Determination of retinyl palmitate in ointment by HPLC with diode array detection

A simple and rapid HPLC with diode array detection method was developed for the determination of retinyl palmitate present together with other active substances in an ointment. Chromatographic separation was performed on 100 RP-18 Lichrospher column of particle size 5 microm. The mobile phase was methanol:water (98:2, v/v) and flow rate was 2.0 mL/min in isocratic mode. Samples were analyzed for 30 min. Spectophotometric detection was conducted at 325 nm. Under these conditions, the method featured high sensitivity, good precision and comparability of results as proven by the method validation and statistical analysis of the results. The limits of detection and determination were 0.4317 mg/100 mL and 1.3081 mg/100 mL, respectively, recovery values were measured at three levels 80%, 100% and 120% and yielded 101.05%, 101.34% and 100.43%, respectively. The linearity range was checked from 2 mg/100 mL to 10 mg/100 mL. The precision and inter-day precision of the method was expressed by relative standard deviation value and did not exceed 1.68%.