Highly sensitive trivalent copper chelate-luminol chemiluminescence system for capillary electrophoresis detection of epinephrine in the urine of smoker

Epinephrine (EP) is one of the most important neurotransmitters and hormones. Some previous literatures show that there is a close relation between its release and smoking. To compare the levels of EP in urines of smokers and nonsmokers, a sensitive chemiluminescence (CL) system, luminol-diperiodatocuprate (III) (K-5[Cu(HIO6)(2)]. DPC), has been developed and validated for the determination of EP after CE separation. The DPC-luminol-EP CL reaction showed very intensive emission and fast kinetic characteristics, thus led to a high sensitivity in the flow-through detection mode for capillary electrophoresis. With the peak height as a quantitative parameter, the relative CL intensity was linear with the EP concentration in the range of 2.0-400 ng/mL, with a limit of detection of 0.82 ng/mL (S/N = 3). The reproducibility was assessed by intra- and inter-day relative standard deviations (RSDs) for 11 replicate determinations of EP standard samples at low, medium and high concentrations. The intra- and inter-day RSDs for CL signals were 5.5%-6.6% and 6.1%-7.5%, respectively, and those for migration times were 3.4%-5.8% and 4.3%-6.3%, respectively. The presented method was successfully applied to the determination of EP in EP injection and urine samples of smokers and nonsmokers. The recovery test results for urine samples ranged from 86.5 to 112.0%, which demonstrated the reliability of this method. The results for urine sample detection indicate that the average level of EP in the urines of the smoker group is obviously higher than that in the urines of the nonsmoker group, which may demonstrate that smoking can stimulate the release of EP in human body. (C) 2012 Elsevier B.V. All rights reserved.