In-syringe homogeneous liquid–liquid microextraction as an economical, convenient, and one-step analytical method for the extraction and preconcentration of five plasticizers and one antioxidant from different city tap water samples

Abstract

In this study, an analytical method called in-syringe homogeneous liquid–liquid microextraction was developed and applied for the extraction and preconcentration of plasticizers including di ethyl phthalate, di isobutyl phthalate, di-n-butyl phthalate, di(2-ethylhexyl) adipate, and di(2-ethylhexyl) phthalate and one antioxidant, (butylated hydroxytoluene). Only a few microliters of dibutyl amine was used as the extraction solvent. This switchable solvent became miscible in the solution of interest by adding acetic acid at µL-level to extract the analytes. Also, the addition of sodium carbonate (in mg-level) into the solution led to the release of carbon dioxide, which facilitated the extraction of plasticizers into the extractant. Also, sodium carbonate caused to the regeneration of the extractant in the upper narrow bore of the syringe. The enriched analytes were determined by a gas chromatographic equipped with a flame ionization detector. Under the optimum conditions, extraction recoveries and enrichment factors were obtained in the ranges of 39–78 % and 196–394, respectively. Also, the limits of detection and quantification were in the ranges of 1.76–12.51 µg/L and 5.80–41.28 µg/L, respectively, and the r2 values were equal to or better than 0.991. Development of the method as a one-step analysis processed which was electrically independent in extraction and preconcentration stage (no centrifugation or vortexing) and inexpensive. The use of only µL-level of organic solvent, convenient operation, and short extraction time are the other highlights of the method. This method was successfully applied to the extraction, preconcentration, and determination of several plasticizers in eight different city water samples.