Fully Automated Electric-Field-Driven Liquid Phase Microextraction System with Renewable Organic Membrane As a Front End to High Performance Liquid Chromatography

摘要

This article reports for the first time a programmable-flow-based mesofluidic platform that accommodates electric-field-driven liquid phase microextraction (mu-EME) in a fully automated mode. The miniaturized system is composed of a computer-controlled microsyringe pump and a multiposition rotary valve for handling aqueous and organic solutions at a low microliter volume and acts as a front-end to online liquid chromatographic separation. The organic membrane is automatically renewed and disposed of in every analytical cycle, thus minimizing analyte carry-over effects while avoiding analyst intervention. The proof-of-concept applicability of the automated mesofluidic device is demonstrated by the liquid chromatographic determination of nonsteriodal anti-inflammatory drugs in mu-EME processed complex samples (such as urine and influent wastewater) using online heart-cut approaches. Using 5 mu L of 1-octanol, 7.5 mu L of untreated sample and 7.5 mu L of acceptor solution (25 mM NaOH), and 250 V for only 10 mM in a stopped-flow mode, the extraction recoveries for the mu-EME of ibuprofen, ketoprofen, naproxen, and diclofenac exceed 40% in real samples. The flow-through system features moderately selective extraction regardless of the sample matrix constituents with repeatability values better than 13%.