Kinetic Spectrophotometric Determination of Trace Formaldehyde in Foodstuff Based on Oxidation Discoloration of Acid Chrome Blue K with Potassium Bromate

Based on the catalytic effect of trace amount formaldehyde on oxidation of acid chrome blue K(ACBK) by potassium bromate in 0.04 mol/L sulphuric acid solution,a new kinetic spectrophotometric method for the determination of trace amount formaldehyde has been developed.The detection limit is 0.93 μg/L and the linear range of determination is 0.0-0.40 μg/mL for formaldehyde.The relative standard deviation for the determination of formaldehyde at the concentration of 5.0 μg/25 mL is calculated to be 1.9 %(n =11).The factors such as acidity,concentrations of reactants,reactive time,temperature,influence of coexisting ions on the reaction and the optimum reaction conditions of the reaction and some kinetic parameters are determined;the apparent activation energy of the reaction is 69.47 kJ/mol.The method has been applied to the determination of formaldehyde in runnet and peeled shrimp samples with the relative standard deviation of 1.1 %-2.3 % and the recovery of 98.7 %-101.4 %.