A rapid and reliable size-exclusion chromatographic method for determination of kojic dipalmitate in skin-whitening cosmetic products

A size-exclusion chromatographic method has been developed to determine the relatively novel skin-whitening agent called kojic dipalmitate (KDP) in skin-whitening cosmetic products. Preliminary experiments were carried out in order to select the solvent for standard and sample solution, and also for mobile phase composition. A PLGel Mixed-D (polystyrene/divinylbenzene co-polymer) column and isocratic mobile phase of pure tetrahydrofuran (at 1.5 mL min(-1) flow rate) were used. Detection was carried out by means of an UV/vis spectrometry detector set at 248 nm. A study of interferences reveals that KDP can be determined without interferences coming from cosmetic matrices. Most other cosmetic ingredients usually employed in skin-whitening cosmetic products, such as other whitening agents and common UV filters, do not interfere. The accuracy and precision of the proposed method was tested by the analysis of six laboratory-made and five commercial skin-whitening cosmetic samples. The sensitivity and limit of detection (3 microg mL(-1)) obtained are suitable for the analysis of this type of samples. The chromatographic run takes less than 8 min to complete. All these features make the method easy to apply to quality control in the cosmetic industry.