Miniaturized potentiometric sensors based on β-cyclodextrins (β-CDs) are described for determination of metformin (Mf) in pharmaceutical preparations and biological fluids. Electrode matrix compositions are optimized on the basis of the nature and content of sensing ionophore, ionic sites and plasticizers. Coated wire electrodes (CWEs) modified with heptakis(2,3,6-tri-O-methyl)-β-CD, sodium tetrakis(4-fluorophenyl)borate (NaTFPB) and 2-fluorophenyl 2-nitrophenyl ether (f-NPE), work satisfactorily in the concentration range from 10(-6) to 10(-1) mol L(-1) with Nernstian compliance (55.7 ± 0.4 mV per decade activity) and a detection limit of 8 × 10(-7) mol L(-1). Incorporation of β-CD as a molecular recognition element improved the electrode sensitivity and selectivity due to encapsulation of Mf into the β-CD cavity (host-guest interaction). The developed electrodes have been successfully applied for the potentiometric determination of Mf under batch and flow injection analysis (FIA). FIA allows analysis of 90 samples per h offering the advantages of simplicity, accuracy and automation feasibility. The dissolution profile for metformin pharmaceutical samples (Cidophage®) was monitored using the proposed electrode in comparison with the official spectrophotometric methods. Characterization of the formed Mf-β-CD inclusion complexes is discussed in detail.

The construction and performance characteristics of new sensitive and selective sensors based on functionalized multi-walled carbon nanotubes/b-cyclodextrin nanocomposite (FMWCNTs/b-CD) was demonstrated for potentiometric determination of different anti-inflammatory agents including lornoxicam, meloxicam, piroxicam and tenoxicam. Screen printed sensors (SPEs) modified with FMWCNTs/b-CD composite, hyamine (Hy) and 2-fluorophenyl 2-nitrophenyl ether (f-PNPE) showed proper electroanalytical performances with a Nernstian compliance range between 61.2 and 52.6 mV decade À1 activity and a detection limit of 6.0 Â 10 À7 mol L À1 for different oxicam derivatives. Modification with carbon nanotube composite as sensing material remarkably improved the potential stability and lifetime of the fabricated sensors. The proposed sensors offer a simple analytical tool for determination of different oxicam derivatives in their pharmaceutical formulations under batch and flow injection analysis (FIA) conditions.