry and Molecular Biology | Year: 2015

The study of the metabolism of steroids has a long history; from the first characterizations of the major metabolites of steroidal hormones in the pre-chromatographic era, to the latest discoveries of new forms of excretions. The introduction of mass spectrometers coupled to gas chromatography at the end of the 1960's represented a major breakthrough for the elucidation of new metabolites. In the last two decades, this technique is being complemented by the use of liquid chromatography-mass spectrometry (LC-MS). In addition of becoming fundamental in clinical steroid determinations due to its excellent specificity, throughput and sensitivity, LC-MS has emerged as an exceptional tool for the discovery of new steroid metabolites.The aim of the present review is to provide an overview of the current LC-MS procedures used in the quest of novel metabolic products of steroidal hormones and exogenous steroids. Several aspects regarding LC separations are first outlined, followed by a description of the key processes that take place in the mass spectrometric analysis, i.e. the ionization of the steroids in the source and the fragmentation of the selected precursor ions in the collision cell. The different analyzers and approaches employed together with representative examples of each of them are described. Special emphasis is placed on triple quadrupole analyzers (LC-MS/MS), since they are the most commonly employed. Examples on the use of precursor ion scan, neutral loss scan and theoretical selected reaction monitoring strategies are also explained. © 2015 Elsevier Ltd. Source


Deventer K.,Ghent University | Pozo O.J.,Bioanalysis research group | Verstraete A.G.,Ghent University | Van Eenoo P.,Ghent University
TrAC - Trends in Analytical Chemistry | Year: 2014

In the past 20. years, liquid chromatography-mass spectrometry (LC-MS) has become a standard analytical technique in doping control and toxicology laboratories. Research groups have successfully applied it to detect substances by direct injection, or "dilute-and-shoot"-LC-MS (DS-LC-MS).However, some urinary components can precipitate into the vial, hampering the correct injection. Dissolved urinary matrix is responsible for shifted retention times and ion suppression or ion enhancement. To compensate for the effect of the matrix, an isotope-labeled internal standard (IL-ISTD) is the best choice.Dilution can also minimize the matrix effect, but can result in reduced analyte detectability. Hence, DS-LC-MS methods are predominantly available for substances for which the required urinary detection levels are high and that show good ionization efficiency.Taking into account the progressive increase in instrument sensitivity, we expect that the application of DS-LC-MS will also come available for substances with low required detection levels or limited ionization efficiency. © 2013 Elsevier Ltd. Source

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