Development and application of graphite-SiO2/Al2O3/Nb2O5-methylene blue (GRP-SiAlNb-MB) composite for electrochemical determination of dopamine.

In the present paper an amperometric sensor based on graphite-SiO₂/Al₂O₃/Nb₂O₅- methylene blue (GRP-SiAlNb-MB) composite has been successfully prepared for dopamine (DA) determination in real samples. The electrochemical behavior of DA at the GRP-SiAlNb-MB has been evaluated by employing cyclic voltammetry. The best ratio (m/m) of GRP-SiAlNb-MB composite was found to be 1:0.54. Under optimized conditions (pH 7.5 in 0.15 mol L_-1 phosphate buffer) the amperometry method responds linearly to DA from 5.0 up to 500.0 lmol L_-1 (r= 0.995) with limits of detection and quantification of 1.49 and 4.97 lmol L_-1, respectively. The developed method was successfully applied for DA determination in real samples of pharmaceutical formulations and can be used for routine quality control analysis of pharmaceutical formulations containing DA. The use of inorganic matrix SiAlNb was found to be very useful to adsorb MB in the composite material with further improvement of the anodic peak current of DA. [ABSTRACT FROM AUTHOR]