Simultaneous quantification of 5-hydroxyindoleacetic acid and 5-hydroxytryptamine by capillary electrophoresis with quantum dot and horseradish peroxidase enhanced chemiluminescence detection

•A new CE-CL method has been developed for the simultaneous determination of 5-HT and 5-HIAA.•The assay was successfully used for the determination of 5-HT and 5-HIAA contents in human urine.•The CE separation was accomplished within 10 min with the detection limits of 7.0 and 6.0 nM for 5-HT and 5-HIAA.•This method has not been reported, and can serve as an alternative tool for clinical assay of 5-HT and 5-HIAA.

A capillary electrophoresis (CE) with chemiluminescence (CL) detection method was developed for the simultaneous quantification of 5-hydroxyindoleacetic acid (5-HIAA) and 5-hydroxytryptamine (5-HT). In this method, CdTe quantum dot (QD) and horseradish peroxidase (HRP) were used as enhancing reagents to co-catalyze the post-column CL reaction between luminol and hydrogen peroxide, achieving highly efficient CL emission. 5-HIAA and 5-HT inhibit the CL emission resulting to the formation of negative peaks in electropherogram. The degree of CL suppression is proportional to the concentration of 5-HT and 5-HIAA. The linear ranges for the determination of 5-HIAA and 5-HT were 2.5 × 10−8–2.5 × 10−6 M and 2.5 × 10−8–5.0 × 10−6 M with detection limits (signal/noise = 3) of 7.0 × 10−9 M and 6.0 × 10−9 M, respectively. Intraday precision do not exceed 5.0%. The accuracy was confirmed by the recoveries ranged from 98% to 104%. The present method was successfully applied for the quantification of 5-HIAA and 5-HT in human urine. The concentrations of 5-HT and 5-HIAA in human urine were found to be in the range of 0.78–1.2 μM and 3.2–5.1 μM, respectively.