Low Density Solvent Ion Pair Dispersive Liquid–Liquid Micro‐Extraction – An Economic Method for Extraction of Phthalic Acids

Abstract

A simple and economic analytical method based on low density solvent ion‐pair dispersive liquid–liquid micro‐extraction using high performance liquid chromatography–diode array detection has been used for the determination of phthalic acid, terephthalic acid, and iso‐phthalic acid in aqueous samples. In this work, 0.75 mL methanol (as a disperser solvent), 90 μL toluene (as an extraction solvent), and 15 μL tri‐butyl amine (as an ion pair reagent) were injected into aqueous phase. After centrifuging (at 4000 rpm for 5 min), the analyte ion pairs were extracted into toluene. The collected toluene was withdrawn and transferred into a microtube. The transferred toluene was evaporated under a stream of nitrogen at room temperature to dryness. Then, 10 μL of the mobile phase was added to the microtube to re‐dissolve the residues. Under the optimized conditions, limits of detection and quantification were calculated in the range of 0.12–0.34 and 0.37–1.06 ng mL−1, respectively. The linear range of the developed method was obtained as 0.37–10000 ng mL−1. Enrichment factors and extraction recoveries were from 82 to 98% and 411–492, respectively. Finally, different aqueous samples such as tap water, mineral water, cola, lemon juice, vinegar, and dextrose and NaCl injection solutions were analyzed successfully by the developed procedure and the selected analytes were found in some of them in the range of 6.2–72 ng mL−1.