An indirect determination of formaldehyde in air samples is described. The method is based on colour reaction of formaldehyde, p-amino benzene sulphonic acid and sulphur dioxide in hydrochloric acid medium. The absorbance of pinkish-red coloured dye formed is measured at 510 nm. The colour system obeys Beer's law in the range of 1.8 to 9.6 μg of formaldehyde per 25 ml (0.072 – 0.38 ppm). Optimum conditions for colored development, and possible interferences, have been studied. The method is simple, sensitive and cost effective and have been used for the determination of formaldehyde in varies environmental samples.
Absorbance, Formaldehyde, p-Amino benzene sulphonic acid, Environmental samples, Interference
