Testing Methods For Banned Azo Dyes In Textiles

With EU banned

The release of regulations and the implementation of compulsory national standards in China have attracted more and more attention. Banned azo dyes on textiles have become the most important monitoring indicators in the international and domestic production and trade of textiles and garments.

The standard drafting group of the National Association of textile Standardization Technical Committee organizes the standard drafting group. On the basis of summing up the experience accumulated by many domestic experts for many years in the testing work and referring to the EU standards, in order to ensure the accurate implementation of the standards, the testing institutions exchange experiences and experiences in different forms, and the enterprises are also learning and consulting the relevant contents of the standards.

Relevant experts discussed the following issues: the major changes in the new standards.

Compared with the Standard Version, the following changes have been made: the original 3 parts are merged into 1 separate standards, and the standard names have been revised; the standard is suitable for textile products processed by printing and dyeing; the liquid liquid extraction has been cancelled, the pretreatment procedures for the samples of polyester products have been increased; the HPLC/DAD external standard method and the GC/MS internal standard method have been added; the addition of hydrochloric acid into the alkali and ether extracts of the reaction fluid has been cancelled.

The standard applies to "cotton, wool, linen, silk and viscose fiber".

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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 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, paints or pigments.

Sampling and testing of products.

The test sample is specified as "representative sample", which is in line with international standards. There is no sampling requirement in most of the standards of textile chemical analysis methods (such as formaldehyde and pH value) of ISO.

The analysis of the reasons may be due to a wide variety of textile products, and it is impossible to adopt a unified rule.

For the detection of banned azo dyes, different sampling methods may lead to different test results, which may lead to missed detection or misjudgement. Therefore, it is necessary to clarify the sampling method.

Here, the product is tested and sampled.

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.

There are flower patterns (including

In principle, do not take any color block as an independent component for testing, generally sampling according to the following methods: for regular flower pattern, take at least one circular pattern or several circular patterns, cut and mix them; for larger or irregular patterns, sample as much as possible according to the proportion of the hue of the main body, cut and mix; as for local printing, independent printing and dispersed flower pattern, the sampling should include the color of the main body in the pattern, and when the pattern is very small, it is not suitable to be cut from multiple samples to form 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.