Fluorescence chemical sensor for determining trace levels of nitroaromatic explosives in water based on conjugated polymer with guanidinium side groups

A novel fluorescent conjugated polymer (poly(2-amino-N-(2-((4-ethynylphenyl) ethynyl) phenyl)-5-guanidinopentanamide)-1,4-phenylethynylene-1,4-phenyleneethynylene, PPE-Arg) was synthesized in this paper. We found that PPE-Arg could be quenched by picric acid (PA). Photoinduced electron transfer (PET) mechanism can be used to describe the fluorescence quenching of PPE-Arg. It could be speculated that the photo-induced electrons may be transferred from PPE-Arg to nitroaromatic explosives. In this paper, the experiment conditions and detection performance of PPE-Arg were systematically studied. The experiment results demonstrate PPE-Arg as a sensor for PA has a good linear range from 5 × 10⁻⁷ to 6 × 10⁻⁵ mol L⁻¹ with the calculated limit of detection (LOD) to be 1.0 × 10⁻⁷ mol L⁻¹. Meanwhile, reaction time between PPE-Arg and PA is less than 1 min. This proposed sensor was applied to rapidly detect nitroaromatic explosives in environmental water samples and satisfactory results were obtained.