Ionic liquid molecularly imprinted polymers for application in pipette-tip solid-phase extraction coupled with gas chromatography for rapid screening of dicofol in celery

Abstract

A new type of ionic liquid molecularly imprinted polymers (IL–MIPs) synthesized by precipitation polymerization using 1-allyl-3-methylimidazolium bromide as an auxiliary solvent and α-chloro-dichlorodiphenyltrichloroethane (α-chloro-DDT) as the template was applied as a selective sorbent of minimized pipette tip-solid-phase extraction (PT-SPE) for rapid isolation and extraction of dicofol (DCF) from celery samples. The pretreatment procedure of celery samples involved only 2.0mg of IL–MIPs, 0.8mL of acetonitrile–water (ACN–H2O; 1:1, v/v) (washing solvent), and 1.0mL of acetone–10% acetic acid (HOAc) (elution solvent). Compared with molecularly imprinted polymers (MIPs), ionic liquid–non-imprinted polymers (IL–NIPs) and conventional sorbents such as C18, Si, NH2, and Al2O3–N, IL–MIPs showed higher adsorption and purification capacity to DCF in aqueous solution. Good linearity for DCF was observed in the range from 2.3 to 232.5ngg−1 (r2=0.9995). The average recoveries at three spiking levels ranged from 86.6% to 101.9% with relative standard deviations (RSDs) of ≤6.5% (n=3). The presented IL–MIPs–PT-SPE–GC/ECD method combines the advantages of MIPs, IL, and PT-SPE, and can be used in aqueous conditions with high affinity and selectivity to analytes of complex samples.