DETERMINATION OF FOOD SYNTHETIC DYES IN POWDERS FOR JELLY DESSERTS USING SLIT-SCANNING DENSITOMETRY AND IMAGE ANALYSIS METHODS

Abstract

A high-performance thin-layer chromatographic method combined with a sample preparation procedure has been developed for simultaneous determination of sunset yellow and azorubine synthetic dyes in powders for jelly desserts containing a variety of other ingredients. Some different extraction solvents and sample preparation steps (solid phase extraction procedures on RP-18 and polyamide cartridges) were tested for the quantitative isolation and purification of dyes. The best recovery results were achieved by using methanol for extraction procedure followed by solid phase extraction on the polyamide cartridges for the purification step. For the quantitative evaluation of the chromatographic spots, visible slit-scanning densitometry and digital processing of images of chromatographic plates (using ImageDecipher-TLC software with pure color-green and blue and integrate color- grey channels selection) were compared. The best statistical parameters for the linear functions of the calibration were obtained using ImageDecipher-TLC software for the quantitative evaluation of the investigated dyes. The lowest limits of detection and quantification (0.0096 and respectively 0.0190 µg/spot for azorubine and 0.0117 and respectively 0.0231 µg/spot for sunset yellow) were obtained by selecting pure color (green and blue) channels for dyes determination. The results obtained for commercial food samples showed that the proposed method is suitable for rapid routine analysis of synthetic dyes in powders for jelly dessert samples.

Keywords:

• digital processing of images
• food dyes
• HPTLC
• method validation
• quantitative evaluation
• sample preparation

Notes

*Data are mean of six identical sample applied as duplicates.

^a Data obtained by using slit scanning densitometer (at λ = 515 nm for azorubine and λ = 485 nm for sunset yellow).

^b Data obtained with ImageDecipher-TLC software by using integrate all color (grey) channel for analysis.

^c Data obtained with ImageDecipher-TLC software by using a pure color (green – for Azorubine and blue – for Sunset Yellow) channel for analysis.

*x = sample concentration; y = peak area.

(a) data obtained by using slit scanning densitometer (at λ = 515 nm for azorubine and λ = 485 nm for sunset yellow).

(b) data obtained with ImageDecipher-TLC software by using integrate all color (grey) channel for analysis.

(c) data obtained with ImageDecipher-TLC software by using a pure color (green – for Azorubine, or blue – for Sunset Yellow) channel for analysis.

^a Data obtained by using slit scanning densitometer (at λ = 515 nm for azorubine and λ = 485 nm for sunset yellow).

^b Data obtained with ImageDecipher-TLC software by using integrate all color (grey) channel for analysis.

^c Data obtained with ImageDecipher-TLC software by using a pure color (green – for Azorubine, or blue – for Sunset Yellow) channel for analysis.

^a Data obtained by using slit scanning densitometer (at λ = 515 nm for azorubine and λ = 485 nm for sunset yellow).

^b Data obtained with ImageDecipher-TLC software by using integrate all color (grey) channel for analysis.

^c Data obtained with ImageDecipher-TLC software by using a pure color (green – for Azorubine, or blue – for Sunset Yellow) channel for analysis.