Fluorescence and colorimetric rapid dual-signal "on-off-on" switching detection of ascorbic acid based on TSPP/DCIP.

A fluorescence and colorimetric dual-signal sensing system for the determination of ascorbic acid (AA) in complex media was developed by using 5,10,15, 20-tetrakis(4-sulfonyl) porphyrin (TSPP) as a sensing probe and sodium 2,6-dichloroindophenol (DCIP) as a bridge. A fluorescence resonance energy transfer (FRET) effect occurred when DCIP was added to the TSPP solution, resulting in the quenching of the fluorescence signal of TSPP and a change in the color of the solution from pink to blue. The DCIP in the system reacted with AA in a redox reaction to produce colorless phenol imine, the color of the solution changed from blue to green causing an obvious colorimetric response, and the TSPP/DCIP sensing system's fluorescence signal restored owing to AA introduced. The fluorescence method for AA showed good linearity in the ranges 0.08 mM ~ 1 mM and 1 mM ~ 43.6 mM with a detection limit of 6.4 μM. And the colorimetric method for AA showed excellent linearity in the range 0.46 mM ~ 40.2 mM with a detection limit of 76.0 μM. The constructed "dual-signal" probe in the study has been successfully applied to the detection of AA in practical samples. The method proposed has great potential for practical applications and provides new ideas for the visual inspection of portable measurements.