Application of liquid–liquid–liquid microextraction and ion-pair liquid chromatography coupled with photodiode array detection for the determination of chlorophenols in water

A method termed as liquid–liquid–liquid microextraction was utilized to extract chlorophenols from water. The extracted chlorophenols, present in anionic form, were then separated, identified, and quantitated by ion-pair high-performance liquid chromatography with photodiode array detection (HPLC/DAD). For trace chlorophenol determination using HPLC/DAD, the chlorophenolate anion provides a better ultraviolet spectrum for quantitative and qualitative analyses than does uncharged chlorophenol. This is due to the auxochromic effect of the phenolate anion. In the study, experimental conditions such as organic phase identity, acceptor phase volume, sample agitation, extraction time, acceptor phase NaOH concentration, donor phase HCl concentration, salt addition, and UV absorption wavelength were optimized. Relative standard deviations (RSD, 2.3–5.4%), coefficients of determination (r2 0.9994–0.9999), and detection limits (0.049–0.081 ng mL−1) of the proposed method were investigated under the selected conditions. The method was successfully applied to analyses of reservoir and tap water samples, and the relative recoveries of chlorophenols from the spiked reservoir and tap water samples were 94.1–100.4% and 87.8–101.2%, respectively. The proposed method is capable of identifying and quantitating each analyte to 0.5 ng mL−1, confirming the HPLC/DAD technique to be quite robust for monitoring trace levels of chlorophenols in water samples.