Miniaturized dynamic liquid-liquid extraction of organophosphate triesters from blood plasma using the hollow fibre-based XT-tube extractor

摘要

A miniaturized liquid-liquid extractor for bioanalytical sample preparation is described. The extractor consists of a polypropylene hollow fiber mounted inside polytetrafluoreoehylene (PTFE) tubing by means of cross (X) connector and a tee (T) connector. all parts are commercially available, inexpensive, and easilyassembled. The aqueous sample, injected into a carrier flow, is pumped along the outside of the fiber and the organic phase, which also wets the pores of the hollow fibre wall, is pumped inside. eight organophosphate trimester (OPE) plasticisers/flame retardants were extracted from 50 μL spined blood plasma that has been mixed with 50 μL formic acid to denature plasma proteins. The organic phase was a mixture of hexane and methyl tert-butyl ether (MTBE). A high concentration of formic acid in the sample and of MTBE in the organic phase had positive effects on the recovery of some OPE. When investigating the recovery as a function of extraction time it was found that the extraction reached a maximum after 10 min, at a flow-rate of 15μL min~(-1). Recoveries varied between 40 and 80 with RSD around 4 for most compounds. The whole 150-μL extract was injected into a GC-MS system equipped with a programmed-temperature vaporization (PTV) injector. with the MS in selected-ion monitoring (SIM) mode, the LOD for triphenyl phosphate and 2-ethylhexyl diphenyl phosphate were 0.3 and 0.2 ng mL~(-1), respectively. More than 40 plasma extractions were performed wit the same fibre without any detectable change in extraction efficiency.