Sensitive and visual detection of p-phenylenediamine by using dialdehyde cellulose membrane as a solid matrix.

A novel method was developed for the sensitive and visual detection of p-phenylenediamine (PPD) via immobilizing the target specie PPD on dialdehyde cellulose membrane (DCM) followed by the reaction with salicylaldehyde. The obtained solid fluorescent membrane (S-PPD-DCM) emitted yellow fluorescence under 365 nm UV light. DCM was not only used as a solid matrix but also played a vital role in the enrichment of PPD. Experimental variables influencing the fluorescence signal were investigated and optimized. Under the optimum conditions, a detection limit of 5.35 μg L-1 was obtained and two linear ranges were observed at 10-100 and 100-1000 μg L-1, respectively. Moreover, the fluorescence of the resultant membrane can still be visualized by naked eye when PPD concentration was 50 μg L-1. The detection of PPD was hardly affected by the coexistence of 1 mg L-1 of o-phenylenediamine, m-phenylenediamine or phenylamine, exhibiting good selectivity. The developed method involved in a two-step Schiff base reaction and enhanced the fluorescence emission via blocking nonradiative intramolecular rotation decay of the excited molecules. It was applied to determine the PPD in spiked hair dye with satisfactory results.