In this Thesis, a kinetic spectrophotometric method was developed for the determination of formaldehyde based on the catalytic effect of formaldehyde on the oxidation of pyrogallol red by bromate in acidic media. In part one the reaction was monitored spectrophotometrically by measuring the decreasing in absorbance of pyrogallol red at 470 nm by a fixed time method. Under the optimum conditions, a detection limit of 0.16 mg.mL -1 and the linear calibration curve was achieved for formaldehyde concentration range of 0.20-15.0 mg.mL -1 . The relative standard deviations for ten replicate measurements of 2.0 and 8.0 mg.mL -1 formaldehyde were 2.6% and 1.1%, respectively. The influence of several organic and inorganic compounds on selectivity was studied. Formaldehyde was determined in real samples such as melamine-formaldehyde resin, shampoo and water by this method with satisfactory results. In part two, a simple and sensitive flow injection method with spectrophotometric detection was proposed for determination of formaldehyde based on the catalytic effect of formaldehyde on the oxidation of pyrogallol red with bromate in acidic media. The decrease in absorbance of the reaction mixture was measured at 470 nm. The calibration graph was linear in the range of 0.47 to 40.0 ?g/mL formaldehyde with a sample rate of 30 ± 5 samples h -1 and with limit of detection of 0.36 ?g/mL. The relative standard deviations for ten replicate measurements of 2.5, 5.0 and 20.0 ?g/mL formaldehyde were 4.0, 2.1 and 0.7%, respectively. The method was applied to the determination of formaldehyde in river water, shampoo and melamine-formaldehyde resin.
