Spectrophotometric determination of cyclamate in artificial sweeteners and beverages after ultrasound-assisted emulsification microextraction

Abstract

A new method has been developed for the determination of cyclamate using an ultrasound-assisted emulsification microextraction (USAE-ME) procedure coupled with UV-Vis spectrophotometry. The method is based on the protonation of cyclamate ions in acidic medium and the extraction of the formed cyclamic acid into fine droplets of chloroform as an extraction solvent that contains rhodamine B (RhB) reagent. The extracted cyclamic acid can further react with RhB for the formation of a highly colored ion-pair complex of [cyclamate][RhBH⁺], which is used for the subsequent spectrophotometric determination of cyclamate. One variable at a time optimization and response surface methodology (RSM) based on central composite design were used to obtain optimum conditions for the microextraction procedure, and nearly the same experimental conditions were obtained using both the optimization methods. Under the optimum conditions the calibration graph was linear over the range of 50–900 ng mL⁻¹ (R² = 0.9994), and the limit of detection (S/N = 3) was estimated to be 10 ng mL⁻¹. The relative standard deviation for 200 ng mL⁻¹ of cyclamate was 2.3% (n = 5). The proposed method was successfully applied for the determination of cyclamate in beverages and sweetener tablets. The average recovery of spiked samples was 99.7%. The results demonstrated that the developed method is simple, rapid, inexpensive, accurate and remarkably free from interference effects.