Determination of formaldehyde vapour in the atmospheres of clinical laboratories using chromotropic acid

Abstract

Ethanol and xylene vapours were found to interfere with the determination of formaldehyde vapour by the chromotropic acid method, whether water or a mixture of chromotropic and sulphuric acids were used as the scrubbing solution. The interference can be removed by a porous polymer sorbent, Tenax GC. Thus, with a Tenax GC pre-trap, the chromotropic acid method can be applied to the determination of formaldehyde vapour in clinical laboratories where alcohol and xylene vapours are often encountered. The advantages of selecting chromotropic-sulphuric acid instead of water as the scrubbing solution are discussed.