Determination of 13 Janus Kinase Inhibitors in Anti-Alopecia Cosmetics by Ultra-High Performance Liquid Chromatography-Tandem Triple Quadrupole Composite Linear Ion Trap Mass Spectrometry

The study developed a method using UHPLC-Q-TRAP/MS to detect 13 JAK inhibitors in anti-alopecia cosmetics, offering an accurate, simple, fast, and highly specific approach for quantitative analysis and qualitative screening. This method prevents false positives and provides a new way to detect illegal additions of JAK inhibitors in hair loss prevention cosmetics, supporting cosmetic safety regulation and deterring illegal activities, as demonstrated in the 2024 national cosmetic sampling inspection.