Liquid–Gas–Liquid Microextraction as a Simple Technique for the Extraction of 2,4-Di-tert-butyl Phenol from Aqueous Samples

A solvent-free microextraction technique based on liquid–gas–liquid microextraction was investigated for the extraction and preconcentration of 2,4-di-tert-butyl phenol from aqueous samples. In this study 16 μL NaOH 1 M as acceptor phase was introduced in the lumen of a polypropylene hollow fiber, with one of its ends heat-sealed. A small piece (about 2 cm) of metallic wire was used to seal the other end of hollow fiber after introducing acceptor phase and before immersing of hollow fiber into the analyte solution. This configuration eliminated the need for a holder. The extraction procedure is simple and there is no necessity to adjust pH, salt content, temperature, etc. After extraction the acceptor phase was transferred to a 1-mL vial, 50 μL 0.5 M phosphoric acid was added and the sample was injected into the HPLC–DAD system. Detection was performed at 280 nm. Limit of detection is 30 ng mL⁻¹ and the relative standard derivation (n = 6) is 5.0%. An enrichment factor (EF) of about 30 is achievable.