Abstract: Flow injection analysis has now been extended to include measuring the hydrolysis of fiber reactive dyes on line during the dyeing process. An isocratic high performance liquid chromatography separation method was developed to separate heterobifunctional reactive dyes into monohydrolyzed, dihydrolyzed, and reactive components. The integrated FIA-HPLC system was used to monitor the percentage exhaustion and hydrolysis during dyeings with yellow and blue heterobifunctional reactive dyes, individually and in combination. Results from constant temperature dyeings at two different temperatures are given.

Abstract: Real-time monitoring of the exhaustion of water-soluble dyes has been extended to disperse dyeing of cellulose acetate and polyester. A previously described flow injection analysis system was modified to monitor disperse dyeings on a laboratory package dyeing machine. These equipment modifications, as well as the process for selecting an appropriate solvent, are presented. Calibration models for converting visible spectra to individual dye concentrations were developed using partial least squares regression. These models were validated with three-dye mixtures of known concentrations and then used to monitor disperse dyeing of cellulose acetate fabric and polyester yarns. Supercritical fluid extraction of disperse dye from the polyester yarn confirmed the concentrations as determined from real-time flow injection analysis.