Application of Achiral and Chiral High-Performance Liquid Chromatography Methods for Determination of Lactic Acid in Cosmetic Products

Lactic acid is a widely used component in cosmetics such as hair care products. High concentration of lactic acid or inappropriate enantiomeric form can have a negative impact on the skin. This study focuses on the development of methods of analysis for the separation, enantioseparation and determination of lactic acid in cosmetics and the confirmation of its enantiomeric form. Achiral reversed-phase high-performance liquid chromatography (RP-HPLC) on a C18 stationary phase and hydrophilic interaction liquid chromatography (HILIC) on an amino-propyl stationary phase, combined with diode array detection (DAD; 210 nm), were applied for analysis. Chiral HPLC-DAD on a teicoplanin-based stationary phase was an effective method for verification of the enantiomeric form, confirming L-lactic acid in tested samples. The complex samples were treated by solid-phase extraction using an anion-exchange adsorbent. Recovery studies showed good results, 76.1–91.8% (RSD ≤ 5.0%). The methods provide linearity of response in the concentration ranges tested (R2 > 0.996). This study demonstrated several approaches to the HPLC-DAD determination of lactic acid and proposed an effective sample preparation procedure. Developed methods were rapid, simple and applicable in the routine analysis of cosmetics for monitoring the safety of products.