title: A novel fatty-acid-based in-tube dispersive liquid-liquid microextraction technique for the rapid determination of nonylphenol and 4-tert-octylphenol in aqueous samples using high-performance liquid chromatography-ultraviolet detection.
abstract: In this study, a novel fatty-acid-based in-tube dispersive liquid-liquid microextraction (FA-IT-DLLME) technique is proposed for the first time and is developed as a simple, rapid and eco-friendly sample extraction method for the determination of alkylphenols in aqueous samples using high-performance liquid chromatography-ultraviolet detection (HPLC-UV). In this extraction method, medium-chain saturated fatty acids were investigated as a pH-dependent phase because they acted as either anionic surfactants or neutral extraction solvents based on the acid-base reaction caused solely by the adjustment of the pH of the solution. A specially designed home-made glass extraction tube with a built-in scaled capillary tube was utilized as the phase-separation device for the FA-IT-DLLME to collect and measure the separated extractant phase for analysis. Nonylphenol (NP) and 4-tert-octylphenol (4-tOP) were chosen as model analytes. The parameters influencing the FA-IT-DLLME were thoroughly investigated and optimized. Under the optimal conditions, the detector responses of NP and 4-tOP were linear in the concentration ranges of 5-4000 μg L(-1), with correlation coefficients of 0.9990 and 0.9996 for NP and 4-tOP, respectively. The limits of detection based on a signal-to-noise ratio of 3 were 0.7 and 0.5 μg L(-1), and the enrichment factors were 195 and 143 for NP and 4-tOP, respectively. The applicability of the developed method was demonstrated for the analysis of alkylphenols in environmental wastewater samples, and the recoveries ranged from 92.9 to 107.1%. The extraction process required less than 4 min and utilized only acids, alkalis, and fatty acids to achieve the extraction. The results demonstrated that the presented FA-IT-DLLME approach is highly cost-effective, simple, rapid and environmentally friendly in its sample preparation.
authors.affiliation: Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan.
authors.forename: Hou-Kuang
authors.initials: HK
authors.lastname: Shih
authors.affiliation: Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan.
authors.forename: Ting-Yun
authors.initials: TY
authors.lastname: Shu
authors.affiliation: Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan; CME Food Testing Laboratory, Chi Mei Entech Co. & Ltd., No. 5, 32rd Road, Industrial Park, Taichung 408, Taiwan.
authors.forename: Vinoth Kumar
authors.initials: VK
authors.lastname: Ponnusamy
authors.affiliation: Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan. Electronic address: jfjen@dragon.nchu.edu.tw.
authors.forename: Jen-Fon
authors.initials: JF
authors.lastname: Jen
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005227:Fatty Acids / Q000737:chemistry*; D059627:Liquid Phase Microextraction / Q000379:methods*; D010636:Phenols / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D005227:Fatty Acids; D010636:Phenols; C025256:nonylphenol; C105260:4-tert-octylphenol
keywords: Alkylphenols; Aqueous sample; Fatty acid; High-performance liquid chromatography; In-tube dispersive liquid–liquid microextraction