An air-driving FI device with merging zones technique for the determination of formaldehyde in beers

An air-driving flow injection device with merging zones technique is proposed for the rapid determination of formaldehyde in pale beers based on its catalytic action on the redox reaction between Victoria Blue B and potassium bromate in phosphoric acid medium. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of Victoria Blue B at the maximum absorption wavelength of 618 nm. Only 160 μL reagents and 40 μL sample solutions are needed. Formaldehyde in the range 8-700 ng mL−1 can be determined at a rate of about 50 samples h−1, the RSD for the determination of 20 ng m L−1 formaldehyde is 2.1%. Due to appropriate consideration of the beer matrix, formaldehyde in beers can be determined directly and satisfactory results were obtained.