High-Resolution Mass Spectrometry Analysis of Reactive Dye Derivatives Removed from Biodegraded Dyed Cotton by Chemical and Enzymatic Methods

The purpose of this study was to determine and characterize the biodegradation of reactive dyes on cotton jersey fabrics buried in soil. Four commonly-used reactive dyes, C.I. Reactive Black 5 (RBlk5), C.I. Reactive Red 198 (RR198), C.I. Reactive Blue 49 (RB49), and C.I. Reactive Orange 35 (RO35), were used in this study. Degradation products were characterized and proposed based on high-performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (HRMS). A chemical method and an enzymatic digestion were developed and used to remove the reactive dye from the control and degraded cotton fabrics. Hydrolyzed reactive dyes and reactive dyes having cellobiose units were synthesized and used as standards for comparison in this study. The possible degradation mechanism pathways of the reactive dyes bonded to cotton fabrics depends on the chemical structure of each dye.