PH-sensitive fluorescent organic nanoparticles: Off-on fluorescent detection of furfural in transformer oil

Abstract

Furfural content is considered as index to estimate transformer remnant life. Therefore, low cost, highly sensitive methods for determination of furfural are highly desirable. In the present work, we describe a new strategy for furfural detection by tracing the “off-on” fluorescence signals of fluorescent organic nanoparticles (FONPs). Significant H+-dependent emission characteristics in aprotic organic solvent was found for our synthesized poly(DOPA)-FONPs. The fluorescence of poly(DOPA)-FONPs can be quickly quenched by hydroxylamine hydrochloride. Furfural can react with hydroxylamine hydrochloride to produce furan-2-carbaldehyde oxime and release proton in a 1:1 proportion. Then H+ produced by the reaction caused the fluorescence intensity at 520 nm to increase as a linear function of furfural concentrations. Under the optimum conditions, the linear working concentration range was found to be 0.01–30 mg L-1 and the LOD for the determination of furfural was 0.0015 mg L-1. The proposed method was used to determine furfural in transformer oil samples satisfactorily, providing a convenient alternative to conventional techniques.