LAUSR

This article reports for the first time a programmable-flow based mesofluidic platform that accommodates an electric field-driven liquid phase microextraction (µ-EME) in a fully automated mode. The miniaturized system is composed of a computer-controlled microsyringe pump and a multi-position rotary valve for handling aqueous and organic solutions at the low microliter volume, and acts as a front-end to on-line liquid chromatographic separation. The organic phase 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 µ-EME processed complex samples (such as urine and influent wastewater) using on-line heart-cut approaches. Using 5 µL of 1-octanol, 7.5 µL of untreated sample and 7.5 µL of acceptor solution (25 mM NaOH), and 250 V for only 10 min in a stopped-flow mode, the extraction recoveries for the µ-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%. .