Study of XAD-2 adsorbent for the enrichment of trace levels of phthalate esters in hydroalcoholic food beverages and analysis by gas chromatography coupled with flame ionization and ion-trap mass spectrometry detectors

An analytical method based on solid-phase extraction (SPE) with Amberlite XAD-2 adsorbent used as stationary phase for determining phthalate esters (PAEs) in hydroalcoholic food beverages by GC-FID (and peak confirmation by GC-IT/MS) has been set up. The XAD-2 resin shows excellent properties for determining PAEs in solutions at very large alcoholic range (10-40% v/v): 500 mL of hydroalcoholic solution spiked with a PAE mixture solution (20 pg mu L-1 of each PAE) and containing 25 g L-1 of NaCl are passed onto a cartridge containing 500 mg XAD-2 adsorbent and re-extracted for GC analysis. The effects of NaCl concentration (0, 12,25 and 50 g L-1) and different solvents (CS2, toluene, acetone, n-hexane, ethyl acetate) are extensively studied as well the PAE recoveries both in hydroalcoholic aqueous solutions (ranging between 94% and 103% with a Relative Standard Deviation, RSD, below 8.3) and spiked (5, 10 and 25 pg mu L-1 of each PAE) real samples (between 90% and 106% with a RSD below 9.9). The correlation coefficients (R-2) of each PAE vary between 0.9830 and 0.9950 and they are calculated in the linear range 5-100 pg mu L-1. The limits of detection (LOD) in GC-FID vary between 1.21 and 2.51 pg mu L-1 (RSD <= 11.1) whereas the Limits of Quantification (LOQ) range between 2.42 and 5.03 pg mu L-1 (RSD <= 8.9) whereas the infra-day and inter-day repeatabilities calculated as RSD for hydroalcoholic solutions, are between 6.5% and 13.7%. (C) 2013 Elsevier Ltd. All rights reserved.