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Textiles are very common in people's daily lives. Some daily necessities such as clothes, bedding and carpets are all textiles. However, the formaldehyde contained in textiles is harmful to the human body. Excessive formaldehyde can easily cause carcinogens to the human body. Therefore, it is very important to detect the formaldehyde content in textiles. Therefore, it is very important to detect the content of formaldehyde in textiles. The European Union, the United States, Japan and other countries have all listed formaldehyde in textiles in the monitoring range, and have made scientific and reasonable regulations on their specific limit values. This application note discusses the formaldehyde in textiles and its testing standard in detail, the content is for reference only.
Formaldehyde is a colorless, irritating gas with a strong odor. Its 35% to 40% aqueous solution is commonly known as formalin. Formaldehyde is a toxic substance of puree, which can combine with protein. Direct skin contact with formaldehyde can cause dermatitis, stains, and necrosis. After inhaling high concentration of formaldehyde, the human body will have serious respiratory irritation and edema. Frequent inhalation of a small amount of formaldehyde can cause chronic poisoning, mucosal congestion, skin irritation, allergic dermatitis, etc.
Since the 1920s, formaldehyde resin for textile has been used in fabric finishing, which is mainly used in post-finishing, such as anti-shrinkage, anti-wrinkle, waterproof, anti-fading, flame retardant treatment and so on. In addition, formaldehyde is added to auxiliaries in order to maintain the durability of printing and dyeing and improve the handfeel.
The testing of formaldehyde content in textiles is a work requiring high technical level. Acetylacetone colorimetry is a commonly used method to detect formaldehyde content in textiles. Since this method has been issued, after years of application, there has been a good response in all aspects, and the practicability is also very strong, but it is not perfect or there will be some problems, so we should pay more attention to the actual determination.
Calibration of formaldehyde solution
Which calibration method should be selected for the formaldehyde standard solution is the main problem to be solved now. The calibration of formaldehyde standard solution is more difficult. Most of the calibration methods used in various countries are iodometric method and pH titration, but it is very difficult to operate the procedure quickly and accurately. Therefore, the calibration problem of formaldehyde standard solution needs to be improved.
Selection of absorbance range of formaldehyde
When testing formaldehyde, if the absorption of the sample is too large or too small, it is likely to produce the deviation of Bill's law. Therefore, when measuring the absorbance of the test sample, we need to pay attention to the reasonable selection of the absorbance range, at the same time, we need to pay attention to the detection of the linear dynamic range of the absorbance of the instrument to ensure that the absorbance of the test sample and the instrument are within the reasonable range, and try to reduce the deviation of Bill's law, so as to strengthen the standard degree of the measurement results.
Experimental problems of dimethyl ketone
Relevant standards indicate that if there is doubt about the absorption and it is believed that it is caused by factors other than formaldehyde, then a confirmation test for dimedone is required. An insoluble condensate can be produced between dimethyl ketone and formaldehyde, which can be tested to find out why the absorption is affected; it is confirmed that the implementation of the test is decided by the relevant staff, The standard does not specify how to deal with the test results, but it is confirmed that the test results of the ketone are basically the following three types:
(1) If there is a change between dimethyl ketone and formaldehyde, and the absorbance has basically completely disappeared, then it can be confirmed that all the absorption is indeed from formaldehyde, and the original formaldehyde content result does not make any changes.
(2) If there is no change between the two and the absorbance still exists, then it can be confirmed that the absorption is due to other factors, and the original formaldehyde content result is changed.
(3) If there is a change between the two and the absorbance has not completely disappeared, it can be explained that part of the absorption is from formaldehyde, and the other part is from other factors. This is the formaldehyde content should be calculated according to the actual situation.
Operation problems of spectrophotometer
There are different types of spectrophotometer used in the laboratory. Different types play different functions, usages and precautions. Therefore, it is necessary for technicians to master the functions and usages of the spectrophotometer used, such as preheating and debugging of the instrument before use. The technical personnel shall periodically perform the operation verification on the wavelength according to the usage method on the spectrophotometer manual, so as to improve the accuracy of the test result.
Due to the lack of detailed regulations on the sampling of formaldehyde determination, there is no corresponding sampling criteria for the standard detection of products, which to a certain extent increases the difficulty of the laboratory staff, and also leads to unnecessary controversy.
Strengthen technical input and product development
Textile and clothing enterprises should timely understand and grasp the latest international textile printing & dyeing technology and information, and apply "green technology" to the production and processing of textiles and clothing, increase investment in science and technology, strive to develop non-toxic and biodegradable dyes and auxiliaries, adopt less pollution, pollution-free processes and treatment technologies, attach importance to the problem of harmful substance residues in clothing, actively develop ecological textiles that are beneficial to health and environmental protection, and provide consumers with "green clothing" that meets the requirements of safety and health.
Formaldehyde content determination is one of the most complex textile testing items, which involves the basic theory of chemical analysis and a variety of basic operating skills, which is difficult for the general test personnel who have not been trained in systematic chemical analysis. In addition, due to the lack of publicity and implementation of the standard, some problems existing in the standard (such as the calibration of formaldehyde standard solution) have not been properly solved. Formaldehyde content is a very important monitoring indicator. With the popularization of green consumption concepts and people's increasing attention, ecological textiles are becoming more and more mainstream in the market, which will promote the establishment and improvement of testing standards for formaldehyde content in textiles.
Alfa Chemistry Testing Lab is the world's leading third-party testing company, which can provide one-stop textile testing solutions for manufacturers and consumers.
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