What is the correct method to measure whether formaldehyde exceeds the standard?

Everyone knows the many hazards of formaldehyde, such as causing chest tightness, dermatitis, or frequent sneezing, etc. Therefore, when moving to a new home or redecorating your home, it is best to test the formaldehyde content in the house. This is very important, but many people do not know how to detect the formaldehyde content, so the following will teach you the detection method.

First, judge by indoor smell:

Newly renovated homes and office rooms or newly purchased homes have pungent, glaring and other irritating odors, and the odors linger for a long time.

Second, judge by indoor plants:

After a new renovation, indoor plants are difficult to survive and their leaves easily turn yellow and wither; after moving into a new home, domestic cats, dogs and even tropical fish die inexplicably.

Third, judge by physical symptoms:

1. When I wake up every morning, I feel stuffy, nauseous, and even dizzy.

2. Someone in the family often catches colds and has allergies, and these problems occur in groups. Children often cough and sneeze, and their immunity is reduced.

3. Although I don’t smoke, I often feel discomfort in my throat, a foreign body sensation, and difficulty breathing.

4. Family members share a symptom, and after leaving this environment, the symptoms change and improve significantly.

Fourth, test through online self-testing instruments:

This method can only roughly detect the situation at a certain point in the room and its accuracy is not high. If the detection result after this method exceeds the standard, it is recommended that you find a professional testing agency to conduct an authoritative test in order to determine the actual situation in the room.

Fifth, conduct environmental testing through professional organizations:

Environmental testing by professional organizations is based on national indoor air quality standards. Professional indoor air quality testing equipment is used to sample indoor air, which is then sent to the laboratory for testing and analysis. The results are authoritative.

Sixth, formaldehyde detection method

The determination methods of formaldehyde include phenol reagent colorimetry, acetylacetone colorimetry, chromotropic acid colorimetry, rapid detection and other chemical methods. Instrumental methods include high performance liquid chromatography, gas chromatography and electrochemical method. The national indoor air quality standard stipulates that colorimetry, phenol reagent colorimetry and gas chromatography are standard methods for determining formaldehyde in indoor air.

1. Colorimetry

The formaldehyde in the air is absorbed by the absorption liquid, reacts with 4-amino in the alkaline solution, and is oxidized by potassium periodate to form a purple-red compound. The depth of its color is proportional to the formaldehyde content. The formaldehyde content is quantitatively determined by colorimetry.

Measurement range: If the sample volume is 20L, the measurement concentration range is 0.01-0.16mg/m3.

Detection limit: 0.13ug.

2. Formaldehyde rapid test paper

The reaction part at the front end of the test paper is yellow, and the reaction part of the test paper is darker yellow. It means that the indoor formaldehyde concentration is high; when the reaction part of the test paper is lighter yellow, it means that the indoor formaldehyde concentration is low. You should refer to the standard colorimetric card to read the approximate value to determine whether the indoor formaldehyde concentration exceeds the standard or the approximate range of the excess standard.

3. Gas phase spectrometry

Formaldehyde in the air is adsorbed on a support coated with dinitrobenzene under acidic conditions to generate stable formaldehyde hydrazone. After elution with carbon disulfide, it was separated by an OV chromatographic column and determined by a hydrogen flame ionization detector, with retention time being used for qualitative analysis and peak height for quantitative analysis.

Measuring range: If 20L is sampled at a flow rate of 0.1L/min, the measuring range is 0.02-1mg/m3.

Lower detection limit: 0.01mg/m3.

4. Formaldehyde rapid detection kit

Formaldehyde (formalin) illegally added to food can react with this reagent to produce a purple product. The depth of the purple is proportional to the residual amount of formaldehyde in the sample. Therefore, when this reagent is added to the sample solution of aquatic products or water-soaked food, if it shows an obvious purple color after the 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 into the hole of the "porous colorimetric tube". Then, use a 0.5ml pipette to absorb 0.5ml (about 10 drops) of sample exudate or immersion solution and add it to the hole. Shake to mix (preferably stir to mix). After mixing evenly, add 1 drop of test solution C about 1 minute later, observe the color change, and refer to the color card to judge the result.