OPTICAL CHEMICAL SENSORS FOR PHARMACEUTICAL ANALYSIS USING 1,4-BIS(1,3-BENZOXAZOL-2-YL)BENZENE AS SENSING MATERIAL

Optical chemical sensors were prepared for the determination of ethacr ynate, berberine, picric acid and picrolonic acid in aqueous solutions based on the fluorescence quenching of 1,4-bis(1,3-benzoxazol-2-yl)be nzene (BBOB) in differently plasticized PVC membranes, The possible qu enching mechanisms are discussed in detail, The fluorescence changes o f the sensing membranes involve the formation of complexes between BBO B and the quenchers in question, The optimum pH ranges for the determi nation of ethacrynate and berberine are 4.0-10 and 8.0-11, respectivel y, whereas 1.0-2.0 and 0.90-2.3 mol l(-1) H2SO4 media are the best for picric acid and picrolonic acid, respectively, The complex compositio ns of BBOB with the four quenchers are all 1:1. The sensors respond Li nearly in the measuring ranges 8.00 x 10(-2)-1.00 x 10(-4) mol l(-1) f or ethacrynate, 6.76 x 10(-4)-1.62 x 10(-5) mol l(-1) for berberine an d picrolonic acid and 2.88 x 10(-4)-4.36 x 10(-6) mol l(-1) for picric acid. The response times to reach a stable signal were less than 30 s . In addition to the high reproducibilities, the sensors can reversibl y and selectively respond to the quenchers of interest, The proposed s ensors mere applied to the direct assay of ethacrynic acid and berberi ne hydrochloride in commercial tablets and the indirect assay of cinch onine and VB1 through quantitative precipitation with picric acid and picrolonic acid, respectively, The results were in good agreement with those obtained by pharmacopoeial and other methods.