AN OPTICAL-FIBER SENSOR FOR BERBERINE BASED ON IMMOBILIZED 1,4-BIS(NAPHTH[2,1-D]OXAZOLE-2-YL)BENZENE IN A NEW COPOLYMER

A new copolymer made of 8-quinolyl methacrylate, methyl methacrylate a nd n-butyl acrylate(PQMB) has been used as a solid substrate for the p reparation of an optical fiber berberine sensor. The sensing is based on the fluorescence of 1,4-bis(naphth[2,1-d]oxazole-2-yl)benzene(BNOB) immobilized in the copolymer quenched by berberine with the formation of 1:1 complex between them. The membrane composition was optimized u sing the orthogonal experimental design. Using the sensor described ab ove, berberine in a sample solution from 4.02 x 10(-7) mol l(-1) to 2. 82 x 10(-4) mol l(-1) can be detected. The sensor has satisfactory rev ersibility and a short response time of less than 30 s. The relative s tandard deviations for repeated measurements (n = 15) of 8.05 x 10(-6) mol l(-1) and 4.02 x 10(-5) mol l(-1) beberine are 0.43% and 0.33%, r espectively. The sensor shows good selectivity over alkali and alkali- earth metal sails and some common pharmaceutical species and can be us ed for the determination of berberine in pharmaceutical preparations. (C) 1998 Elsevier Science B.V. All rights reserved.