Micellar electrokinetic biofluid analysis of biogenic amines using on-line sample concentration and UV laser-induced native fluorescence detection

A simple and sensitive sweeping micellar electrokinetic chromatography method coupled with UV laser-induced native fluorescence detection has been developed for quantitative analysis of biogenic amines in biofluids. The background electrolyte comprised 30 mmol L−1 phosphoric acid and 20 mmol L−1 sodium dodecyl sulfate. The concentration limits of detection of analytes using sweeping-micellar electrokinetic chromatography (sweeping-MEKC) were in the range 7–100 nmol L−1, which were 250–3600-fold improvement for dopamine, DOPA and epinephrine compared with conventional capillary zone electrophoresis. An improvement of approximately 20-fold was observed for all analytes compared with typical micellar electrokinetic chromatography conditions. Baseline separation was achieved for the all analytes within 12 min and migration-time and peak-area repeatability were better than RSD 0.35% and 5.68%, respectively. The developed method was applied to measure the biogenic amines in biofluids extracted from wheat phloem sap, human plasma and human urine.