Rapid determination of cyclamate in foods by capillary zone electrophoresis with indirect ultraviolet detection

Abstract

A new method for the rapid determination of cyclamate in foods by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was developed. The separation was carried out with an uncoated fused-silica capillary (75 microm i.d., total length 80 cm, effective length 70 cm). The separation buffer consisted of 2 mmol/L sodium benzoate, 10 mmol/L sodium carbonate and 0.5 mmol/L hexadecyl trimethyl ammonium bromide. The separation voltage was -30 kV and the detection wavelength was 200 nm. The liquid samples could be directly injected after dilution with ultrapure water. The solid samples were first grounded or cut into pieces, and then extracted with ultrapure water. Then, the mixed solution was centrifuged. The supernatant was directly injected or injected after dilution with ultrapure water. The analytes were determined by external calibration. The limits of detection (S/N = 3) and the limits of quantification (S/N = 9) were 8.9 mg/kg and 26.7 mg/kg, respectively. The linear range between the corrected peak area and the mass concentration was from 1.2 mg/L to 80 mg/L with the correlation coefficient of 0.999 9. The average spiked recoveries of five replicates at three spiked levels (2.5, 10 and 20 mg/L) were 93.4%, 100.3% and 101.9% with the relative standard deviations of 6.7%, 2.0% and 2.2%, respectively. The intra- and inter-day precisions of the method were 2.6% and 4.5%, respectively. The method is simple and rapid with minimal sample pretreatment and reagent consumption. No solvent was needed throughout the whole process of analysis. The analysis could be completed within 11 min (6 min for rinsing and 5 min for separation). The newly established method was used for the determination of cyclamate in a proficiency test sample. The results were in good agreement with that of the National Standard method, which illustrated the accuracy of the present method. Then, seven food samples were analyzed using the current new method and satisfactory results were obtained.