Chemometrics based mapping for stability pattern of azo food dyes sunset yellow and Ponceau 4R using validated HPLC-multi-wavelength method

Abstract

Azo food dyes degrade to sulphonated as well as non-sulphonated carcinogenic aromatic amines (NSAA) under accidental exposure of aggravated environmental conditions. The targeted chromatographic achievements of eight NSAA viz. aniline, 4-aminoazobenzene, azobenzene, 4-aminobiphenyl, sudan-1, 1-napthylamine 4-methylimidazole and p-toluidine in degradation and stability samples of Sunset yellow and Ponceau 4R were exercised using validated HPLC–PDA method. The chromatographic retention of selected peaks were successfully achieved on Hyper Sil gold C8 Stationary phase (250 mm × 4.6 mm i.d., 5 µm particle size) with ammonium acetate buffer (pH 4.0) as mobile phase A and combination of acetonitrile and methanol as organic phase (mobile phase B) in gradient mode. The optimised analytical method was specific, accurate & precise and detector signal was observed linear in the range of 50–10,000 ng.mL⁻¹ for all aromatic amines. The stability of selected azo dyes was observed for three months at refrigerated (2–8° C) and at room temperature (25 °C) both in solid state and in liquid state. The degradation and stability data were mapped to reveal the essential pattern of carcinogenic aromatic amines formation using unsupervised learning approaches to discriminate the NSAA formation under forced degradation conditions and stability of selected dye/s at various storage conditions. The heatmap and PCA reveal that the stability of selected azo dyes at room temperature and in refrigerated storage conditions could be correlated with formation of 4-aminoazobenzene, azobenzene, 4-aminobiphenyl, sudan-1, 1-napthylamine and p-toluidine. As per regulatory guidelines, aniline formation should be observed during storage period, as contrast to traditional consideration of aniline as major NSAA, whose occurrence is in-general calculated as total NSAA formation, it was not observed in any storage sample.

Graphical abstract