Quantification of Arbutin in Cosmetics, Drugs and Food Supplements by Hydrophilic-Interaction Chromatography

Arbutin, the glucoside of hydroquinone, exists in two isomers, alpha-arbutin and beta-arbutin. The synthetic alpha isomer is mainly used as a skin brightening agent, while beta-arbutin occurs naturally, for instance in bearberry, and is used in drugs for treatment of lower urinary tract infections and as a food supplement. Since both isomers can be harmful at high concentrations, methods for their quantification are required. Classically they have been determined by reversed-phase chromatography, but separation of both isomers is often unsatisfactory. Here we present a simple and reliable method for quantification of alpha- and beta-arbutin based on hydrophilic-interaction chromatography. Prior to analysis, interfering compounds that would frequently be present in cosmetics and drugs, particularly biopolymers, were efficiently removed by precipitation with acetonitrile. In this paper, for separation, a Cyclobond I 2000 5 mu m 250 x 4.6 mm column was employed as stationary phase and acetonitrile/water 92/8 (v/v) was used as an eluent at a flow rate of 0.8 mL min(-1). For quantification, a UV detector operating at 284 nm was applied. Although analysis took less than 10 min, baseline separation of alpha- and beta-arbutin was achieved. The response was highly linear (r > 0.999) and the method had, for both alpha- and beta-arbutin, a LOD of 0.003% (w/w) and a LOQ of 0.009% (w/w). Moreover, the method showed excellent intra-day and inter-day repeatability with relative standard deviations in the range of 0.5% to 2.3% and 1.0% to 2.2%, respectively, with cosmetics, drugs and food supplements as samples.

Automated summary

This paper presents a simple and reliable method for quantification of alpha- and beta-arbutin using hydrophilic-interaction chromatography. The interfering compounds were efficiently removed prior to analysis, and baseline separation of both isomers was achieved. The method showed excellent repeatability and sensitivity for quantification of alpha- and beta-arbutin.