Catalytic Spectrophotometric Determination of Formaldehyde Based on Its Catalytic Effect on the Reaction Between Bromate and Cresyl Violet

Abstract

A new simple and rapid catalytic kinetic method for the determination of trace amount of formaldehyde is described. The method is based on the catalytic effect of formaldehyde on the oxidation of cresyl violet by bromate in the present of sulfuric acid. The reaction monitored spectrophotometrically by measuring the decrease in absorbance of the reaction mixture at 564 nm. The fixed-time method was used for the first 90 s. For initiation of the reaction, under the optimum conditions, in the concentration range of 0.02-2.00 μg mL^-1 formaldehyde can be determined with a limit of detection 0.011 μg mL^-1. The relative standard deviation of six replicate measurements is 2.5 % for 0.3 μg mL^-1 of formaldehyde. The method was used for the determination of formaldehyde in water samples with satisfactory results.