Electric field-assisted simultaneous microextraction of ultrashort- to long-chain perfluorocarboxylic acids prior to...

Sample preparation is critical in developing a sensitive and accurate method for the monitoring of ultrashort- to long-chain perfluorocarboxylic acids (PFCAs) in complex samples. However, it remains a formidable challenge in the simultaneous and efficient extraction of ultrashort- to long-chain PFCAs (U-L@PFCAs) due to their significantly different polarity. In this connection, the electric field-assisted microextraction (EFAM) was introduced for the first time to efficiently co-extract ultrashort- to long-chain species. According to the chemical properties of the studied U-L@PFCAs, a new microelectrode based on a monolithic adsorbent (MEMA) was tailored using diallylamine and 1,1,1,3,3,3-hexafluoroisopropyl acrylate as dual monomers and employed as the microelectrode of EFAM. Results disclosed that the application of opposite directions and different intensities of electric field at adsorption and desorption stages enhanced the increase of extraction efficiencies by 78.6-131% in comparison with the omission of electric field. In addition, the adsorption characteristics, behavior, and mechanism of MEMA@EFAM towards the investigated U-L@PFCAs were explored. Under the selected microextraction conditions, a sensitive and reliable method based on an isotope internal standard calibration curve technique for monitoring ultra-trace U-L@PFCAs in various environmental water and human urine samples was established by combining MEMA@EFAM with HPLC-MS/MS detection. Low detection limits of 0.13-1.4 ng/L and superior precision (RSDs varied from 2.8% to 9.1%) were achieved with minimum background interference. The present study provides a highly competitive alternative for the broad-spectrum monitoring of PFCAs.