Simultaneous HPLC-DAD Determination of Benzotriazole UV Absorbers in Cosmetics with LC-MS/MS Confirmation

Benzotriazole UV filters (UV-320, UV-326, UV-327, UV-328, UV-329, UV-350) are classified as substances of very high concern (SVHC) under EU REACH, while UV-328 is listed as a Persistent Organic Pollutants (POP) by the Stockholm Convention. Currently, no standard method can simultaneously quantify all six restricted compounds in cosmetics, Herein, an ultrasonic-assisted ternary solvent extraction coupled with high-performance liquid chromatography (HPLC)-diode array detection (DAD) quantification and HPLC–tandem mass spectrometry (MS/MS) confirmatory method was developed for five typical cosmetic matrices (aqueous, gel, cream, powder, wax). Samples were extracted with tetrahydrofuran/methanol/water (6:2:2, v/v/v) via two-step sonication. Six analytes were fully baseline separated within 15 min on an Ultimate-XB-C18 column using isocratic methanol–water (97:3, v/v) at a flow rate of 0.8 mL/min and 340 nm. The method showed good linearity (R2 > 0.999) over the range of 0.3–20 μg/mL, corresponding to 15–1000 mg/kg in cosmetic samples. The limit of detection (LOD) and limit of quantification (LOQ) were 5 and 15 mg/kg, respectively. Matrix-matched calibration was adopted to eliminate matrix effects. At three spiked concentration levels, average recoveries across five blank matrices ranged from 91.5% to 106.3%, with intra-day RSDs (n = 6) of 1.2–5.8%. Samples with positive HPLC signals or chromatographic interference were further verified by LC-MS/MS Compared with existing methods, this protocol covers all six REACH-regulated benzotriazole derivatives and exhibits superior compatibility with waxy and cream cosmetic matrices. The proposed method is simple, rapid, reliable and suitable for routine supervision and import/export inspection of cosmetic products.