Comprehensive IM-MS approach for SARMs detection in urine: building CCS databases to support food safety monitoring

Selective Androgen Receptor Modulators (SARMs) were initially developed for therapeutic purposes. However, despite their prohibition by the World Anti-Doping Agency (WADA) since 2008, they remain readily available, raising concerns about their potential misuse in Animal Husbandry. To counter such practices, analytical methods for anti-doping control must continuously evolve. Ion Mobility (IM) offers advantages for SARM detection, including increased selectivity, enhanced sensitivity, and the provision of collision cross section (CCS), as an additional molecular descriptor. In this context, the present study reports an interlaboratory comparison of 48 CCS values obtained for 30 SARMs using two IM platforms: travelling wave ion mobility (TWIMS) and trapped ion mobility (TIMS). TWIMS results showed a maximum variation of 0.40%, and TIMS of 0.34%, both well below the 2%, as suggested criterion. Overall, 92% of ions analysed in the interlaboratory comparison exhibited a deviation below 2%. Comparisons with CCS prediction tools revealed deviations well above 2%, highlighting the importance of experimental measurements. Finally, a case study on urine samples from bovines treated with Ostarine demonstrated that IM can improve confidence in analyte identification by providing CCS as an additional confirmation parameter, while also cleaning the signal.