chemometrics-assisted liquid phase microextraction based on deep eutectic solvent followed by gas chromatography for determination of polycyclic aromatic hydrocarbons in aqueous and juice samples

Abstract: nowadays, deep eutectic solvents (dess), a new generation of solvents, are widely used in extraction procedures because of their low cost, low toxicity, and biodegradability characteristics. one of the main features of dess is their ability to be used to extract a wide range of organic pollutants such as polycyclic aromatic hydrocarbons (pahs), known as one of the contaminants of emerging concerns (cecs), from aqueous matrices. extraction from complex matrices requires the simultaneous study of different extraction variables. in this regard, chemometric methods have been widely used to maximize extraction efficiency [1-3]. in the present study, des-based liquid phase microextraction (des-lpme) methodology followed by gc-fid in combination with chemometrics was studied in order to determine 13 pahs in aqueous samples. in the first step, different dess were synthesized based on previous studies, and a mixture of 4-chlorophenol and choline chloride in a 2:1 molar ratio was selected as the best extracting solvent. after that, important lpme parameters were optimized using the central composite design (ccd) and the simplex optimization method. on this matter, the optimal des volume, extraction time, temperature, and salt amount were 112μl, 9.14 min, 72◦c, and 75 mg, respectively. in the next step, artifacts in gc chromatograms such as baseline and elution time shift were corrected using asymmetric least squares (asls) and correlation optimized warping (cow) algorithms [4]. next, both univariate and multivariate calibrations were performed in seven concentration levels (0.2-70 ppb) with partial least squares regression (pls-r) and artificial neural network (ann). for pls-r as the model with better performance, sensitivity (sen), analytical sensitivity (γ), limit of detection (lod), limit of quantitation (loq) and root mean square error of prediction (rmsep) were calculated for each pah. for all pahs, except for fluorene with r2=0.87, the calculated r2 was obtained at about 99%. finally, to test the applicability of the proposed methods in real samples, sea waters, as well as orange and apple juices, were analyzed at 10 and 30 ppb concentration levels. the relative recoveries were obtained in the range of 83.4%-109% for 10 ppb and 78.4%-103% for 30 ppb. in conclusion, the developed method based on des-lpme combined with gcfid and chemometric techniques can be used for determining pahs in real matrices.