A rapid, simple, and sensitive technique for the quantitative detection of fluoxetine and norfluoxetine enantiomers in biological fluids was developed based on the combination of field-amplified sample stacking (FASS)–related capillary electrophoresis (CE) with ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME). The extraction efficiency of UA-DLLME was strongly related to extraction time, salt concentration, type of extraction and dispersion solvents, and volume of extraction and dispersion solvents. The extracted fluoxetine and norfluoxetine enantiomers in a mixture of 50% methanol and 50% deionized water were efficiently stacked using FASS and then separated using cyclodextrin-modified CE. Under optimal conditions of FASS (chiral selector, 3 mM trimethyl-β-cyclodextrin; and background electrolyte, 100 mM phosphate buffer) and UA-DLLME (extraction solvent, 200 μL of acetone; and dispersed solvent, 50 μL of C₂H₂Cl₄ in 1 mL of the sample solution), the obtained enrichment factors of fluoxetine and norfluoxetine enantiomers reached approximately 2000. The linear ranges for the quantification of fluoxetine and norfluoxetine enantiomers were 0.3–150 and 0.6–150 nM, respectively. The relative standard deviations in peak areas and migration time for four analytes were less than 3.3% and 6.3%, respectively. The proposed system provided limits of detection (signal-to-noise ratio of 3) for four analytes corresponding to 0.1 nM. The precision and accuracy for urine and serum samples were less than 6.8 and 8.3%, respectively. These findings suggested that the proposed system exhibited a high potential for the reliable determination of fluoxetine and norfluoxetine enantiomers in clinical samples.

Graphical abstract

基于场放大样品堆叠（FASS）相关的毛细管电泳（CE）和超声辅助分散液-液的结合，开发了一种快速，简单，灵敏的定量检测生物流体中氟西汀和去氟西汀对映体的技术微萃取（UA-DLLME）。UA-DLLME的萃取效率与萃取时间，盐浓度，萃取和分散溶剂的类型以及萃取和分散溶剂的量密切相关。使用FASS将50％甲醇和50％去离子水的混合物中提取的氟西汀和去氟西汀对映体有效堆叠，然后使用环糊精修饰的CE进行分离。在FASS的最佳条件下（手性选择剂，3 mM三甲基-β-环糊精和背景电解质，₂ H ₂氯₄在1 mL样品溶液中），氟西汀和正氟西汀对映体的富集因子达到约2000。氟西汀和正氟西汀对映体的定量线性范围分别为0.3–150和0.6–150 nM。四种分析物的峰面积和迁移时间的相对标准偏差分别小于3.3％和6.3％。拟议的系统提供了对应于0.1 nM的四种分析物的检测限（信噪比为3）。尿液和血清样品的准确度和准确度分别低于6.8％和8.3％。这些发现表明，所提出的系统在临床样品中氟西汀和去氟西汀对映体的可靠测定方面具有很高的潜力。

图形概要