Simple and Sensitive Kinetic Spectrometric Methods for Determination of Formaldehyde in Rainwater Samples

Background: In the present work, two spectrometric methods for determination of formaldehyde were studied and compared. Methods and Results: Both methods are based on the catalytic effect of formaldehyde on the oxidation of Fluorescein natrium by sodium bromate in acid media. In the first method, the decrease in fluorescence intensity of Fluorescein natrium, measured at the emission wavelength of 510 nm (excitation wavelength, 438 nm), was proportional to formaldehyde in the concentration range 0.05-1.2 μg mL-1 and the detection limit was found to be 0.02 μg mL-1. In the second method, the decrease in absorbance of Fluorescein natrium measured at the wavelength of 438 nm was proportional to formaldehyde concentration in the range 0.5-7 μg mL-1 and the detection limit was found to be 0.16 μg mL-1. As preliminary steps, the working parameters (acidity, concentration of reagents, reaction time) were established. Influence of interfering species was also investigated. Conclusion: The proposed methods were applied for the determination of formaldehyde in rainwater samples.