Determination of monoamine neurotransmitters in human urine by carrier-mediated liquid-phase microextraction based on solidification of stripping phase.

A novel method was developed for the analysis of monoamine neurotransmitters (MNTs) in human urine by carrier-mediated liquid-phase microextraction based on solidification of stripping phase method (CM-LPME-SSP) coupled with high performance liquid chromatography-electrochemical detector (HPLC-ECD). By adding an appropriate carrier in organic phase, simultaneous extraction of hydrophilic analytes, MNTs, with high enrichment factors (22.6–36.1 folds) and excellent sample cleanup was achieved. A new strategy, solidifying the aqueous stripping phase in the back-extraction process, was developed to facilitate the collection of the stripping phase as small as a few microliters. Combined with HPLC-ECD analysis, the linear ranges of the established method were 0.015–2.0 μg/mL for NE, E, DA, and 0.020–2.0 μg/mL for 5-HT. The limits of detection and quantification were in the range of 5.5–10.8 ng/mL and 15–20 ng/mL, respectively. The relative recoveries were in the range of 87–108%, with intraday and interday relative standard deviations lower than 13%. This method was successfully applied to analysis of MNTs in real urine. [ABSTRACT FROM AUTHOR]