This study analyzed synthetic dyes using ion-pair, reversed phase chromatography on a special base-deactivated HPLC column. This separation mechanism was chosen to reduce tailing effects of highly polar colors. Detection was performed using a new design of diode-array detector based on two lamps — a deuterium lamp and a tungsten lamp. This ensured highest light output at 190 – 950 nm, which resulted in lowest detection limits over the entire wavelength range. It was possible to analyze blue, black or green colors in the low ng range at their absorption maxima of 600 – 700 nm. Complete spectra, feasible from 190 – 950 nm, facilitated identification with an automated library search.
This document details a method for the sensitive analysis of synthetic dyes in food, pharmaceutical, and chemical processing applications. The study utilizes ion-pair reversed-phase chromatography on a special base-deactivated HPLC column to reduce tailing effects of highly polar colors. Detection is performed using a diode-array detector equipped with both deuterium and tungsten lamps, ensuring high light output and lowest detection limits across the 190 to 950 nm wavelength range. This dual-lamp design allows for the effective analysis of blue, black, and green colors which absorb at wavelengths where conventional single-lamp detectors perform poorly.
The document provides specific experimental conditions, including mobile phase compositions and gradient settings, for separating various synthetic colors such as Tartrazine, Amaranth, and Brilliant Blue. It demonstrates the system's capability to identify compounds using automated library searches based on complete spectral data, even at trace levels in the low ng range. The note also includes examples of analyzing synthetic colors in carbonated drinks and pharmaceutical preparations like capsules.
| Wavelength range | 190 - 950 nm |
|---|---|
| Column dimensions | 125 x 3mm |
| Column particle size | 3 µm |
| Flow rate | 0.8 ml/min |
| Column temperature | 40°C |
| Injection volume | 1 µl |
The detector covers a wavelength range from 190 to 950 nm.
The detector is equipped with a deuterium lamp and a tungsten lamp.
A 125 x 3mm Hypersil BDS, 3 µm column is recommended.