Dispersive liquid-liquid microextraction of parabens from pharmaceuticals and personal care products prior to their determination using HPLC-DAD

Abstract

Dispersive liquid–liquid microextraction followed by a back-extraction step was combined with HPLC-DAD for the determination of four parabens (i.e. methyl-, ethyl-, propyl-, and butylparaben). Optimum extraction conditions were found as follows: 225 µL of chloroform, 0.75 mL of ethanol, 7.5 mL of aqueous solution and within an extraction time of 15 s. Back-extraction into 100 µL of 50 mM sodium hydroxide solution within 20 s resulted in a reversed-phase HPLC-compatible extract. The analytes were separated at 20 °C using methanol (A) and water (B), 40:60 (A:B, v/v) as the mobile phase, a flow rate of 1.0 mL min−1 and an injection volume of 20 µL. DAD was set at 258 nm to monitor the analytes. Limits of detection and quantitation were as low as 0.1 and 0.3 µg mL−1 , respectively. Coefficients of determination (R2) were higher than 0.9950 and percentage relative recoveries were found in the range of 86.5–114.5% for the four parabens from pharmaceuticals and personal care products.