基于酚醛反应显色原理的莨纱绸鉴别方法研究

Research on the identification method of gambiered Guangdong gauze based on the principle of phenolic reaction color development

为了高效地鉴别莨纱绸的真伪,根据芳香醛与薯莨色素发生酚醛缩合反应的机理,将香草醛、4-甲氧基肉桂醛和4-(二甲基氨基)肉桂醛配制成的鉴别试剂分别与薯莨色素溶液混合,观察溶液颜色变化并探究鉴别试剂与薯莨色素溶液的最佳反应条件。研究结果表明,3种芳香醛的混合溶液颜色均变深,其中4-(二甲基氨基)肉桂醛组颜色最深即反应最剧烈。最佳反应条件为:质量分数0.2%的4-(二甲基氨基)肉桂醛,pH值1.4,反应温度40℃,反应时间10 min。最后,将芳香醛鉴别试剂滴加到纯正莨纱绸表面,绸面颜色变深、K/S值增加,可用于莨纱绸的高效定性鉴别。

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 1045 cm-1 and 1428 cm-1 in vanillin group,2857 cm-1 and 2927 cm-1 in 4-methoxycinnamaldehyde group,and 1680 cm-1 in 4-(dimethylamino)cinnamaldehyde group,and all three groups generated new absorption peaks near 1724 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.