Porphyrin–metalloporphyrin composite based optical fiber sensor for the determination of berberine Original Research Article

A berberine (BE)-sensitive optical fiber sensor has been prepared using a composite active material consisting of tetraphenylporphine (TPPH2) and chloro(tetraphenyl-porphinato)manganese (TPPMnCl) in a PVC matrix. The response of the sensor is based on the fluorescence quenching of TPPH2–TPPMnCl by BE. The proposed sensor shows response to BE in the concentration range 7.5×10−7 to 5.6×10−4 mol l−1, with a wide working pH range from 5.4 to 12.7, and a fast response time of less than 20 s. The sensor shows fair selectivity towards BE with respect to common co-existing species. The sensor based on TPPH2–TPPMnCl composite shows better response characteristics comparing to that of the single TPPH2. The effect of the composition of the sensor membrane has been studied and the experimental conditions optimized. The contents of BE in pharmaceutical tablets were determined by the proposed sensor and the results agreed with values obtained by the pharmacopoeia method.