Determination of formaldehyde in food by fading spectrophotometry with iodine- starch system

A novel method for the determination of formaldehyde by iodine-starch fading spectrophotometry has been established. The results showed that iodine and starch could form the blue complex which had maximum absorption wavelength at 580 nm,formaldehyde could be oxidized by added into iodine starch system together with sodium hydroxide,and the blue complex would reappear when the system was transformed into an acidic medium about p H4. 00 abjusted by hydrochloric acid. The absorbance of the blue complex would decrease and the reduction of absorbance( ΔA) had good linear relationship with the content of formaldehyde( ρ) from 0 to75 ng / m L. The linear regression equation was y = 0. 0063 x + 0. 0013 and the linear correlation coefficient was0. 9971. The proposed method has been applied to the determination of formaldehyde in food,and the results agreed well with those obtained by acetylacetone spectrophotometry.