Determination of Vaporized Nitroaromatics in Soil by a Self-Assembled Monolayer Film

ABSTRACT

A novel self-assembled monolayer fluorescent film sensor for the determination of vaporized nitroaromatics was prepared using poly(9,9-didecyl-2,7-diethynyl-9H-fluorene-co-alt-dihexadecyloxyphenylene) on a silicon wafer. Poly(9,9-didecyl-2,7-diethynyl-9H-fluorene-co-alt-dihexadecyl-oxyphenylene) was synthesized using Sonogashira coupling between 2,7-bis(ethynyl)-9,9-didecylfluorene, and 1,4-dihexadecyloxy-2,5-diiodobenzene. The polymer was chemically attached to the film on the surface of an azide-functionalized silicon wafer. The emission spectra of the film were stable in the presence of analyte vapor over a range of temperature, allowing practical analysis. The self-assembled monolayer film was sensitive to 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, and picric acid. The self-assembled monolayer film produced 78% and 76% quenching within 30 s in the presence of 2,4-dinitrotoluene and 2,4,6-trinitrotoluene vapor. The quenching efficiency was up to 79% within 120 s for picric acid vapor. The application of the film for the determination of nitroaromatic explosives in soil was evaluated. The limits of detection were 6.9, 9.1, and 20.6 ng g⁻¹ for 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, and picric acid. These results demonstrate novel fluorescence sensing for the determination of vaporized nitroaromatics.

KEYWORDS:

• Fluorescence
• nitroaromatic explosives
• quenching
• self-assembled monolayer film