Rapid determination of trace phenols migrating into drinking water from plastic-based pipe materials and household water treatment equipment using vortex-assisted emulsification microextraction

Abstract

A simple and rapid vortex-assisted emulsification microextraction (VAEME) method combined with spectrophotometry was developed for the determination of trace phenols migrating into potable water from plastic-based pipe materials and household water treatment equipments. The oxidative coupling reaction of phenolic compounds with 4-aminoantipyrine was carried out employing potassium peroxodisulfate as the oxidant in alkaline medium. A cloudy mixture was formed facilitating mass transfer of the reaction products into the fine droplets of toluene. The extraction equilibrium was rapidly achieved within 3 min by a combination of vibration and heating. The extract was concentrated in the narrow neck of the vessel, and could be easily withdrawn with a syringe. The VAEME method effectively avoids the analytical errors resulting from fluid leakage, which often occurs during conventional liquid–liquid extraction with a separating funnel. Under the optimal conditions, linearity ranges of 0.2–180 μg L⁻¹ and detection limits of 0.08 μg L⁻¹ (expressed as C₆H₅OH concentration) were achieved. This approach was successfully applied in the determination of trace amounts of phenols in 36 solutions used to soak a variety of matrices. The recoveries were in the range of 86.0–99.8% and the relative standard deviations ranged from 0.53% to 6.5%. Compared with the official method, the proposed method was faster, more sensitive and required lower amounts of reagents.