A fluorescent dosimeter for formaldehyde determination using the Nash reagent in silica gel beads

Based on the Nash reagent embedded in silica gel beads as a recognition element, a fluorescent dosimeter for formaldehyde determination is established. The system can act as a fluorescent off–on switch for the qualitative detection of formaldehyde. The fluorescence emission of the Nash reagent-loaded silica gel beads is “switches off” (or very low) before exposure to formaldehyde, while fluorescence can be switched on when the beads are contacted with formaldehyde. The slope of fluorescence time scan spectra changes with formaldehyde concentration, which constitutes the basis of quantitative determination of formaldehyde concentration. The formaldehyde can also be semi-quantitatively measured in a naked-eye-detectable fashion. No response of this dosimeter to primary alcohols, ketones and other common substances was observed. The dosimeter is sensitive, inexpensive, a disposable, and simple in operation.