Qualitative detection of formaldehyde in the hotte

Qualitative detection of formaldehyde in paints and decorative materials

qualitative detection of formaldehyde in paints and decorative materials

November 12, 2018

formaldehyde (HCHO) is a colorless, irritant and water-soluble gas It has the function of coagulating protein. Its 35% - 40% aqueous solution is called formalin, which is often used as a solution for impregnating specimens Formaldehyde is a highly toxic substance, ranking second on the priority control list of toxic chemicals in China The international agency for research on cancer (IARC) upgraded formaldehyde as a class I carcinogen in 2004 This conclusion is made by 26 scientists from 10 countries after evaluating the existing carcinogenic evidence of formaldehyde

the expert group believes that there is sufficient evidence to prove that formaldehyde can cause human nasopharyngeal carcinoma and nasal cancer, and it is clear that the export of rare earth implements the export license management of nasal sinus cancer, and there is evidence to prove that formaldehyde can cause leukemia Formaldehyde was listed as a class I carcinogen in the carcinogen report issued by the U.S. Department of health and public utilities QA and the Bureau of public health in 2006 Under certain conditions, the detected concentration of formaldehyde in indoor air can gather above the standard allowable level, and the release period is relatively long. The recycled plastic granulator, which is the main processing machine in Yokohama, Japan, will have a large customer base. University research shows that the release period of indoor formaldehyde is generally 3 to 15 years

1 the main source of formaldehyde in residents' homes comes from plywood for interior decoration. 2. It is necessary to equip ball screws for clearing and protection every six months, blockboard, medium density fiberboard, particleboard and other man-made boards Because formaldehyde not only has strong adhesion, but also can increase the hardness of materials, and has the functions of insect prevention and corrosion prevention, the adhesive used in the production of wood-based panels at present is urea formaldehyde resin with formaldehyde as the main component. The residual formaldehyde in the panel and the formaldehyde that does not participate in the reaction will gradually release to the surrounding environment, resulting in the formaldehyde content in the indoor air exceeding the standard

formaldehyde comes from furniture made of wood-based panels In order to pursue profits, some furniture manufacturers use unqualified plates, or the manufacturing process is not standardized, making furniture a formaldehyde emission station A comparative test conducted by the Beijing Consumer Association showed that among the 60 sets of medium density furniture sampled in Beijing, 29 sets of formaldehyde exceeded the relevant national standards, and the non-compliance rate was as high as 48 23% . Formaldehyde comes from decorative materials, such as white latex, foamed plastics, paints and coatings For example, free formaldehyde in some water-based adhesives exceeds the standard, and the actual formaldehyde content of some white latex exceeds the standard by nearly 5 times Latex adhesive is widely used in wood engineering and wall treatment in decoration, and the formaldehyde enclosed on the wall is difficult to remove

formaldehyde comes from indoor decorative textiles, beddings, wall cloths, wallpaper, chemical fiber carpets, curtains and cloth furniture In textile production, additives containing formaldehyde are often added to increase the wrinkle resistance, water resistance and fire resistance of textiles In July, 2004, the General Administration of quality supervision, inspection and Quarantine of the people's Republic of China (AQSIQ) conducted a random inspection of 149 kinds of bedding products, and the formaldehyde content of individual products was 50 times the standard limit National 5 limits on formaldehyde content of textiles 6 stipulates that the formaldehyde content of bedding and indoor articles (including cars, boats, planes) that directly contact the skin, such as sofa covers, bedspreads, wall cloths and so on, should be strictly controlled Formaldehyde comes from cosmetics, detergents, pesticides, disinfectants, preservatives, printing inks, paper, etc

with the improvement of human self-protection consciousness and the continuous progress of industrial technology, some industrial products containing formaldehyde are gradually replaced by environmental protection products China has also continuously issued corresponding standards to limit the content of formaldehyde in products, but because formaldehyde containing products are cheap and corrosion-resistant, they have been used by some enterprises or individuals who forget their interests and harm consumers For example, use water-soluble interior wall paint (containing 107 glue) with high formaldehyde content to pretend to be latex paint (environmental friendly, formaldehyde free), use formalin (40% formaldehyde aqueous solution) as preservative to treat aquatic products, and use industrial bleach hanging white block (sodium formaldehyde bisulfate) as brightener to treat wheat flour, etc These problems have aroused great concern of quality inspection departments at all levels in China In order to effectively protect the vital interests of consumers, we must take effective measures to strengthen the quality supervision and management of relevant products, and do a good job in the identification inspection and content determination of formaldehyde in water-soluble interior wall coatings and interior decoration materials

2 detection of formaldehyde the test principle of qualitative detection of formaldehyde is to use the principle that formaldehyde reacts with Chromotropic Acid in sulfuric acid solution to form purple compounds for inspection

2. 1 sample treatment

extraction of formaldehyde in paint: first weigh 2 g of evenly stirred sample, put it into a distillation flask with 50 ml of water, shake it well, then add 200 ml of water, and collect 100~200 ml of Distillate by atmospheric distillation method for standby

extraction of formaldehyde from decoration materials. The composite floor is cut into 300mm x 150 mm pieces, sealed around with formaldehyde free tape, put into a small beaker, add 20 ml of water, and put into a 40 l dryer Particleboard, plywood and blockboard are cut into 150 mm X50 mm blocks and installed on the iron frame

2. 2 qualitative test of formaldehyde

take 5 ml of the above formaldehyde extract and put it into a colorimetric tube, add 1 ml of sodium chromotropic acid solution and 4 ml of sulfuric acid, and heat it for 3-5 minutes. If the solution changes from colorless or light yellow to purple, it can be determined to contain formaldehyde

2. 3 Comparison between rapid method and arbitration method

the acetylacetone method for the determination of formaldehyde is classic and accurate, but acetylacetone needs to be re distilled, and the storage time of the prepared chromogenic agent is short. If you only need to know whether the sample contains formaldehyde, the chromotropic acid method is more convenient

the color developing agent of acetylacetone method is colorless or light yellow, but the color deepens after reacting with formaldehyde, while the color developing agent of chromotropic acid method changes obviously and is easy to observe

if it is necessary to further test the formaldehyde content in the sample, it is only necessary to extract the collected amount when the fraction is collected, and determine the formaldehyde content according to the corresponding test standard