For those who have just bought a house, they have to go through the busy process of making appointments with interior designers from major decoration companies and visiting major building materials markets, furniture and home appliance stores.
Various uneasy feelings during this process, such as the work not being delivered as scheduled, the project quality not up to standard, decoration materials not up to standard, formaldehyde after decoration exceeding the standard, how to choose the testing agency, are intertwined and exhausting, in order to make you reduce A little tired, I suggest that you choose a professional testing agency (with CMA qualification) for formaldehyde testing.
Although handheld detectors, portable detectors, formaldehyde self-test box can all obtain certain data, the accuracy of the data is extremely poor and has no substantial reference significance.
The handheld detector measures particles by counting the particles within the range it comes into contact with. Since the particle size of formaldehyde molecules is much less than 2.5 microns and the smaller the molecules move under Brownian motion, the more irregular the movement, so by counting Accurately counting formaldehyde molecules is as difficult as the sky.
The biggest problem with portable detectors and self-test boxes is the color comparison card. The human eye can only identify colors with large color differences but cannot identify similar or similar colors. When a display agent is added to the air sample, the color displayed cannot be Accurately corresponds to the color chart. In addition, if the color range corresponding to a color comparison card is larger, the corresponding numerical range will also be larger.
The more reliable formaldehyde detection method is phenol reagent spectrophotometry .
The first step: Prepare the formaldehyde absorption solution
The second step: Use an atmospheric sampler to collect air samples
The third step: Sample color development
Add a certain amount of ferric ammonium sulfate solution to let the transparent formaldehyde The sample changes color.
| Step 4: data analysis
| Put the colored sample into the spectrophotometer , and test the absorbance of .
| Step 5: data processing
The absorbance is not the concentration of formaldehyde but the main influencing factor. Therefore, the formaldehyde concentration (mg/m⊃3;) can be obtained by adding the absorbance into the following formula for calculation.
Where: C——Formaldehyde concentration in the air, ㎎/m⊃3;
A——Absorbance of sample solution;
A0——Absorbance of reagent blank solution;
Bs——The standard curve obtained by drawing standard solution Calculation factor, ugh;
V0 - converted to sampling volume under standard conditions, L.
