Graphene oxide with covalently attached zinc monoamino-phthalocyanine coated graphite electrode as a potentiometric platform for citrate sensing in pharmaceutical preparations

• DOI: 10.1007/s10008-015-2832-9
• Publication Date: 2015-04-08T11:14:54Z
• Authors: Naglaa M. Nooredeen; M. A. Abd El-Ghaffar; W. M. Darwish; E. Elshereafy; A. A. Radwan; M. N. Abbas
• Keywords: Electrochemical gas sensor

A citrate selective coated graphite electrode (CGE) based on zinc monoamino-phthalocyanine functionalized graphene (ZnMAPc-G) has been developed and potentiometrically evaluated. The composition of the membrane prepared from ZnMAPc-G, DOS, and PVC in THF was optimized. The sensor based on ZnMAPc-G containing 5 % ZnMAPc possessed the optimum performance in glycine buffer 0.01 M of pH 3.9 with a near Nernstian slope of −57.3 ± 0.5 mV/decade, a linear range of 8 × 10−7–1 × 10−2 mol L−1 and a detection limit of 5 × 10−7 mol L−1. Different electrodes prepared using ZnMAPc as free ionophore or as composite with graphene (ZnMAPc/G) were also evaluated and compared to the electrode containing covalently attached ionophore (ZnMAPc-G). The proposed sensor possessed a long-life of about 6 months without notable drift in its slope and was utilized in the determination of the citrate concentration in some pharmaceutical formulation.