Study on analytical scheme for human ecological quality control of chromium-complex acid dyes

Abstract

Analytical method for determining free chromium in chromium-complex acid dye where Cr is chelated to dye molecules is developed by their solid phase separation using C-18 column. Total Cr was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) on digested dye samples without the solid phase separation. Aqueous clear solutions extracted from C-18 columns, on the top of which each dye sample dissolved in methanol was loaded, were subjected to ICP-OES measurements for free Cr and to ion chromatographic measurements for Cr(VI), respectively. The deep-dyed nylon fabrics were subjected to the test of extractable Cr with artificial sweat solution. For eight commercial monosulfonated strongly polar Cr-complex acid dyes, total Cr and free Cr in dye products were estimated to be 15,271 mg/kg to 45,677 mg/kg and 193 mg/kg to 4048 mg/kg, respectively, while free Cr(VI) were measured to be 2.35 mg/kg to 16.2 mg/kg. Extractable Cr in their dyed nylon fabrics were measured in the range of 0.28 to 3.95 mg/kg. A proportional relationship between free Cr in dyes and extractable Cr in dyed nylons was observed. The analytical scheme using the solid phase separation using C-18 column is suggested for future quality control of Cr-complex acid dye products so that consequent dyed textiles do not fail in satisfying the globally- recognized human ecological criteria.