Dispersive liquid–liquid microextraction followed by a back-extraction step was combined with HPLC-DAD for the determination of four parabens (. methyl-, ethyl-, propyl-, and butylparaben). Optimum extraction conditions were found as follows: 225 µL of chloroform, mL of ethanol, 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 mL min −1 and an injection volume of 20 µL. DAD was set at 258 nm to monitor the analytes. |
