Advances in steroid purification for novel techniques in carbon isotope ratio mass spectrometry of doping control

Doping detection is a critical tool for maintaining fairness in competitive sports. Steroids are widely abused due to their ability to promote protein synthesis, enhance muscle growth, and improve athletic performance, leading to significant unfair competition. Carbon isotope ratios (CIRs) are effective in distinguishing between endogenous and exogenous steroid sources, making steroids an ideal target for isotope ratio analysis in anti-doping analysis. High-precision isotope ratio measurements using Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-IRMS) require high separation between the target steroid and adjacent compounds to avoid interference. However, steroid concentrations in biological matrices like urine and blood are often trace and accompanied by a large number of coexisting interferents, making purification challenging. These limitations have partially restricted the use of compound-specific isotope analysis in doping detection. This review highlights the latest advancements over the past decade in sample preparation, liquid-phase purification, and both gas-phase and liquid-phase isotope ratio mass spectrometry (IRMS) techniques. By summarizing the application of these methods in anti-doping efforts and exploring future research directions, this review aims to enhance the precision and reliability of steroid doping detection technologies, providing scientific support for anti-doping efforts and identifying the abuse of steroids.