scope:

Introduction

Volatile aldehydes, even at very low concentrations, can cause irritation of the human eyes and breathing passages, and also can harm plants. For some aldehydes, MAK values exist [maximum permissible workplace concentration¹⁾], which are published in the German Technical Rules for Hazardous Sub-stances (TAGS 900). For formaldehyde, an air quality guideline value [1] is specified by the WHO and the German Federal Health Office in 1977 recommended a guide value for formaldehyde concentration in indoor air [2; 3; 4]. The German Ordinance on Prohibition of Chemicals specifies, for example, a limit value for formaldehyde emissions from wood based materials.

Aldehydes can be emitted in various types of exhaust gas or are also formed in the atmosphere by photo-chemical oxidation of hydrocarbons. The aldehyde of most importance for air pollution is formaldehyde. Formaldehyde is one of the few organochemical compounds occurring as an air pollutant which can be determined at very low concentration by a specific color reaction. The occurrence of formaldehyde in indoor areas is described, inter alia, in guideline VDI 4300 Part 3.

Guideline VDI 3484 Part 1 describes photometric determination of formaldehyde by the sulfite pararosaniline method which is based on the Schiff reaction.

This Part 2 of guideline VDI 3484 also presents a wet-chemical photometric method for determining formaldehyde. In this case determination is based on the Hantz reaction, a simple method of detection for formaldehyde which has been known under the name "acetylacetone method" in the technical literature.

The standard DIN ISO 16000-3 presents a method which makes it possible to detect aliphatic and aromatic aldehydes and ketones as individual components. The substances are reacted in cartridges with 2,4-dinitrophenylhydrazine (DNPH) on a solid sorbent to give the corresponding hydrazones. After elution with acetonitrile the individual components are analyzed by high-performance liquid chromatography (HPLC).

¹⁾ MAK values arc published by the 'Senatorial commission for the examination of hazardous working materials (Senatskommission zur Prolong gesundheiLcschadlicher Arbeitsstotie)" of the (ierman Science Foundation (DEW. The list of MAK values is annually checked and enlarged.