Unified chromatography - Mass spectrometry as a versatile tool for determination of food dyes

Unified chromatography with mass spectrometric detection was assessed for determination of food dyes. Nineteen substances representing azo, triphenylmethane, xanthone, indigoid, quinoline and polyene classes covering an unprecedented range from nonpolar beta-Carotene (logD 13.6) to ionic Tartrazine (logD-7.5) were analyzed simultaneously. The dyes were separated in a single experimental run by an 18-min gradient elution from 98% CO2 to 100% aqueous-methanolic modifier on a diol column. Isomeric substances were resolved, and Isatin Sulfonic acid was detected as a degradation product of Indigo Carmine. Mobile phase properties reproducibly changed from supercritical to liquid state ensuring stable retention times (inter-day RSD<0.5%). Quantitative analysis of sports drinks after straightforward 10- or 25-fold dilution with dimethyl sulfoxide confirmed the method applicability to real-life samples. Suffi-cient limits of detection (typically 0.025 mg L-1 in processed samples, equivalent to 0.25 mg L-1 in drink) and a wide linear range (typically 0.5-50 mg L-1 or 1.3-125 mg L-1 in drink for 10x or 25x dilution, respectively) were demonstrated during validation. A comparison of method performance with competitive liquid chromatography procedures is also provided. Unified chromatography is a promising tool for comprehensive multiclass analysis of dyes in the context of food safety. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Unified chromatography with mass spectrometric detection was used to analyze a wide range of food dyes, demonstrating its potential for comprehensive multiclass analysis. The method showed stable retention times, sufficient limits of detection, and a wide linear range, making it suitable for real-life sample analysis and ensuring food safety. Comparisons with other liquid chromatography procedures highlighted the promising performance of unified chromatography in this field.