Design and fabrication of optical chemical sensor for detection of nitroaromatic explosives based on fluorescence quenching of phenol red immobilized poly(vinyl alcohol) membrane

• An optical chemical sensor was fabricated based on immobilizing phenol red into PVA.
• The chemical sensor used for the detection of nitroaromatic explosives.
• The developed method showed wide linear range 5.0×10−66 to –2.5×10−4 M for each explosive.

The present study developed a new optical chemical sensor for detection of nitroaromatic explosives in liquid phase. The method is based on the fluorescence quenching of phenol red as fluorophore in a poly(vinyl alcohol) (PVA) membrane in the presence of nitroaromatic explosives as quenchers, e.g., 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 4-nitrotoluene (4-NT), 2,4,6-trinitrobenzene (TNB), and nitrobenzene (NB). For chemical immobilization of phenol red in PVA, phenol red reacted with formaldehyde to produce hydroxymethyl groups and then attached to PVA membrane through the hydroxymethyl groups. The optical sensor showed strong quenching of nitroaromatic explosives. A Stern–Volmer graph for each explosive was constructed and showed that the range of concentration from 5.0×10−6 to 2.5×10−4 mol L−1 was linear for each explosive and sensitivity varied as TNB >TNT>2,4-DNT>NB>4-NT. The response time of the sensor was within 1 min. The proposed sensor showed good reversibility and reproducibility.

Graphical AbstractThe fluorescence excitation and emission spectra of phenol red (PR) (λex=350 nm, λem=545 nm) and PRF-PVA membrane (λex=386 nm, λem=578 nm) in methanol.Figure optionsDownload as PowerPoint slide