Innovative Method for the Analysis of Dexpanthenol in Hair Care Products

Background: Dexpanthenol is a widely used humectant in hair care products, especially anti-hairfall products. The hair care industry is highly regulated in East Asia and treats products containing the combination of dexpanthenol, zinc pyrithione, and nicotinamide (vitamin B₃) as quasi-drugs. Objective: Because dexpanthenol lacks a UV chromophore, existing methodologies for analysis in finished products include pretreatments and/or HPLC-UV analysis at low wavelengths at which poor signal-to-noise is observed. These time-consuming methods lack the robustness needed for routine use in quality laboratories. This has resulted in the need for a simple, fast, accurate, and robust UHPLC-MS method to quantify dexpanthenol in hair care products that could be easily adapted in quality laboratories. Methods: The MS detection was performed in positive ion mode with data acquired in single-ion recording for dexpanthenol (206.14 m/z), dexpanthenol-d₆ (212.29 m/z), and Leucine Enkephalin acetate salt (556.28 m/z). Quantitation was performed using peak area ratio of dexpanthenol to the internal standard. Results: The resulting linear curve R² was 0.9998 with sample precision RSDs <2.5%. The accuracy recoveries were within 2% and the robustness results were within 3% of the nominal conditions. Conclusions: The resulting method for the quantitation of dexpanthenol is fast, accurate, and robust in the range of 170.24-1024.5 ng/mL in shampoo and conditioner, which is easily adaptable in quality laboratories. Highlights: This study determined optimal sample preparation and UHPLC-MS conditions to quantify dexpanthenol in finished hair care products.