B-Cyclodextrine Modified Carbon Paste Electrode as a Selective Sensor for Determination of Piroxicam Using Flow Injection Cyclic Voltammerty

A carbon paste electrode was modified with ?-cyclodextrin to form a selective electrochemical sensor for determination of Piroxicam (PX). A novel sensitive technique which called fast Fourier transform cyclic voltammetry (FFT CV) was used for measurements of redox current of the component. To have a more defined and intense peak current for piroxicam determination, Tris-HCl buffer (pH=8.0; 0.05 mol L-1) was used as supporting electrolyte. In this aqueous media, PX has been selectively accumulated on the surface of electrode by CD as a modifier. The drug presented one irreversible oxidation peaks at about 500 mV on modified carbon paste electrode vs. Ag/AgCl which produced a higher current. This property was used for analytical purposes by developing a stripping FFTCV method to determine piroxicam. Furthermore, signal-to-noise ratio has significantly increased by application of discrete fast Fourier Transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. The effective parameters were optimized. As a result, CDL of 5.0×10-9 mol L-1 and LOQ of 8.0×10-9 mol L-1 were obtained. The electrode applied for determination of PX in urine and plasma and formulation samples. The recovery for spiked assay in urine and plasma samples was obtained 101-105% respectively and a good quantification of piroxicam was achieved in a commercial formulation. The effect of some interfering substances was investigated and electrode showed a good selectivity to piroxicam.