The content of free formaldehyde* and the total formaldehyde content* in an interior paint can be determined according to VDL Guideline 03. The concentration of formaldehyde is determined via the colour strength with a photometer. With this method, the free formaldehyde content can be determined down to the trace range of 0.1 ppm. When determining the amount of total formaldehyde, formaldehyde is first separated by steam distillation. Then a colour complex with formaldehyde is formed, which is measured photometrically. RMI analytics uses this method, for example, to check that allergy paints are formaldehyde-free.
Photometry can also be used to determine the chromate content in cementitious systems such as tile adhesives or plasters. These building materials must be chromate-free, as chromium(VI) compounds can cause skin diseases.
* Accredited test