A Rapid Qualitative Screening Method Based on Diazotization-Coupling Color Reaction for Determination of Banned Azo Dyes in Textile

Based on the principle of diazotization-coupling color reaction of aromatic amines, a rapid qualitative screening method for detecting 24 banned aromatic amines dyes in textile was developed. After reduction reaction, sample solutions were extracted with 10 mL t-butyl methyl ether and 5 mL hydrochloric acid respectively. Then 0. 05 mL sodium nitrite was mixed into extract liquids and maintained for 10 min. To get rid of redundant sodium nitrite, 0. 5 mL Ammonium sulfamate was added in. Thereafter 1 mL of guaiacol was added as color reagent. According to the condition of presence or absence of color. reaction, preliminary judgment of whether the textiles containing banned azo dyes could be done. The results showed that the detection limit of the method was less than 15 mg/kg. It met the requirements of the current regulation limits. The test results of more than 1000 actual sample showed that there was no false negative case of this method and false positive rate was 28%. Comparing with current testing means, this method could shorten the pre-processing time more than 60%, and saved reagent costs more than 90%. The whole test procedure could be processed without any chromatographic equipment.