In-house validation of a liquid chromatography–tandem mass spectrometry method for the determination of selective androgen receptor modulators (SARMS) in bovine urine

Ambient ionization mass spectrometry provides screening of selective androgen receptor modulators

Ambient ionization mass spectrometry allows for analysis of samples in their natural state, i.e., with no sample pre-treatment. It can be viewed as a fast, simple, and economical analysis, but its main disadvantages include a lower analytical performance due to the presence of complex sample matrix and the lack of chromatographic separation prior to the introduction of the sample into the mass spectrometer. Here we present an application of two ambient ionization mass spectrometry techniques, i.e., Desorption Atmospheric Pressure Photoionization and Dielectric Barrier Discharge Ionization, for the analysis of known Selective Androgen Receptor Modulators, which represent common compounds of abuse in professional and semiprofessional sport. Eight real samples of illegal food supplements, seized by the local law enforcement, were used to test the performance of the ambient mass spectrometry and the results were validated against a newly developed targeted LC-UV-MS/MS method performed in multiple reaction monitoring mode with an external calibration for each analyte. In order to decide whether or not the compound can be declared as present, we proposed a system of rules for the interpretation of the obtained spectra. The criteria are based on mass spectrum matching (5-10 ppm accuracy from the theoretical exact mass and a correct isotopic pattern), duration of the mass signal (three or five consecutive scans, depending on the instrumentation used), and intensity above the background noise (threefold increase in intensity and absolute intensity above 5E4 or 1E5, depending on the instrumentation). When applying these criteria, good agreement was found between the tested methods. Ambient ionization techniques were effective at detecting SARMs at pharmacologically relevant doses, i.e., approximately above 1 mg per capsule, although they may fail to detect lower levels or isomeric species. It is demonstrated that when adhering to a set of clear and consistent rules, ambient mass spectrometry can be employed as a qualitative technique for the screening of illegal SARMs with sufficient confidence and without the necessity to perform a regular LC-MS analysis.

Investigation of stability of selective androgen receptor modulators in urine

Selective androgen receptor modulators (SARMs) are a class of new emerging "designer" steroid compounds gaining popularity over more well established anabolic-androgenic steroids (AAS) amongst both non-professional and elite athletes. Moreover, due to their anabolic activity, SARM compounds may also potentially be abused in livestock animals to increase meat production. Consequently, SARM residues should be monitored as a part of routine testing employed within both anti-doping and drug residue laboratories. Since only a limited amount of information on SARM compound stability is currently available within the peer-reviewed literature, this study reports a practical approach to assess optimal storage conditions for 15 SARM compounds in solvent solutions (standard stock and intermediate mixed standard solutions) stored at -20°C for up to 1 year, as well as in a range of urine test matrices (bovine, equine, canine and human) under frozen (-20°C, -80°C) storage for up to 20 weeks and post freeze-thaw cycles. Moreover, SARM storage stability within solvent extracts was assessed at -20°C (0-4 weeks) and 4°C (0-2 weeks). Findings demonstrate that SARM analytes are stable in reference solutions when stored at -20°C, apart from PF-06260414 (stock solution) which should be stored at lower temperatures (e.g. -80°C). A limited degree of compound instability was observed for a number of SARM analytes in urine both when stored at -20°C, and after repeated freeze-thaw cycles. Moreover, SARM compounds within reconstituted urine solvent extracts were found to be effectively stable when stored for up to 4 weeks at -20°C and for 2 weeks at 4°C. The long-term stability testing data reported here will inform the more timely and effective development and validation of analytical methods for SARM residue detection and analysis, ensuring confidence in findings from monitoring of livestock animals and anti-doping processes.

Monitoring of selective androgen receptor modulators in bovine muscle tissue by ultra-high performance liquid chromatography-tandem mass spectrometry

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First UHPLC-MS/MS assay for screening of 15 emerging SARMs in muscle tissue.

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Method fully validated according to relevant EU food control legislation.

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Analyte detection capability (CCβ) determined in the range of 0.5–5 ng g⁻¹.

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Assay amenable for use within routine residue control programmes.

Selective androgen receptor modulators (SARMs) are non-steroidal compounds widely reported as drugs of abuse in human and animal sports, with potential for misuse as growth promoters in animal-based food production. In this study, a first analytical methodology to simultaneous screen for a panel of emerging SARMs in bovine muscle was developed, validated (CCβ values from 0.5–5 ng g⁻¹), and applied to detect 15 structurally diverse compounds from nine SARM families. Muscle samples (200 mg) were homogenised in extraction solvent (MeCN:H₂O, 4:1, v/v) before clean-up (end-capped C₁₈ dSPE), defatting (n-hexane pre-saturated with MeCN partitioning) and concentration prior to UHPLC-MS/MS analysis. In the absence of incurred bovine muscle, method applicability was demonstrated by the analysis of rodent muscle tissue. The developed screening assay serves as a rapid, simple and cost-effective tool for surveillance monitoring of SARM abuse in livestock production systems as a pre-emptive measure ensuring food safety.

Quantitative analysis of cefquinome considering different matrix compositions of bovine colostrum and raw milk

A robust liquid chromatography-tandem mass spectrometry method was developed and comprehensively validated for the quantification of cefquinome considering the changing matrix composition from bovine colostrum to raw milk. Sample preparation consisted of addition of isotopically labeled cefquinome internal standard prior to protein precipitation of 2 g colostrum or milk followed by solid-phase extraction. A wide concentration range from 1 to 5000 ng cefquinome per gram of colostrum or milk was quantified using a 3200 QTRAP tandem mass spectrometer in positive ionization mode with electrospray ionization. Validation was performed according to the European Commission Decision 2002/657/EC guidelines. Matrix-comprehensive in-house validation included analytical limits CC_α and CC_β, recovery, precision and calibration curves with prediction intervals, storage conditions, and evaluation of robustness based on factorial effect analysis. The detection limit was 0.2 ng cefquinome per gram of colostrum or milk. Recovery was between 98.4 and 99.4% for cefquinome concentrations from 4 to 240 ng/g. None of the investigated validation factors (matrix, storage of extracts, lot of SPE cartridges, and operators) exerted an influence higher than ± 3.2%, indicating that these factors make relatively low contributions to the respective combined measurement uncertainties. The comprehensively validated method enables routine residue control purposes and to monitor the pharmacokinetics of cefquinome in bovine colostrum and raw milk. In particular, residue depletion curves of cefquinome from high concentrations in first milking after treatment to concentrations far below the maximum residue limit can be measured.