Catalytic Kinetic Photometric Determination of Trace Amounts of Formaldehyde

In dilute H2SO4 medium,the color-fading oxidation of rhodamine B by KBrO3 was catalyzed by traces of formaldehyde.Linear relationship between the magnitude of decrease in absorbance measured at 540 nm and the concentration of HCHO was held in the range of 0.30-3.00 mg·L-1,with its detection limit of 0.15 mg·L-1.Kinetic conditions of the reaction were studied,and the proposed method was applied to the determination of trace amounts of HCHO in drinks.Recovery and precision of the method were tested,giving values of recovery and RSD′s (n=6) in the ranges of 95.5%-97.0% and 1.8%-2.0% respectively.