Abstract: Synthetic food dyes were separated by capillary zone electrophoresis using an alkaline phosphate buffer as background electrolyte. The precision had a relative standard deviation of less than 0.5 % for the run-to-run migration times and 2 % for the peak areas with buffer replenishment after each run. The detection limit for the individual dyes was about 1 ng using a 50-µm internal diameter Agilent extended path length capillary. Compounds were detected at different wavelengths— 215, 410, 520 and 598 nm—and the identities of the individual dyes were confirmed using peak-purity routines and a UV-visible spectral library.
This document details an analytical method for separating synthetic food dyes using capillary zone electrophoresis (CZE). The study utilizes an Agilent CE system with a built-in diode-array detector and ChemStation software to analyze various colorants found in food products. The method employs an alkaline phosphate buffer as the background electrolyte to achieve high precision in run-to-run migration times and peak areas.
The analysis covers a wide range of synthetic dyes, including azo and triarylmethane types, detecting them at specific wavelengths (215, 410, 520, and 598 nm). Identity confirmation is achieved through peak-purity routines and comparison against a UV-visible spectral library. The document provides experimental conditions, including buffer composition, temperature, voltage, and capillary specifications, along with results demonstrating the method's ability to separate and quantify multiple dyes in a single run.
| Capillary internal diameter | 50 µm |
|---|---|
| Capillary total length | 64.5 cm |
| Capillary effective length | 56 cm |
| Operating temperature | 30°C |
| Applied voltage | 30 kV |
| Detection wavelengths | 215, 410, 520 and 598 nm |
| Buffer composition | 10 mM sodium phosphate with 5 mM sodium hydrogen carbonate at pH 10.5 |
| Relative standard deviation (migration times) | less than 0.5 % |
| Relative standard deviation (peak areas) | 2 % |
| Detection limit | about 1 ng |
The dyes are detected at 215, 410, 520, and 598 nm.
Identities are confirmed using peak-purity routines and a UV-visible spectral library.
The relative standard deviation for run-to-run migration times is less than 0.5 %.