Study On The Method Of Testing Cotton Fiber Sugar Content In Clothing

The sugar in raw cotton is composed of physiological sugar and insect honeydew. Physiological sugar Cotton fiber It is a kind of light loving plant. The cellulose in cotton fiber passes through photosynthesis, chlorophyll reducing glucose and other reducing sugar, enters into the cotton fiber cell, and then forms the disaccharide and the monosaccharide through the polymerization. It shows fructose, glucose and sucrose. Insect honeydew is a cotton plant with aphids, red bollworm and other insects. The insect's secretion adheres and dries up on cotton fibers after the boll opening. It is called exogenous sugar while cotton crops are eaten by insects. The wound mucus from the wound can not adhere to the cotton fibers after growing and spitting. It is mainly composed of trehalose, loose three sugar, fructose, sucrose and glucose.

The sugar content of cotton fiber has a direct impact on cotton quality and spinning process. The viscosity caused by high sugar content not only directly affects the processing speed and quality of cotton, including leather roller and sawtooth ginning, but also has great influence on the quality and efficiency of spinning. The excessive sugar content of cotton fiber will make it stick to the surface of textile machinery, affect the efficiency and reduce the textile performance. Cotton fiber is too high in sugar content and strong in viscosity, so it will bond to block and easily lead to the formation of easily broken cotton yarn. It may also aggregate and cause clogging of textile machinery and transportation pipelines. The occurrence of "three winding" phenomenon (around the roller, around the roller, and around the leather ring) will lead to production interruption. The research on the sugar content of cotton fiber has attracted widespread attention. Based on the analysis and comparison of the main testing methods of cotton fiber content at home and abroad, the future development trend of the determination method is put forward.

　 1 oxidation-reduction based on reducibility of ketones and aldehydes

Cotton fiber contains physiological sugar and insect honeydew. It can be divided into fructose, glucose, sucrose, trehalose, pine three sugar and so on. According to their characteristics, they can be divided into reducing sugar and non reducing sugar. Reducing sugars mostly contain reductive groups. If the sugar contains ketone (-R-CO-R '), glucose contains aldehyde group (-CHO). Because aldehydes and ketones are reducible, the sugar content in cotton fibers can be classified into two categories: reducing sugar test and non reducing sugar test.

1.1 reducing sugar test method

(1) Benedict qualitative method [4-5]. Benedict qualitative method utilizes the solution of chromogenic reagent containing two valence copper ions (Cu2+) to oxidate and react with the ketones and aldehydes contained in fructose and glucose in cotton fibers to form cuprous oxide precipitates and related complexes. Because of the different content of cuprous oxide, the solution shows different colors. The solution finally showed 5 colors, namely, sky blue, light grass green, green, yellow green and tea color. Because of the rapid deposition of cuprous oxide precipitates, the method has poor color stability and is suitable for qualitative research.

(2) Fhelin-Massat is a commonly used method of determining sugar content in the world. The complexes of Roche salt (C4O6H4KNa) and Cu2+ are formed. The reagent consists of two solutions: A (copper sulfate + methylene blue), solution B (sodium hydroxide + Rhodes + potassium ferrocyanide) and [7-8]. When the mixture of A and B two is mixed, copper sulfate precipitates with copper sulfate and sodium hydroxide. Roche salts react with precipitated copper hydroxide to form a soluble complex. Due to the indication characteristics of methylene blue, when the copper in solution is reduced, the methylene blue becomes colorless solution, indicating that the sugar content in cotton fiber can be calculated when the reaction reaches the end point. (3) DNS colorimetric qualitative method [7-10]. Similar to the Benedict method, Marsh et al. Produced a brown red amino -5 nitrosalicylic acid by the co reaction of 3,5- two hydroxysalicylic acid (DNS) and reducing sugar. In a certain range, the concentration of reducing sugar was proportional to the color intensity of the final 3- amino -5 nitro salicylic acid solution, and the sugar content in cotton fiber could be judged by colorimetry. However, Perkins[11] believes that the method is sensitive to the extraction of background color, decomposition of oxygen and color stability in samples.

(4) potassium ferricyanide quantitative method. The method of potassium ferricyanide is also called Perkins method. By using potassium ferricyanide (K3Fe[CN]6) and oxidizing reduction reaction of reducing sugar (fructose and glucose) in cotton fiber to produce potassium ferrocyanide (K4Fe[CN]6) solution, the potassium ferricyanide solution is used to titrate potassium ferricyanide solution in the presence of phenanthrene sulphate iron sulfate indicator. The terminal solution is changed from brown to yellow green, and the amount of potassium ferrocyanide is determined, because the amount of potassium ferrocyanide and the redox sugar content is proportional, so that the sugar content in raw cotton can be calculated. Because of the fact that non reducing sugar such as sucrose and pine three sugar can not be measured in cotton sugar, the non reducing sugar content is higher in aphid polluted cotton, accounting for 35% to 40% of total sugar content, while the content of whitefly pollute and unpolluted cotton is relatively small (about 20%), so the accuracy of this method used to measure whitefly pollution and unpolluted cotton is high, and the accuracy of cotton used to measure aphid pollution is greatly reduced.

