Study on extraction and quantification of fiber pigment matter in colored cotton
彩色棉纤维色素提取和测定方法的研究

Pigment matter in mature fibers of brown or green cotton was extracted by organic solvent (ethanol, aether and dimethylbenzene), acid and alkaline solution, and HNO 3/ethanol. The comparison of three extraction methods showed that pigment matter in colored fiber cells could be effectively extracted out only by HNO 3/ ethanol distillation. There was a maximum absorbance peak at 412 nm for fiber pigment solutions from HNO 3/ ethanol distillation. Absorbance readings of sample solutions at this wavelength were associated with fiber color and its intensity, for brown or green fibers increased with fiber color deepening (0.063 4 0.990 0) and for white fibers only had a negligible quantity (0.007 2). Therefor, it was suggested that the HNO 3/ethanol distillation method for extraction and quantification of fiber pigment be in favor of comparison of the color intensity for colored cotton varieties. When brown or green fibers were treated with acid or alkaline solutions, fiber color not only changed with pH value and but also restored to original color at pH7. There was a negative relationship between pigment and cellulose content in colored fibers.