Preparation of new polymeric phases for thin-film liquid phase microextraction (TF-LPME) of selected organic pollutants

Abstract

Thin films made of a polymer (cellulose triacetate, CTA) and a plasticizer have been studied as novel sorptive phases for chlorpyrifos, triclosan and tonalide. The preparation is reproducible and only requires the plasticizer to be added into an organic dispersion containing CTA. The evaporation of the solvent leaves an easy to manipulate continuous and homogeneous thin film, which has been investigated in terms of both composition and extraction efficiency for the different compounds. Six different plasticizers (namely dibutyl sebacate, bis(2-ethylhexyl) sebacate, bis(2-ethylhexyl) phthalate, bis(1-butylpentyl) adipate, 2-nitrophenyl octyl ether and 2-fluorophenyl 2- nitrophenyl ether) with different chemical structure and physical properties, such as lipophilicity, dielectric constant and viscosity, have been incorporated in the CTA matrix and the resulting polymeric membranes have been characterized by different techniques (scanning electron microscopy, thermal techniques, and contact angle). Preliminary tests were undertaken in 0.01 M NaCl solution enriched with 100 μg L-1 of each analyte to study the kinetics and efficiency of extraction. All analytes were effectively extracted after 6 h with all the polymeric phases, with different kinetics. Among the different elutants tested, ethyl acetate provided satisfactory recovery values. The membrane made of CTA and dibutyl sebacate has been selected and successfully applied for the microextraction of pollutants in simulated natural water, river water and a wastewater effluent with trace concentrations added (0.2–2 μg L-1) before GC–MS determination. The overall method is easy to perform and provides good reproducibility (RSD < 10%) and recoveries higher than 80%