Polymeric ionic liquid sorbent coatings in headspace solid-phase microextraction: A green sample preparation technique for the determination of pesticides in soil

In this work, a green approach utilizing novel polymeric ionic liquid (PIL) coatings for headspace solid-phase microextraction (HS-SPME) of four current-use pesticides from soil samples was studied for the first time. Epoxiconazole, fluroxypyr, metribuzin, and oxyfluorfen were the target pesticides. Three PIL coatings containing 1-vinylbenzyl-3-hexadecylimidazolium bisKtrifluoromethypsulfonyllimide (PIL1 and PIL2) and 1-vinyl-3-(10-hydroxydecyl)imidazolium bis[(trifluoromethyl)sulfonyl]imide (PIL3) monomers, and 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide (PIL1) and 1,12-di(3-vinylbenzimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide (PIL2 and PIL3) crosslinkers were employed in this study. The performance of these PIL coatings was evaluated and compared with commercial SPME coatings based on polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polydimethylsiloxane (PDMS) at the different extraction temperatures (50-90 degrees C) and sampling times (15-60 min). HS-SPME at 90 degrees C for 60 min provided the highest sensitivity and adequate reproducibility for the majority of analytes. Despite having a lower thickness, PIL2 and PIL3 coatings provided similar extraction effectiveness of analytes, and 24-247% higher coating volume-normalized responses compared to the commercial PDMS/DVB coating. The use of the PIL1 sorbent coating resulted in excellent linearity (R-2 = 0.995-0.999) and lower detection limits (0.06-0.4 ng g(-1)) for all analytes. The optimized method provides acceptable recoveries of spiked concentrations with better performance (84-112%) achieved with the PIL1 coating. Compared to other known methods for target pesticides in soil, the proposed method provides the highest compliance with the principles of green analytical chemistry evaluated using Analytical Eco-Scale and Green Analytical Procedure Index tools.