Research on the identification method of gambiered Guangdong gauze based on the principle of phenolic reaction color development
Gambiered Guangdong gauze is the only silk fabric in the world that is dyed with plants.In its processing,the silk fabric is repeatedly impregnated in Dioscorea cirrhosa Lour extract and exposed to the sun for dozens of times,and then coated with the pollution-free river mud in Guangdong province.After full reaction,the excessive river mud is washed away and dried.It takes four weeks to complete the production.Due to its pure handmade,long production cycle and limited annual production in Guangdong,the market price of gambiered Guangdong gauze is relatively high.At present,the printing and dyeing process of synthetic dyes has appeared in the market to imitate gambiered Guangdong gauze,in order to seek high profits,which has caused unnecessary economic losses to ordinary consumers and employees.However,there is a lack of objective and efficient methods of identifying Gambiered Guangdong gauze in the market.To identify the authenticity of Gambiered Guangdong gauze,reduce the economic losses of consumers and practitioners,and standardize the sales market of Gambiered Guangdong gauze,three kinds of aromatic aldehydes including vanillin,4-methoxycinnamaldehyde and 4-(dimethylamino)cinnamaldehyde were used to formulate an identification reagent to identify Gambiered Guangdong gauze.Firstly,the color change of the identification reagent was observed after its reaction with the Dioscorea cirrhosa Lour solution,and the mechanism of the color reaction was investigated by UV-absorption spectrum and infrared spectrum.Subsequently,based on the color and absorbance changes of the chromogenic reaction,the optimum reaction conditions for the identification reagent were explored.Finally,the reagent was added onto the surface of the authentic Gambiered Guangdong gauze,the color change of the silk surface was observed and the K/S of the silk surface was measured.In this paper,the developed identification reagent was applied to the authentification identification of Gambiered Guangdong gauze.Combined with the color of silk surface and the change of K/S,the authenticity identification of Gambiered Guangdong gauze was realized.The experimental results indicated that,after reacting with vanillin,4-methoxycinnamical,and 4-(dimethylamino)cinnamaldehyde identification reagents,the color of Dioscorea cirrhosa Lour pigment changed to pink,magenta,and black,respectively.New peaks were generated in the UV-Vis at 500 nm,510 nm,and 640 nm,respectively.In the FTIR,new absorption peaks were generated at 1 045 cm-1 and 1 428 cm-1 in vanillin group,2 857 cm-1 and 2 927 cm-1 in 4-methoxycinnamaldehyde group,and 1 680 cm-1 in 4-(dimethylamino)cinnamaldehyde group,and all three groups generated new absorption peaks near 1 724 cm-1.The analysis of UV-Vis and FTIR of the reaction products showed that the phenolic condensation reaction occurred between aromatic aldehyde identification reagents and Dioscorea cirrhosa Lour pigment,which changed the color structure of the pigment.The optimal reaction conditions for identification reagent are follows:a mass fraction of 0.2％,a pH value of 1.4,a reaction temperature of 40 ℃,and a reaction time of 10 minutes.Based on the optimal reaction conditions,the identification reagent was added to the surface of the authentic Gambiered Guangdong gauze,the color of the authentic silk surface was darker,and the K/S increased from 5.13 to 6.68.The color of the genuine Gambiered Guangdong gauze became lighter,and the K/S decreased from 6.26 to 5.33.The method of this article can be used to identify the authenticity of Gambiered Guangdong gauze by identifying the color changes after reacting with reagents,which proves the validity of the method.
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