Selective determination of dihydroxyacetone in self-tanning creams by HPLC as pentafluorobenzyloxime derivative

A new rapid and specific method for the determination of dihydroxyacetone (DHA) in self-tanning creams by reversed phase HPLC with UV detection was developed. DHA, together with hydroxyacetone (HA), used as internal standard, was extracted from the cream samples in a NaCl saturated aqueous solution and a small aliquot derivatized with pentafluorobenzylhydroxylamine (PFBHA) solution (10mg/mL) . The data on the time-course of the reaction showed that derivatization was completed after 5 min at room temperature in a citrate buffer at pH 4.0. The quickly formed oximes were isolated from the reaction mixture in acetonitrile after addition of NaCl saturated solution. The rapid chromatographic separation on a reversed phase C-18 column using a simple acetonitrile/water mixture followed by detection at 262 nm allowed a selective estimation of DHA in self-tanning creams currently on the national market. Quantitative yields of the oxime formation was verified by comparing responses of DHA subjected to the described procedure and of synthetic derivative previously prepared. Linearity (r2≥ 0.997), recovery (97÷105%), LOD (20 nmol) and precision (RSD ≤ 3.52%) of the method were tested.