Modification of a pH-Titration Standardization Method for Formaldehyde

Abstract

Procedures for monitoring formaldehyde concentration in air ultimately require a standard solution with which to calibrate the response of the analytical method. Although formaldehyde solutions of nominal concentration may be prepared from a variety of sources, the solutions must be standardized. The sulfite-pW titration method was tested and found to give erratic results. This paper presents evidence to indicate that the sulfite-pHhitration procedure requires modification. This modified procedure was used to standardize solutions of free formaldehyde. One of these standardized solutions was used to calibrate the chromotropic acid colorimetric procedure for formaldehyde. The calibrated colorimetric method accurately quantitated the concentration of a solution prepared from dry sodium formaldehyde bisulfite, previously calibrated using the direct-iodinekitration method. This correlation indicates that the modified sulfite-pHhitration standardization procedure is an accurate means of standardizing formaldehyde solutions. An independent oxidatiordformate ion chromatography analysis method was devised to confirm the accuracy of the modified sulfite-pHhitration method. Gaertner, R.R.W.: Modification of a pH-Titration Standardization Method for Formaldehyde. Appl.