Durable porous polyaniline supported ionic liquid coating for the highly effective solid phase microextraction of trace fatty alcohols in drinks

Abstract

A polyaniline (PANI)-ionic liquid (IL) based solid phase microextraction (SPME) coating is presented. The porous PANI was electrodeposited on a stainless steel wire, and then it was coated with IL. The porous PANI could well immobilize IL, and the obtained hybrid coating could be used for more than 110-times of adsorption/desorption. The extraction efficiency of different ILs (i.e. 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HOEMim]NTf₂)) based coatings was compared for different analytes (i.e. benzene, aryl halide, phenolic, amine and fatty alcohol compounds). It was found that the PANI-[HOEMim]NTf₂ coating exhibited quite high extraction efficiency for fatty alcohol compounds (i.e. 1-octanol, 1-nonanol, n-decanol, 1-undecanol and dodecanol). The dependence of the gas chromatograph peak areas of the analytes after SPME on their initial concentration in solution was investigated and the corresponding isothermal adsorption equation was displayed. After optimizing the conditions, linear detection ranges of 0.05 ng mL⁻¹ to 100 ng mL⁻¹ were obtained for different fatty alcohol compounds. The limits of detection were 0.0061–0.018 ng mL⁻¹. The relative standard deviations (RSD) of the peak area were below 8.4% for five repetitive extractions of solutions containing 25 ng mL⁻¹ fatty alcohol compounds. The proposed method was applied to the determination of the analytes in two tea drinks, and 57 ng mL⁻¹ of 1-nonanol was found in a jasmine tea sample, while 2.2 ng mL⁻¹ of 1-undecanol was found in a rock sugar lemon sample, but other analytes were below their detection limits. The recoveries for spiked fatty alcohols were 84.9–117.6%, and the RSDs were lower than 12.2%.