DBDI-MS for rapid threshold-based screening of anabolic agents in unregulated supplements

Anabolic androgenic steroids and selective androgen receptor modulators are widely misused and often present in unregulated dietary supplements. To enable rapid screening without extensive preparation, we evaluated a commercial dielectric barrier discharge ionization source mounted on Orbitrap Exploris 120, and benchmarked its detection performance against a validated LC–MS/MS method to assess how well the DBDI approach identifies analytes relative to the laboratory gold standard. Samples were analyzed by a simple dilute-and-shoot protocol with repeated injections into the DBDI source. Target [M + H] + ions were extracted within a ± 5 ppm window and integrated as peaks within the injection regions. Simplified matrix-matched calibrations were used to calculate LODs (3.3 × σ/slope), while multi-level calibrations (0.1–10 μg/mL) confirmed linearity and supported threshold setting. A pre-specified decision rule was applied: thresholds were expressed as minimum internal standard (IS)-normalized peak area, and any signal above this cutoff was classified as positive. Data evaluation was automated and generated as binary output, i.e., analyte detected/not detected. In 24 real-world supplements (181 sample–analyte pairs), blinded cross-validation with LC–MS/MS showed 180 true matches and one false positive (99.4% agreement). Analysis time was 1–2 min per sample, compared with 12–15 min for LC–MS/MS, and the method ensured detection below label claims, with cutoffs corresponding to 12–83% of typical analyte content. Propranolol served as a low-cost, generic IS, demonstrating the feasibility of normalization without isotopically labeled standards. These results demonstrate that DBDI–MS enables rapid, threshold-based, automated screening of anabolic agents in supplements with high concordance to LC–MS/MS, thereby representing an initial step toward the development of confident ambient ionization MS-based detection approach.