Study of Separation and Quantification of Structurally Analogous Reactive Dyes and Their Hydrolyzed Forms in Real Dyeing Process by Micellar Electrokinetic Chromatography

To optimize the dyeing process and minimize pollution, it is essential to develop rapid, real-time and accurate analytical techniques for detecting dye forms. Structurally similar reactive dyes, C.I. Reactive Orange 107 (RO107) and Yellow 201 (RY201), exhibit highly overlapping spectra, making the accurate identification and quantification of their six forms (original, activated and hydrolyzed forms for each) extremely challenging. This study aimed to address this issue by developing a novel capillary electrophoresis technique. The optimized background electrolyte consisted of 30.0 mmol/L Na2B4O7·10H2O and 45.0 mmol/L sodium cholate (SC), at pH 8.60 adjusted with 0.40 mol/L H3BO3. With UV detection, the limits of detection (LOD, S/N = 3) and quantification (LOQ, S/N = 10) for the six analytes ranged from 0.9 to 2.9 mg/L and 3.1-9.8 mg/L, respectively, with good linearity (R2 > 0.9965), migration time repeatability and intra-/inter-day peak area precision. The separation mechanism, based on micellar electrokinetic chromatography, utilizes SC micelles as pseudo-stationary phase to enhance migration differences via differential partitioning of analytes with varying hydrophilicity. Practical dyeing experiments demonstrated higher fixation rates for RY201 (25.57%, 29.85%) than for RO107 (17.42%, 18.01%) in both single and combination dyeing, confirming RO107's weaker adsorption capacity on the fabric.