Analysis Of Textile Banned Azo Dyes Detection Method

With the release of EU banned azo dye regulations and China's mandatory national standard GB18401-2003 Textile production More and more attention has been paid to the detection of azo dyes. The banned azo dyes on textiles have become the most important monitoring indicators in the international and domestic production and trade of textiles and garments.

　　 National Textile Standardization Technical Committee On the basis of summing up the experience accumulated by many domestic experts in many years of testing work and referring to the EU standards, the basic branch organization standard drafting group completed the revision work of GB/T17592.1~17592.3-1998 series "national standard for testing prohibited azo dyes in textiles" in 2005. The revised version of GB/T17592-2006, "determination of prohibited azo dyes in textiles", was released and implemented in 2006. In order to ensure the accurate implementation of standards, the inspection institutions exchange experiences in different forms, and enterprises are also learning and consulting the relevant contents of the standards. Following discussions with relevant experts, the following issues related to GB/T17592-2006 are explained as follows:

1. major changes in the new standards

Compared with the 98 edition, GB/T 17592-2006 has the following main changes:

The original 3 parts are merged into 1 separate standards, and the standard names are revised.

The standard applies to textile products processed by printing and dyeing.

The species of aromatic amines increased from 20 to 24 species.

- liquid-liquid extraction has been cancelled, and the pretreatment procedure for the sample of polyester products has been increased.

- HPLC/DAD external standard method and GC/MS internal standard method were added.

- the addition of hydrochloric acid into the reaction solution by adding alkali and ether extract.

2. standard applicable product range

The 98 edition of the standard applies to "textile products suitable for cotton, wool, linen, silk and viscose fiber". In fact, in addition to natural fiber and viscose fiber, there are a large number of synthetic fiber products. Due to the narrow application scope of the original standard, there is no basis for detecting azo dye content of these products. Therefore, the scope of GB/T 17592-2006 clearly stipulates "textile products suitable for dyeing and finishing". Textile products processed by printing and dyeing are products that are dyed or printed with various coloring agents, including dyes (dyes), paints or pigments (pigments).

3. sampling and testing of products

GB/T17592-2006 stipulates that the test sample is "representative sample", which is in line with international practice. There is no sampling requirement in most of ISO's analytical standards for textile chemical analysis (e.g. formaldehyde and pH value). The analysis may be due to the variety and variety of textile products and the failure to adopt a unified rule.

For disabled azo dye Because of the different sampling methods, it may lead to different test results, which may cause omission or misjudgement. Therefore, it is necessary to clarify the sampling method. Here, sampling and testing of products are referred to "fifth GB 18401-2003 guide to textile classification and sampling", "textile standards and quality" 2006. For products of a single color, mixed color or similar effect, there is no special requirement for the sampling of the test; for each of the components of the textile product consisting of different components of fiber or color, it is detected separately.

Products with flower pattern (including printing and dyed fabrics) do not detect any color block as an independent component in principle. They are usually sampled according to the following methods:

For regular flower patterns, take at least one circular pattern or several circular patterns.

For larger or irregular patterns, sample as much as possible in proportion to the hue of the main body.

For local printing, independent printing and dispersed pattern of white land, sampling should include the color of the main body in the pattern. When the pattern is very small, it is not suitable to cut it from a number of samples and make it into a sample. If these local flowers or disperse colors are different, it is advisable to sample and test separately. If it is only a test of internal production control or quality analysis, it is another matter, and it can be detected separately by taking one pattern or one color.

4. pretreatment methods for polyester products

6.1 of GB/T 17592-2006 specified 2 different sample pre-treatment methods. The pretreatment method of 6.1.1 is to simulate the actual wearing and using conditions of textiles. Appendix B method is to extract dyes from fibers.

Different sample pretreatment methods will result in different results. Pure polyester products are processed according to appendix B. Other products are processed according to the method stipulated by 6.1.1, but this regulation is limited to domestic sales. For export products, they should be tested according to the regulations or standards of the exporting countries. For example, the products exported to European Union countries are best judged according to the description of the process or the experience of the operator, and then determine whether the dye should be extracted from the fiber and reduced by the appendix B.

5. limit the value of decomposable aromatic amines.

The determination limit of GB/T 17592-2006 is 5mg/kg. When the detection value is <5mg/kg, the report result is not detected; when the detection value is more than 5mg/kg, the actual test results are reported. However, it should be noted that the determination limit of GB/T 17592 is 5mg/kg, which is not equal to the limit value of decomposable aromatic amines banned by GB 18401. The limit value of decomposable aromatic amines on textile products is still 20mg/kg. When executing GB 18401, when the detection value is less than 20mg/kg, it is decided to meet the requirements; when the detection value is >20mg/kg, it is judged not to meet the requirements.

6. unprocessed products

In general, dyes and pigments will only be involved in dyed products. Banned azo dyes are also controlled against such non-ferrous products. However, it is also possible to detect decomposable aromatic amines in uncolored white or natural products, mostly due to other chemicals such as finishing agents, adhesives and so on. Therefore, the detection of prohibited azo dye items is generally prohibited for uncolored products. Even if the aromatic amine can be decomposed, the dye or pigment should be analyzed. If the product is not dyed or printed, the banned azo dye can be used.

7. Spandex Products

Products containing spandex will sometimes detect decomposable aromatic amines. The results should be analyzed to see whether they are the cause of the spandex itself or indeed the banned azo dyes or pigments. In general, if the decomposable aromatic amine containing spandex products exceeds the standard, the spandex can be removed and tested without any spandex. If the products without spandex are not detected, it can be judged that the decomposable aromatic amine of the product is caused by spandex and is not prohibited by azo dyes, and is indicated in the test report.