(5) DNS visible spectrophotometer quantitative method. Fan Xuerong et al. Through the color rendering characteristics of the chromogenic agent 3,5- two hydroxysalicylic acid (DNS), through the redox reaction with the reducing sugar in cotton fiber, the brownish red 3- amino -5 nitro salicylic acid was produced. Then based on the linear relationship between the solution absorbance and the solution concentration in the Lambert-Beer law of spectrophotometric method, the concentration of reducing sugar was calculated according to the absorbance of the tested solution and the standard curve of movement. {page_break}

1.2 test method for non reducing sugar

Jiang Li and others will cotton The non reducing sugars were hydrolyzed into reducing sugar (fructose and glucose) by strong acid, then neutralized by equal amount of alkali, and then the sugar content in cotton was determined by Benedict. The total sugar content of cotton fiber can be calculated by this method.

　 2 detection method based on sugar aldehyde derivative method

The detection method based on the method of sugar derivatives is mainly due to the decomposition of sugars in the concentrated acid to form the glucuronic compounds. Due to the linear relationship between the content of sugar and the sugar content in cotton fibers, quantitative analysis can be made by spectrophotometry or UV spectrophotometry. The method is operable and is the mainstream method for testing sugar content in cotton fiber at present.

2.1 3,5- two hydroxytoluene sulfuric acid method. Sisman et al. Found that 3,5- two hydroxytoluene concentrated sulfuric acid can decompose monosaccharides and polysaccharides from cotton fibers into glycolaldehyde derivatives, forming a clear red complex. Depending on the concentration of sugar, the degree of coloration is from deep to shallow, and can be tested by spectrophotometer. China's trade standard SN/T 0311.1-94 "quantitative method for determination of sugar content in import and export cotton fibres" and National standard GB/T 16258-2008 cotton wool sugar content test method is also based on this principle.

2.2 alkenes UV method. Xu Zun and others made olefins, glucose and sucrose in oleic acid or alkaline solution to undergo olefin reaction. The concentration of hydroxymethylal content after the dehydration of concentrated acid is linearly related to the concentration of fructose, glucose and sucrose solution. By means of UV, the method of determining the total sugar content of cotton fiber is determined by mathematical calculation.

　 3 infrared spectroscopy

In recent years, infrared spectroscopy is based on the Perkins method, reducing the Cu2+ by reducing sugar in cotton fiber, and then measuring the absorption value of cotton fiber at a specific wavelength by infrared spectrometer, thus obtaining the absorption value of different sugar content. When the sugar content is abscissa and the absorption value is ordinate, the calibration curve will be given, and then the absorption value of the unknown sample at a specific wavelength will be measured. Zhang Huiyun and so on have similar studies in China. This method combines the advantages of Perkins method, is relatively simple and fast, but the machine cost is too high, which is not conducive to wide spread.

　 4 high performance liquid chromatography (HPLC)

High performance liquid chromatography (HPLC) can quantitatively calculate the total sugar content of cotton fibers by configuring the standard solution of all kinds of sugar contained in cotton fiber, and then extracting cotton fiber solution, and then measuring by HPLC. Gray and other high pressure liquid chromatography were used to determine the sugar content of cotton. He extracted water from cotton fibers by water extraction, and then used Spherisob S5NH separation column to show that the sugar content of cotton fiber was determined by differential refractive index detector. This method does not require derivatization of sugar in advance, and can be used to determine many kinds of sugars. Wang Kun et al. After two concentration of aqueous extract cotton fibers, the concentration of sugar and lactose, fiber two sugar, honey two sugar, pine sugar and other sugar standard solution were prepared by serial amino bond column. The total sugar content of cotton fiber was obtained by HPLC. This method is an efficient and accurate method for the determination of monosaccharides in cotton fiber. However, the test method is time-consuming and has some requirements for the conditions of the instrument, so it is not easy to promote.

5 testing methods based on biological enzyme

This method mainly uses the oxidation and dehydrogenation characteristics of biological enzymes to react with the glucose extracted from cotton fibers, so as to measure the actual content of glucose in cotton fibers. But this method is sensitive to glucose and can not be measured for other sugars.

5.1 glucose oxidase method. Using glucose oxidase to react with glucose in the extract, a gluconic acid peroxide is formed. Then hydrogen peroxide is reacted with a colorless dye to oxidize the dye to green. The brightness of the color is directly proportional to the amount of glucose that is initially present, so the amount of sugar can be determined by the brightness of the color.

5.2 delta glucose phosphate dehydrogenation method. After the aqueous extract of cotton fiber is made, the monosaccharide and disaccharide are converted into delta glucose phosphate under the action of enzyme preparation, and then nicotinamide adenine dinucleotide (NADPH) is formed under the action of delta glucose-6-phosphate dehydrogenase. NADPH can be measured by UV spectrophotometer at 960nm wavelength, because the sugar content in cotton fiber is proportional to the amount of NADPH, so that the sugar content of cotton fiber can be measured.

To sum up, we can see that the above methods have their own advantages and disadvantages. With the development of science and technology, the detection technology and means are constantly being introduced, and the testing methods of cotton fiber sugar content will also be developed in a fast, convenient, accurate and low cost way.