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How to detect whether formaldehyde exceeds the standard

How to detect whether formaldehyde exceeds the standard

Four seas network: formaldehyde has become the focus of people's attention in recent years, the harm of formaldehyde is self-evident, in the newly decorated house, formaldehyde content is the most, many friends are very like to know how to find out whether the formaldehyde in the home exceeds the standard, the following editor will teach you the tips to detect whether the formaldehyde exceeds the standard, hope to help you!

How to measure formaldehyde in the home to exceed the standard?

1. Every morning when I get up, I feel suffocated, nauseous, even dizzy.

2. There are often people at home who have cold, allergy and other problems, and they are in groups. Children often cough, sneeze and have decreased immunity.

3. Although I don't smoke, I often feel uncomfortable in my throat, foreign body and poor breath. When I go to work, I feel sore throat and dry respiratory tract. I'll be OK after work.

4. The family has a common disease, and after leaving this environment, the symptoms have obvious changes and improvement; the newly married couple are not pregnant for a long time, and can not find out the cause; the pregnant women find the fetal malformation under the condition of normal pregnancy.

5. In the newly moved or newly decorated house, the indoor plants are not easy to survive, and the leaves are easy to turn yellow and wither; after the new move, the domestic cats, dogs and even tropical fish die inexplicably.

6. The newly decorated family and office rooms or newly purchased furniture have pungent, dazzling and other irritating peculiar smell, and the peculiar smell does not disperse for a long time. Editor's summary: after learning the basic skills of how to detect formaldehyde, editor should remind you that when you feel uncomfortable in the newly decorated room or the air quality is not good, carry out professional inspection and pay attention to air ventilation. If the formaldehyde in the indoor environment has exceeded the standard, it should be treated in time.

Formaldehyde test method

The determination methods of formaldehyde include Phenol Reagent Colorimetry, acetylacetone colorimetry, chromotropic acid colorimetry, rapid detection and other chemical methods. The instrumental methods include high performance liquid chromatography, gas chromatography and electrochemistry. China's indoor air quality standard specifies colorimetry, Phenol Reagent Colorimetry and gas chromatography as the standard methods for the determination of formaldehyde in indoor air.

1. Colorimetry

Formaldehyde in the air is absorbed by the absorption solution and reacts with 4-amino group in the alkaline solution. The harm is oxidized by potassium periodate to form a purplish red compound. The color depth is directly proportional to the formaldehyde content. The formaldehyde content is determined quantitatively by colorimetry.

Determination range: if the sample volume is 20L, the concentration range is 0.01-0.16mg/m3.

Detection limit: 0.13ug.

2. Formaldehyde rapid test paper

The reaction part of the front end of the test paper is yellow. When the reaction part of the test paper is yellow, it is darker. It means that the indoor formaldehyde concentration is relatively high; when the reaction part of the test paper is light yellow, it means that the indoor formaldehyde concentration is relatively low. For details, refer to the standard colorimetric card, read out the general value, and determine whether the indoor formaldehyde concentration exceeds the standard or the general range.

3. Gas phase method

Formaldehyde in the air should be adsorbed on the dinitrobenzene coated support under acid condition to form stable formaldehyde hydrazone. After elution with carbon disulfide, it was separated by OV column and determined by hydrogen flame ionization detector. The retention time was qualitative and the peak height was quantitative.

Measurement range: if 20L is sampled with 0.1l/min flow, the measurement range is 0.02-1mg/m3.

Detection limit: 0.01mg/m3.

4. Formaldehyde rapid detection kit

Formaldehyde illegally added to food (formalin) can react with the reagent to produce purple product, and the depth of purple is directly proportional to the residual formaldehyde in the sample. Therefore, if the sample solution of aquatic products and aquatic foods is added into the reagent, and the color of purple is obvious after reaction, it indicates that the sample may have been soaked in formalin.

Test method: first add 1 drop of test solution a and 1 drop of test solution B to the hole of 'porous colorimetric tube'. Then, use 0.5ml pipette to absorb 0.5ml of sample exudate or soak solution (about 10 drops) and add it to the hole. Shake and mix it well (it is better to mix it well). After mixing well, add 1 drop of test solution C after about 1 minute. Observe the color change and judge the result with reference to the color card.

How to use formaldehyde self test box

The basic steps of formaldehyde detection box are as follows:

1. Before the test, please close the doors and windows of the room to be tested for 1 or 2 hours (different product requirements are different). When the room is closed, please close the air conditioning equipment such as air conditioner and purifier at the same time. If necessary, open the suspected pollutants such as furniture cabinet doors and drawers. (if it has been a closed space before the test, it is recommended to ventilate it for a period of time before closing it).

2. Pour the diluent liquid in the formaldehyde self-test box into the absorption box.

3. Place the absorption box at the pre selected position to be tested, and expose it for 30-40 minutes.

4. Pour the developer liquid into the absorption box completely, and cover the box cover; pay attention to the place where the light cannot reach, and avoid the interference of ultraviolet radiation affecting the accuracy of the result.

5. Observe the color after 10 minutes, compare it with the colorimetric card, and read the test results; pay attention to observe in the place where the light can not be irradiated to avoid the influence of ultraviolet.

It is recommended to carry out post closure test according to the required time. First of all, formaldehyde detection products are based on scientific principles and test data validation. In order to ensure the effectiveness of the detection results, the reasonable time of sealing before detection is specially specified. Secondly, we test formaldehyde to know the real concentration of indoor formaldehyde clearly. If the closing time exceeds the required time, the test result may be higher than the actual pollution situation, which is not convenient for us to judge.

Many consumers who have used formaldehyde self-test box have encountered this problem. Experts suggest that they pay attention to the following two points when comparing colors:

First, when comparing the color with the colorimetric card, the place with darker light should be selected, which can't be read under the sunlight, because the ultraviolet will cause the color to turn blue! The color can't be matched, which will seriously affect the test results.

Second, when comparing with the color comparison card, the results of the same color may be judged differently according to the individual differences of each of us. It is suggested to be able to detect the formaldehyde concentration in different places at the same time, multiple different colors, and the contrast color is easier to identify the formaldehyde concentration range value accurately. It's clearer than that.