Introduction

Food coloring compounds, both chemically synthesized and natural, are used to produce a desired color in a particular food. Among those food coloring compounds, some are approved for use as a food additive in certain quantities, while others are being evaluated for their affect on the consumer’s health.

As food coloring are just that, colors, they absorb light at very different wavelengths, thus a photodiode array is employed for this UHPLC analysis in powdered juice.

Experimental

Results

The chromatogram of a food coloring standard mixture and a contour plot are shown in figure 1. Good separation of nine ingredients was obtained within 2.5 minutes.

The on-peak spectra of the food coloring standard mixture are shown in figure 2. Good spectrum of each ingredient was obtained and the maximum absorbance wavelength for each is shown along with the maximum absorbance chromatogram below.

The chromatogram of the powdered juice and the contour plot are shown in figure 3, while the spectrum search results of each peak are shown in figure 4.

When the spectra of the standard mixture peaks in figure 2 were compared to those spectra in figure 3, a good correlation coefficient such as 0.990 ~ 1.000 was obtained for each peak shown in figure 4.