Cloud-point extraction is compatible with liquid chromatography coupled to electrospray ionization mass spectrometry for the determination of antazoline in human plasma

Abstract

Cloud-point extraction (CPE) is attracting increasing interest in a number of analytical fields, including bioanalysis, as it provides a simple, safe and environmentally-friendly sample preparation technique. However, there are only few reports on the application of this extraction technique in liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI–MS/MS) analysis. In this study, CPE was used for the isolation of antazoline from human plasma. To date, only one method of antazoline isolation from plasma exists—liquid–liquid extraction (LLE). The aim of this study was to prove the compatibility of CPE and LC-ESI–MS/MS and the applicability of CPE to the determination of antazoline in spiked human plasma and clinical samples.Antazoline was isolated from human plasma using Triton X-114 as a surfactant. Xylometazoline was used as an internal standard. NaOH concentration, temperature and Triton X-114 concentration were optimized. The absolute matrix effect was carefully investigated. All validation experiments met international acceptance criteria and no significant relative matrix effect was observed. The compatibility of CPE and LC-ESI–MS/MS was confirmed using clinical plasma samples. The determination of antazoline concentration in human plasma in the range 10–2500ngmL−1 by the CPE method led to results which are equivalent to those obtained by the widely used liquid-liquid extraction method.