| Naturally brown cotton is praised as green textile material,it need not to spray pesticides in the process of planting,which can reduce the pollution caused by chemical pesticides;and it does not have to be dyed or bleached during the processing,which not only can save the production costs,but also reduce the environmental pollution,thus it has a good market application value and development prospect.There are many varieties of brown cotton with different shades of color,such as dark and light brown cotton,etc.In addition,naturally brown cotton is easy to be counterfeited by dyed brown cotton.All these issues have brought challenges for the identification of naturally brown cotton.In view of the complexity of pigment components,It is essential to have a study on the distinction of pigment components in naturally brown cotton,which were collected from different varieties and treated by textile process sequences.This topic analyzed the pigment components of different varieties brown cotton,and the change of pigment components after treatment by textile process sequences,and then tried to construct the related HPLC fingerprint.The main results of this study are as follows:(1)Extracting the pigment of brown cotton under different ultrasonic conditions(time,temperature,solid-liquid ratio),and analyzing the extracts by High Performance Liquid Chromatography(HPLC).The results showed that ultrasonic extraction conditions had a significant influence on the strong polar components with the retention time of 0-5 min,especially the number and area of chromatographic peaks.Such as the components with retention time of 1.9 min could not be extracted in short time,low temperature and high solid-liquid ratio.When the temperature was lower than 45?,the components with retention time of 2.5 min could not be extracted,and the extract contents of components with retention time at 1.4 min,2.7 min and 3.5 min were less.Ultrasonic extraction conditions had a less influence on the components of retention time between 7-20 min,which showed that the extraction efficiency of the components were different under different extraction conditions.These results showed that ultrasonic conditions had a significant effect on the composition of extracted pigment components.According to the changes of area and number of peaks,the research optimized the ultrasonic conditions which could extract the most content of pigment components were 4 h,55?,1:50(g/m L).(2)Collecting the different origins and varieties of naturally brown cotton,and then explored the HPLC fingerprint of extracted-pigment,which founded that the pigment components in different varieties of naturally brown cotton were similar,however the contents of corresponding components were different in a centain degree,the more closer of the fiber colors were,the more similar of the pigment components were,and it had less relativity with origin.The HPLC chromatography of brown cotton pigments of different varieties were similar,the peaks of retention time between 7-20 min were basically similar,it could be identified as the characteristic peaks of brown cotton pigment.The HPLC chromatography of different light brown cotton pigment extracts was remarkably similar,there were 4 common peaks with retention times at 1.4 min,1.9 min,2.5 min and 7-20 min.Then acquired the highly related HPLC fingerprint of naturally light brown cotton.However,the HPLC chromatograms of dark brown and light brown cotton pigment extracts had a great difference,they could not construct a higher correlation HPLC fingerprint.(3)The HPLC peaks area of brown cotton pigment extracts were decreased inordinately after treatment by solarization,washing,high temperature and scouring,this showed that the stability of pigment components were different.The pigment components of retention time at 1.4 min,2.5 min,2.7 min,7-20 min were relatively stable,only appeared as the areas of the chromatographic peak were decreased to varying degrees.Among them,the components of retention time between 7-20 min can be used as HPLC characteristic peak of naturally brown cotton.However,the components of 1.9 min and 3.5 min were not very stable,and their peak area changes greatly.After brown cotton fiber were treatment by oxidation,there was only one peak of retention time at 2.5 min in HPLC chromatography of pigment extracts,it showed that the structure of most pigment components had changed,only the structure of component with retention time at 2.5 min was stable,it was hard to be oxidized.In addition,After brown cotton were treatment by solarization,washing,high temperature and scouring,the color of brown cotton fiber was still brown,but the color depth had changed.When the brown cotton were treatment by oxidation,its color almost faded,and the peak of retention time between 7-20 min was disappeared in HPLC chromatography.So we can draw a conclusion that components of retention time between 7-20 min were the main components of pigment,and these components played a more prominent role in color rendering of brown cotton.The HPLC chromatography of pigment were change larger after brown cotton treatment by solarization,washing,high temperature and scouring,thus they can not construct highly related HPLC fingerprint. |
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