Analysis on the Detection Technology of Disabling Azo Dyes in Ecological Textiles

Analysis on the Detection Technology of Disabling Azo Dyes in Ecological Textiles

Cui Yanjuan, Lai Jinhu, Wang Zhichang

Abstract This paper analyzes and compares the pretreatment methods and detection methods of azo dye samples, and proposes a method to develop high-throughput, sensitive, fast, special-effect, non-destructive inspection of textile products, which has certain certain innovations in textile export detection technology. Guiding significance.

Key words eco-textile banned azo dye detection technology

1 analysis method for banned azo dye detection

1.1 Sample preparation technology

When the azo dye is disabled, the sample preparation method is the key. Whether the pretreatment is reasonable or not directly relates to the accuracy of the test results, which lays a foundation for the subsequent qualitative and quantitative analysis. Therefore, the decolorization, reduction, extraction and separation of the dye samples are discussed and studied. It is very important to effectively improve the pretreatment method of carcinogenic aromatic amines [1]. Before the standard method was not published in Germany, the relevant scientific research departments have carried out a lot of research, forming an early pretreatment method, mainly including decolorization, reduction and extraction, dissolution, direct reduction, etc. These three methods are to some extent There is a disadvantage that the dye of the reactive dye is difficult to be removed from the fabric, the reducing conditions are too intense, and other carcinogens are produced or the reduction is not complete.

1.2 Improvement study on sample pretreatment method

Most scholars pre-treat textiles with reference to the “Trial Test Method for the Prohibition of Azo Dyes in Textile Products” (the German Demonstration Method) or the pre-treatment method of the national standard published by the German Federal Institute of Consumers and Veterinary Medicine. The specific conditions are different, mainly reflected in the acidity and alkalinity of the decolorizing medium, the temperature of decolorization and reduction, the type of reducing agent, and the type of extract.

Chen Houyong [2] and others have studied the pretreatment method of the German inspection method, and considered that the method for pretreatment of colored textiles should belong to the classical constant chemical method. There are insufficient reagent materials, low work efficiency and long operation time. It is proposed to use micro-chemical method, and has been improved in many aspects. For example, by directly adding solid insurance powder to the reactor containing the sample solution instead of the 200 mg/mL powder solution used in the German test method, sodium dithionite is eliminated. Insufficient powder) is easily decomposed in air and water and has a satisfactory effect. After the textile sample is subjected to reduction and cleavage, the buffer is transferred to another tube, and 3 mL of t-butyl methyl ether is added to extract the residue. Transfer to a test tube containing buffer, extract for 1 min, repeat this 3 times, after standing or centrifuging, the organic phase is concentrated to about 2 mL for analysis, which is characterized by less solvent, saving time and effort, and It can effectively avoid systematic errors that may occur during solvent condensation. The recovery rate of each aromatic amine was above 80%. In a comparative study involving 13 testing institutions organized by the Hong Kong Government Laboratory, the results were in agreement with conventional methods.

Qian Yi [3] and others suggested using a weakly alkaline medium, decolorizing and reducing with 0.5 mol/L sodium carbonate at 95 ± 2 ° C, and with 1 mol / L sodium hydroxide solution, citrate buffer (pH = 6) Comparing the medium conditions, it is considered that the weak alkaline medium and the strong alkaline medium have the same effect, but the azo compound has not been sufficiently reduced under the weak acid buffer condition. The most important feature of alkali reduction is that the sodium hydroxide-sodium dithionite system effectively strips the dye and sufficiently reduces it.

Jiang Qi [4] used the powder-sodium hydroxide and stannous chloride hydrochloric acid system to decolorize and dye the dyed textiles, indicating: under strong reducing conditions (1mol/L sodium hydroxide-sodium dithionite system) Phenyl is the cause of the detection of 4-aminobiphenyl in non-banned dyes. This suggests that sodium dithionite as a reducing agent may not be suitable for the quantitative determination of aromatic amines in azo dyes. Catalytic reduction with Raney nickel at room temperature and neutral pH, but also 4-aminobiphenyl.

2 research methods of detection methods

There have been many reports on the detection methods of 20 carcinogenic aromatic amines. Currently, gas chromatography-mass spectrometry (GC-MS) is considered to be the best and most effective method for detecting aromatic amines. Due to the unique separation ability of the gas mixture by gas chromatography, the mass spectrometer is a highly sensitive and excellent qualitative analyzer that can determine the relative molecular mass, molecular formula and even structural formula of the compound, and requires fewer samples. However, generally only a single component can be given a good qualitative. By directly connecting the two instruments, the advantages of the two instruments are utilized to compensate for their respective deficiencies, and the detection sensitivity can be as high as 1 μg/L. The GC-MS method has obvious advantages in qualitative analysis, and it utilizes characteristic mass ion analysis technology. The establishment of a banned aromatic amine characteristic mass ion analysis method can quickly and accurately obtain qualitative conclusions with only a small amount of targeted analysis and judgment. The characteristic ion analysis method eliminates impurity interference, which not only improves the qualitative selectivity, but also can be used for quantitative determination.



