Study on the color-changing mechanism and law of visual formaldehyde sensing system based on hyperbranched polyamines

This study focuses on addressing the limitations associated with most chemical derivatization methods commonly used for formaldehyde detection. These methods often suffer from prolonged derivative times (≥30 min) and complex procedures, which hinder their ability to meet the requirements of real-time and accurate sensing. In this research, a novel formaldehyde indicator system based on hyperbranched polyamine molecule was developed, and its mechanism and principles of color change were investigated. The findings revealed that hyperbranched polyamine molecule effectively reacts with formaldehyde, leading to a reduction in electron cloud density in the amine group N and subsequently causing a decrease in pH value. This reaction enables the visualization of formaldehyde detection through changes in the indicator spectrum. Moreover, the spectral variation pattern exhibits a strong linear correlation with the formaldehyde concentration when the PAMAM concentration is optimized. The detection limit of this method was determined to be 1.8 ppm. Notably, the reaction between PAMAM and formaldehyde is almost instantaneous, the color change is insensitive to temperature, and the method demonstrates high selectivity. Overall, this research contributes to the advancement of real-time formaldehyde monitoring technology and provides insights for future developments in this field.