The chemistry of the chromotropic acid method for the analysis of formaldehyde

Formaldehyde is present in the indoor air of many industrial and non-industrial environments. The procedure for its analysis which is commonly employed in North America is a NIOSH recommended one that uses chromotropic acid and concentrated sulphuric acid. The nature of the purple chromogen that is...

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Bibliographic Details
Published in:Canadian journal of chemistry 1989-05, Vol.67 (5), p.871-876
Main Authors: Georghiou, Paris E, Ho, Chi Keung (Jimmy)
Format: Article
Language:English
Subjects:
Analysis methods
Applied sciences
Atmospheric pollution
Exact sciences and technology
Pollution
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Summary:Formaldehyde is present in the indoor air of many industrial and non-industrial environments. The procedure for its analysis which is commonly employed in North America is a NIOSH recommended one that uses chromotropic acid and concentrated sulphuric acid. The nature of the purple chromogen that is produced in the analytical procedure has not been fully understood until now. Using 1 H and 13 C nuclear magnetic resonance spectroscopic techniques and calibration line studies, evidence has been obtained to support the hypothesis that the chromogen has a mono-cationic dibenzoxanthylium structure and not a para,para-quinoidal one that is commonly cited. Keywords: Formaldehyde, formaldehyde analysis, chromotropic acid, chromogen, dibenzoxanthylium cation.
ISSN:0008-4042
1480-3291
DOI:10.1139/v89-135