The release time of formaldehyde is quite long, up to more than ten years. Although the newly renovated house has been in addition to formaldehyde by various methods, it is impossible to completely remove formaldehyde in a short time. So, how to detect whether the indoor formaldehyde content is up to standard? This requires knowing: What are the formaldehyde detection methods? Professional methods and soil methods go into battle, and formaldehyde detection is not missed.
the chemical properties of formaldehyde are very active, so there are many quantitative analysis methods suitable for formaldehyde. Professional methods can be mainly classified into five categories: titration, gravimetric method, colorimetric method, gas chromatography and liquid chromatography. Among them, titration and gravimetric method are suitable for the quantitative analysis of high concentration formaldehyde, while colorimetry, gas chromatography and liquid chromatography are suitable for the quantitative analysis of trace formaldehyde. Here are two classic and effective methods.
1. Colorimetry
Colorimetry is a classic method to determine formaldehyde, and it is also a standard method to determine formaldehyde in the environment. Using UV-VIS analysis method has great advantages in analysis limit, accuracy and reproducibility. It's just a complicated operation.
Colorimetry can be divided into four methods according to different color developers: acetylacetone method, fuchsin sulfite method (Schiff reagent method), phloroglucinol method and chromotropic acid method.
2. chromatography
Because the formaldehyde molecule is too small, it peaks too quickly when it is directly analyzed by GC, and there is no response in FID detector; Liquid chromatography also flows out at the same time as the solvent peak because formaldehyde is too polar, and it cannot be detected without absorption in ultraviolet. Therefore, when formaldehyde is determined by chromatography, it is generally derived first, and then determined by GC or LC. 2,4-dinitrophenylhydrazine, as a relatively stable formaldehyde derivative, is widely used in the chromatographic determination of formaldehyde. The reaction formula between formaldehyde and 2,4-dinitrophenylhydrazine is as follows: < P > All reactions must be carried out under strong acidic conditions, and then the reaction products are extracted by organic solvent liquid or solid phase extraction. Because liquid-liquid extraction or solid-phase extraction not only increases the operation steps, but also causes the loss of derivatives. Usually, formaldehyde and 2,4-dinitrophenylhydrazine are directly reacted under weak acid conditions for liquid chromatography analysis, and organic solvent extraction is not needed, thus avoiding the loss in the extraction process. This method has been applied to the determination of formaldehyde in practical samples, with simple operation and accurate results.
The general methods, or earthwork rules, are as follows:
1. Check the reaction of animals and plants
If animals get sick after moving into a new house; Plants die and turn yellow, which indicates that the formaldehyde concentration in the new house may exceed the standard and needs to be paid attention to. If formaldehyde is found to exceed the standard, choose a major to go to the formaldehyde company for formaldehyde removal!
2. Self-testing method
Self-testing method refers to situations such as low immunity, decreased energy and easy fatigue after home decoration. Or feel a * * * smell, especially when you are close to a piece of furniture, you feel tears in your eyes. At this time, it is suggested to use more accurate detection methods to detect whether the indoor formaldehyde content exceeds the standard as soon as possible. If formaldehyde is found to exceed the standard, choose a major to go to the formaldehyde company for formaldehyde removal.
The soil method is to perceive the concentration of formaldehyde by one's own feelings, but it may have done harm to human body at this time. Therefore, before moving into a newly renovated house, it is better to use professional methods for testing first.