Rapid, wide-range and low-cost determination of formaldehyde based on porous silica gel plate by digital image colorimetry

A porous silica gel plate impregnated with a colorimetric reagent, 4-amino-3-penten-2-one (Fluoral-P), has been fabricated for the first time to determinate formaldehyde. The reaction of formaldehyde and Fluoral-P produced a yellow product 3,5-diacetyl-1,4-dihydrolutidine (DDL) which was further photographed by a digital camera. A good linear relationship has been found between the intensity of blue component from the digital image and formaldehyde concentration in the range of 0-50 mg L^-1 with low detection limit of 2.2 0.1 mg L^-1. A good precision in the range of 0.59-7.75%RSD and an accuracy with the relative error of +3.7% from control samples are also obtained. These results demonstrate that our developed low cost sensor together with digital image colorimetry is potential in sensitively and quickly measuring formaldehyde.