Selective Determination of Cr(VI) by Glutaraldehyde Cross-Linked Chitosan Polymer Fluorophores

A non-conjugated polymer fluorophore (GCPF) was synthesized by crosslinking chitosan with glutaraldehyde via Schiff base reactions and systematically investigated for selective determination of Cr(VI). The results revealed that the synthesized GCPF exhibited excellent photostability and water solubility. More importantly, GCPF possessed dramatically enhanced fluorescence intensity originated from the n−π* transitions of the Schiff base sub-fluorophore groups (e.g., C=N) that can be selectively and sensitively quenched by Cr(VI) through oxidative damages to C=N group. An effective EDTA masking agent approach was employed to minimize ionic interferences. In the presence of high concentration of interference ions including Cr(III), the quenching GCPF fluorescence is capable of selectively determining Cr(VI) within a concentration range up to 50 μM and a detection limit of 0.22 μM. The analytical performance of GCPF was also confirmed by analyzing real surface water and industrial samples.