A new spectrophotometric method for determination of formaldehyde in aqueous medium

A spectrophotometric method based on the use of sodium salt of 8-amino-1-naphthol-3,6-disulfonic acid (H-acidNa) was developed for the determination of formaldehyde in aqueous solutions. Both wavelengths of 419 nm and 465 nm were applicable for analysis with appreciable molar absorptivities. The proposed method has shown several advantages such as safe analysis in diluted acidic medium, unnecessity for additional oxidants, to work at temperatures lower than the boiling temperature of water, well reproducibilities and selectivity for acetaldehyde, achieving Limit of Detection (LOD) and Limit of Quantification (LOQ) values of 0.062 mg/L (ppm) and 0.207 mg/L (ppm) at 419 nm, respectively. Although the reagent has potential to react with acetaldehyde, in the working range of 0.0-2.0 mg/L (ppm), the concentrations of acetaldehyde up to 35 times of formaldehyde's showed tolerable interference (<2.6%). The method demonstrated high sensitivity, operational simplicity, and suitability for routine analysis of formaldehyde in aqueous samples in the presence of acetaldehyde, butyraldehyde, benzaldehyde, acetone and ethyl methyl ketone.