HPLC-UV Analysis of Clobetasol Propionate in Cream Samples

Chromolith^® HighResolution RP-18e, 100x2mm (1.52322)

Water/methanol 25/75 (v/v)

isocratic

189 µL/min

53 bar (768 psi)

25 °C

UV @ 240 nm, micro flow cell (1.4 µL/7 mm)

4 µL

Cream sample spiked: 1 g of homogenized cream spiked with clobetasol propionate at 3 mg/g in a 50 mL volumetric flask, add 30 mL of water/methanol 30/70 (v/v) and sonicate for 5 minutes. Fill up to volume with water/methanol 30/70 (v/v). Transfer 3 mL of this suspension into a 25 mL volumetric flask and fill up to volume with diluent. Resulting cream sample concentration in final dilution is 2.4 mg/mL. Pass through a 0.45 µm syringe filter before injection.)

Bleaching or skin whitening creams are widely used to reduce melamin content in the skin, and for such products, analytical quality control is required. An often used active ingredient in these whitening creams is clobetasol propionate.

This application focuses on the analysis of clobetasol propionate in a cream matrix using a simple sample preparation process (dilution & filtration) and a monolithic silica Chromolith^® HighResolution RP-18 endcapped (RP-18e) column 100x2 mm on an HPLC-UV instrument with a micro-detection cell. The monolithic silica, due to its bi-modal pore structure, provides high efficiency and matrix tolerance at low back pressure. The external calibration with 8 calibrators in methanol in the range of 1.0–101.6 µg/mL resulted in a linearity of R² = 0.9997. The resulting limit of detection (LOD) was less than 3 µg/mL and the limit of quantitation (LOQ) was less than 7 µg/mL in the final dilution sample, representing limits for the cream samples of 0.93 mg/g (LOD) and 2.80 mg/g (LOQ). RSD for a cream sample spiked at 3 mg/g was 1.2%, and the spike recovery was determined at 94% (2.82 mg/g).

APP_549

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