The GC/MS combination method is also the method adopted by most domestic testing institutions. It can effectively separate 18 kinds of carcinogenic aromatic amines, and can quickly determine the relative molecular mass of the compounds, and provide information on the molecular formula and chemical structure of the compounds. However, when this method is used to disable the detection and analysis of azo dyes, the results are not completely reliable. This is because the method combines chromatographic retention time with mass spectrometry information to characterize, and the mass spectrometer can only provide fuzzy structural information of the analyte, which has greater limitations on the identification of isomers. In addition, the computer retrieval system compares the mass spectrum of the unknown component with the mass spectrum of the standard sample in the library, and gives a plurality of possible compound names arranged according to the degree of coincidence, usually the highest degree of agreement in the first place. The compound is the result of qualitative analysis, but in fact, the compound with the highest degree of agreement is often the accurate result, and it is very likely that it is ranked second, even the third and fourth are the correct results. In the computer automatic search for 18 aromatic amines, there are five aromatic amines in the search results. Therefore, the research on GC/MS in foreign countries has a decreasing trend, but it is still an effective qualitative and quantitative analysis method.

When the aromatic amine is usually detected by gas chromatography/mass spectrometry according to national standards, the isomers that may be present cannot be accurately detected, and the isomers can be determined by high performance liquid chromatography. Therefore, in addition to the analysis by gas chromatography/mass spectrometry, high performance liquid chromatography is required for verification analysis, which complements the detection and judgment in this aspect [5~7].

3 conclusions

The detection and analysis of azo dyes are prohibited, and the pretreatment of samples is the key. The current national standards in China have the disadvantages of cumbersome sample preparation, time consuming and laborious, which seriously restricts the high efficiency detection of textiles, the results and experiments of various detection methods. The conditions are closely related, and the use of one of the analytical methods alone cannot 100% confirm the presence of certain aromatic amines [5]. The combination of various chromatographic techniques and mass spectrometry broadens the detection method for banned azo dyes, improving detection efficiency and accuracy [6]. With the continuous development of ion source technology, the new ion source mass spectrometry has great significance in shortening sample pretreatment and realizing nondestructive testing of samples. Chen Huanwen [8] et al. studied electrospray ionization mass spectrometry for Sudan red dye in food. The rapid detection method successfully measured trace amounts of Sudan red dye in foods such as chili noodles and ketchup without sample pretreatment. With the continuous development of organic mass spectrometry and its application in environmental chemistry, medicine, petrochemical, food chemistry, toxicology, etc., research on non-destructive mass spectrometry detection methods for azo dyes and their metabolites in textile products and their production processes Will become a hot spot.

references

[1] Zhang Xiaoyi, Pan Yusheng. Electronic Structure and Biodegradation Activity of Azo Dye Molecules (1): Dual Charge Distribution[J].Chemical Journal of Chinese Universities,1998,19(8):1283~1287

[2] Chen Houyong, Mai Youding, Huang Zhiqiang, et al. Application of trace chemical treatment in the detection of textile banned azo dyes [J]. Modern Commodity Inspection Technology, 1997, 7(2): 7~9

[3] Qian Yi, Yan Yanping, Shen Zuhui, et al. Study on the detection method of banned azo dyes on dyed textiles [J]. Modern Commodity Inspection Technology, 1996, (3): 3~10

[4] Jiang Qi. Research on the detection method of banned azo dyes in textiles in Germany [J]. Silk, 1995, (10): 36~38

[5] Wang Wenjin. Increasing the accuracy of detection of banned azo dyes and the difference between international standards[J]. Chemical Fiber & Textile Technology, 2006, 9(3): 41~45

[6] Zhang Yan, Li Ying, et al. Separation and Determination of Banned Aromatic Amines on Cotton Fabrics by GC-MS[J].Chinese Journal of Spectroscopy Laboratory,2006,23(5):952~955

[7] Hu Xiaozhong, Yu Jianxin, et al. Identification method for banned false positive results in azo dye detection[J].Chinese Journal of Analytical Chemistry,2000,28(4):411~416

[8] Chen Huanwen, Zhang Wei, et al. Rapid detection of Sudan red dye in food by electrospray ionization mass spectrometry[J].Chinese Journal of Analytical Chemistry,2006,34(4):464~467





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