Development and validation of a novel fluorescence method via sequential injection analysis to determine formaldehyde in drinking water

Abstract

Herein, a new method for the determination of formaldehyde in drinking water was proposed by sequential injection analysis using a fluorescent filter detector. The method allowed the determination of formaldehyde at 0.05 mg L⁻¹, which is below the permissible limit of formaldehyde in drinking water (0.9 mg L⁻¹), without a preconcentration step. The method was optimized using factorial designs evaluating the principal factors: 2,4-pentanedione concentration, volume of the reagent and buffer, reaction pH, temperature and aspiration sequence. A twice injection of the sample at the beginning and end of the sequence allowed the quantification of formaldehyde at 0.05 mg L⁻¹. Once the method was optimized, it was validated using the principal parameters such as linear range (from 0.05 mg L⁻¹ to 1.0 mg L⁻¹); detection limit (0.01 mg L⁻¹); intra-laboratory reproducibility of 6.73% and recoveries between 86% and 124% for different samples of drinking water. The method is simple and it can be easily implemented in routine laboratories, and it could be easily automated.