Improved Chromotropic Acid Determination of Formaldehyde Evolution from Wood Composites

A simple, rapid and precise method of determining formaldehyde evolved from ground, air-dried samples of urea- or phenolformaldehyde-bonded particleboards or plywood is described. The determination may be carried out at room temperature on one-gram samples using readily available equipment. Nitrogen gas is passed through the apparatus and the formaldehyde is absorbed in a solution of chromotropic acid. The absorbance is measured at a wavelength of 570 nm. Using one-gram samples with moisture contents of 8 percent or less, the determination is complete in 3 to 4 hours. The method is sensitive, being capable of detecting 1 ug of formaldehyde. The precision at the specified sample moisture content is of the order of 5 percent at the 30 ug formaldehyde level.

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