Determination of nicotine and its metabolite cotinine in urine and cigarette samples by capillary electrophoresis coupled with electrochemiluminescence

In this paper, CE coupled with electrochemiluminesence (ECL) detection using a 76‐μm Pt disk as working electrode was developed for nicotine (NIC) determination. The major metabolite of NIC is cotinine (COT), which has a similar tertiary amine structure to NIC. However, there is a carbonyl group attached in the structure of COT, which leads to the great decrease in ECL response. In order to improve the ECL response of COT, NaBH 4 was used for carbonyl reduction. After reduction, NIC and COT were separated and detected by CE‐ECL. ECL response plotted with NIC concentration was linear between 5.0×10 −7 and 5.0×10 −5  mol/L (81–8100 μg/L), with LOD of 5.0×10 −8  mol/L (8.1 μg/L). The developed CE‐ECL method was applied for NIC determination in urine and cigarette samples.