Study on Extraction Method and Spectral Properties of Pigment in Naturally Colored Cotton Fibers

Pigment in the mature fiber of green fiber and brown fiber defatted with the petroleum ether was extracted by five kinds of neutral solution (chloroform,ethyl acetate,ethyl acetate–ethanol(1:1), ethanol and distilled water). The result showed that the extraction of pigment in natural green fiber by using ethyl acetate–ethanol (1:1), while that in natural brown fiber by using distilled water was the most effective, respectively. The UV spectrum characteristic of the pigment of natural colored cotton was analyzed. There were three Absorbance peaks for green pigment at 252 nm, 300 nm and 328 nm, respectively. There was a linear relationship between the Absorbance value and its relative concentration at 300 nm or 328 nm. The brown pigment from distilled water distillation had a maximum Absorbance peak at 237 nm, but the spectrum of Absorbance peak moved to shortwave with the pigment concentration’s declined.