Simultaneous determination of allantoin and glycolic acid in snail mucus and cosmetic creams with high performance liquid chromatography and ultraviolet detection

A new methodology for simultaneous quantitative analysis of allantoin and glycolic acid in snail mucus and cosmetic creams was developed. HPLC separation was achieved a Synergi-Hydro RP column within 7 min using isocratic elution with potassium phosphate (pH 2.7; 10 mM) at a flow rate of 0.7 mL/min at 30 °C. Sample pretreatment was performed by dilution of mucus or cosmetic cream in the elution buffer, heating at 60 °C for 20 min, adjusting the pH to 2.9 and purification with hexane extraction. Linearity was determined with spiked samples and the LLOQ values of 0.0125 and 0.2500 mg/mL were determined for allantoin and glycolic acid, respectively. Accuracy and intra- and inter-day repeatability were studied at three levels of concentrations (0.04, 0.08 and 0.16 mg/mL for allantoin and 0.1, 1.5 and 4.0 mg/mL for glycolic acid) using spiked mucus and cream base samples; mean values of recovery were in the range of 96.81–102.42% in all matrices tested, whereas the respective RSDs (%Relative Standard Deviation) were less than 3.04% in all cases. Spiked mucus and cream samples were stable (RSD < 4.16 and relative error < 4.34%) at room temperature and at 4 °C for 1 week and at −18 °C for 6 months; samples were also stable after three freeze-thaw cycles. The method was applied to the analysis of different lots of snail mucus, and of three commercial creams containing snail mucus.