A sensitive,simple and low-cost method based on capillary electrophoresis(CE) with electrochemical(EC) detection at a carbon fiber microdisk electrode(CFE) was developed for the determination of nicotine.Effects of detection potential,concentration and pH value of the phosphate buffer,and injection time as well as separation voltage were investigated.Under the optimized conditions:a detection potential of 1.20 V,40 mmol/L phosphate buffer(pH 2.0),a sample injection time of 10 s at 10 kV and a separation voltage of 16 kV,the linear range obtained was from 5.0×10-7 mol/L to 1.0×10-4 mol/L with a correlation coefficient of 0.9989 and the limit of detection(LOD,S/N=3) obtained was 5.0×10-8 mol/L.The method was also used to determine the nicotine in cigarettes.Nicotine amount ranged from 0.211 mg/g to 0.583 mg/g in the pipe tobacco of seven brands of cigarette and the amount in one cigarette varied from 0.136 mg/cigarette to 0.428 mg/cigarette.
A facile approach for the synthesis of gold nanoparticle-loaded carbon nanofiber(Au/CNF) composites was developed. When applied to electrochemistry, these composites showed attractive performances such as high conductivity and facile electron transfer kinetics. Under physiological conditions, the Au/CNF composite modified electrode exhibits highly electrocatalytic activity for the oxidation of dopamine, ascorbic acid and uric acid. Owing to the good selectivity for the simultaneous detection of these three species, the novel composites are promising for the development of effective electrochemical biosensors.
The antidepressant trimipramine(Tri) enantiomers were successfully separated by capillary electrophoresis(CE) coupled with electrochemiluminescence(ECL) detection in aqueous-organic media. A dual cyclodextrin(CD) system combining β-CD and hydroxypropyl-β-cyclodextrin(HP-β-CD) was used as chiral selector. Acetonitrile(ACN) was added to the running buffer to improve the separation efficiency, detection sensitivity and repeatability. The method was also successfully applied to the chiral separation of Tri in spiked human urine sample.
