Catalytic Method for Polarographic Determination of Trace Amount of Formaldehyde

In a dil.H2SO4 medium,the redox reaction between KBrO3 and methyl red was strongly catalyzed by trace amounts of formaldehyde,and at the same time,sensitive polarographic adsorption waves were produced at the dropping mercury electrode by either methyl red or its oxidation product at peak potentials of -0.57 V and -0.49 V (vs.SCE) respectively.The 2nd derivative of peak current (I″p) of methyl red measured at -0.57 V kept a linear relationship with the concentration of formaldehyde present in the reaction system in the range of 0.2-6.5 mg·L-1.Based on these facts,a catalytic polarographic method for determination of trace amounts of formaldehyde was proposed.Detection limit of the method was found to be 0.041 mg·L-1.Value of RSD (n=8) of 1.8% was obtained at the concentration level of 2.5 mg·L-1 of for maldehyde.Recovery found by standard addition method were in the range of 97.0% to 104.0%.