Capillary electrophoresis method for simultaneous analysis of caffeine, vanillin and ethyl vanillin in beverages

Abstract

Fast and simple capillary electrophoresis method was proposed for the simultaneous determination of caffeine, vanillin, and ethyl vanillin in beverages. The optimal separation conditions were 25 mM phosphate buffer at pH 8.5, containing 10% (v/v) acetonitrile and UV-absorption detection at the wavelength of 200 nm. Employing the optimum conditions, the three compounds were separated in less than 3 min. The procedure was validated with respect to linearity, limits of detection, limits of quantitation, (RSD%) accuracy (recovery), and precision (repeatability). Calibration curves with (r 2 > 0.9986) in the concentration range of 5-80 μg/mL were obtained for the three analytes. The limits of detection and quantitation in the range of 2.6-4.3 and 4.1-5.2 μg/mL were obtained, respectively. Recoveries of analytes in range from 92.1 to 104.4%, (n = 3) were attained.The validated method was successfully utilized for the analysis of the analytes in beverage samples.

An improved dual-channel capacitively coupled contactless conductivity detector with high detection performance

“…For sample detection, a constant-flow pump (Baoding Qili Constant Flow Pump Co., Ltd) was used to add the analyte and background solution to the two channels separately. When the two output signals were received by the lock-in amplifier and the differential signal input was selected, the entire detection set-up at this time constituted DFMIC 4 The multifunctional conductivity meter (DDS -608) was purchased from Chengdu Century Ark Technology Co., Ltd. The conductivity cell constant was 0.01 cm −1 , which was used to detect low conductivity solutions.…”

“…Secondly, we compared the responses of three detectors (C 4 D, DIC 4 In order to compare the detection performances of the three detectors over the entire concentration range, as shown in Fig. 4C and D…”

“…Secondly, we develop MIC 4 D based on differential detection to reduce the high baseline level and interference during experiments. Finally, DFMIC 4 D is successfully applied to the detection of low-conductivity solutions and different kinds of water, demonstrating the excellent performance of the detector.…”

“…Conductivity detection is commonly used in capillary electrophoresis (CE) and ion chromatography (IC), playing an important role in ion detection. [1][2][3][4][5] Compared with detection methods such as laser induced fluorescence (LIF) and ultraviolet absorbance (UV), it has more potential for allowing the miniaturization of instruments. [6][7][8][9] Conductivity detection can be performed in contact and contactless modes.…”

“…20 Standard diameter capillary tubes can be used, and the electrode arrangement has a higher degree of freedom. 16,21 In addition, as a non-invasive on-column detection method, C 4 D can be combined with other detectors for synchronous measurements to obtain more material information; [22][23][24] therefore, C 4 D has widely interested researchers since it was proposed.…”