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 μL-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 μL-1 of each PAE) real samples (between 90% and 106% with a RSD below 9.9). The correlation coefficients (R2) of each PAE vary between 0.9830 and 0.9950 and they are calculated in the linear range 5-100 pg μL-1. The Limits of Detection (LOD) in GC-FID vary between 1.21 pg μL-1 and 2.51 pg μL-1 (RSD ⩽ 11.1) whereas the Limits of Quantification (LOQ) range between 2.42 pg μL-1 and 5.03 pg μL-1 (RSD ⩽ 8.9) whereas the infra-day and inter-day repeatabilities calculated as RSD for hydroalcoholic solutions, are between 6.5-13.7%.