Determination of Formaldehyde Based on the Fading Reaction of Bordeaux R by Flow Injection Spectrophotometry

A method for determination of formaldehyde by flow injection spectrophotometry based on the catalytic effects of formaldehyde on the oxidation reaction of Bordeaux R by potassium chlorate in sulfuric acid medium was established. The relationship of the reduced absorbency to the concentration of formaldehyde was good linearity and the maximum absorption peak located at 520nm. The affecting factors on the strength of absorption including acidity, dosage, temperature, coexisting ions and so on, and the optimal conditions of the reaction in the system were investigated. Calibration graphs were linear for ranges of 0 to 3.0 mg l−1 and a detection limit of 2×10-8 g ml−1 formaldehyde was achieved. The proposed method was successfully applied to the analyses of environmental samples, with relative standard deviation of less than 1.6% and the recoveries are 93.6 % to 94.5% for the determination of formaldehyde.