A highly sensitive and selective detection of p-phenylenediamine (PPD) is achieved by a fluorescence sensor, which is constructed by encapsulating the hydrophobic fluorescent 1-pyrenecarboxaldehyde (Py-CHO) into a polymeric ionic liquid (PIL)-based amphiphilic block copolymer (BCP) micelle. The amine-aldehyde condensation reaction between PPD and Py-CHO leads to the fluorescence quenching of Py-CHO, giving rise to the basis for the quantitative detection of PPD. The core cavity of the micelle formed by the self-assembly of PIL provides an excellent hydrophobic environment for the accommodation of fluorescent Py-CHO, offering significant improved sensitivity and selectivity for PPD detection. The amount of PIL in fabricating the amphiphilic BCP micelle, the BCP-Py-CHO micelle concentration, and the detection pH condition are investigated to obtain the best performance of this sensor. The accurate detection of PPD is achieved in the range of 0.02-10 μmol L-1 under optimal conditions, and the detection limit is 0.007 μmol L-1 (3σ/ s). The developed sensor is successfully applied to the determination of PPD contents in hair dyes, spiked water, and urine samples.
Keywords: 1-pyrenecarboxaldehydes; amphiphilic block copolymer micelle; fluorescence sensor; p-phenylenediamine; polymeric ionic liquid.