This standard specifies the spectrophotometric method for determining formaldehyde concentration in air of residential areas. It is also applicable to the determination of formaldehyde concentration in air of public places.
The determination range of this standard is 0.2~3.2μg formaldehyde pollutant in 2mL of sample solution. If the sampling flow is 1L/min and sampling volume is 20L, the determination range of concentration is 0.01~0.16mg/m3.
This method will not be affected by aldehyde, propionaldehyde, n-butyraldehyde, acrolein, butenal, glyoxal, benzaldehyde, methanol, ethanol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, isobutanol, isoamylol and ethyl acetate; there is no interference from the nitrogen dioxide and sulfur dioxide coexisting in the air during the determination.
2 Principle
Formaldehyde condenses (II) with 4-amino-3-hydrazine-5-mercapto-1,2,4-triazol (I) under alkaline condition in air and is oxidized by potassium periodate and generates 6-mercapto-5-triazol [4,3-b]-S-tetrazine (III) compound (aubergine), and the color of this compound is in direct proportion to formaldehyde content. The equations are as follows:
GB/T 16129-1995 The following standards are cited：
