Spectral and Electrochemical Studies of Phenazopyridine

Abstract

The spectral and voltammetric behavior of phenazopyridine (1) in aqueous buffers of varied pH is presented. Spectrophotometry, cyclic voltammetry, differential pulse polarography and coulometry were utilized to study its proton and electron transfer characteristics. Relevant thermodynamic and electrochemical data such as pKa, charge transfer co-efficient (αna), forward rate constant (k0f,h),etc., have been evaluated. An excellent electroanalytical method of assaying of 1 has been developed in differential pulse polarography at pH = 8. Molecular modeling on various acid-base conjugates of 1 and their several conformers has been carried out to arrive at the thermodynamic and conformational issues to correlate the spectral and electrochemical observations.

Fast and selective determination of phenazopyridine at a novel multi-walled carbon nanotube modified ZnCrFeO4magnetic nanoparticle paste electrode

“…Then, we have used voltammetric and electrochemical impedance spectroscopic techniques at pH 2.0 to demonstrate the electrochemical behavior of phenazopyridine on MWCNTs/ ZnCrFeO 4 /CPE. The results showed that the detection limit, linear dynamic range, and sensitivity to phenazopyridine with MWCNTs/ZnCrFeO 4 /CPE are comparable to, and even better than, those recently developed which use voltammetric methods [15][16][17][18][19][20][21] (Table 1).…”

“…Therefore, development of highly sensitive analytical methods for determination trace amount of phenazopyridine is of great signicance in clinical treatment. Several electrochemical methods have been proposed for the determination of phenazopyridine including polarography, 14 voltammetry, [15][16][17][18][19][20][21] amperometry, 22 and gravimetry. 23 Many of them are not enough sufficiently sensitive and/or are time consuming and/or used toxic materials.…”

NiFe2O4nanoparticles decorated with MWCNTs as a selective and sensitive electrochemical sensor for the determination of epinephrine using differential pulse voltammetry

“…Variation of the peak potential with pH was linear with a slope of 64 mV pH À1 and a correlation coefficient of 0.9932, which is close to that given by the Nernstian equation for equal number of electrons and protons transfer processes. 54 This behavior conrms that the numbers of electrons and protons in the oxidation reaction of epinephrine are the same 54,57,58 and are equal to two (Scheme 1).…”

Hollow fiber‐based liquid–liquid–liquid microextraction followed by flow injection analysis using column‐less HPLC for the determination of phenazopyridine in plasma and urine

“…The absorption band in the region between 350 and 450 nm is expected to be due to n →π * transition of the azopyridine moiety (Fig. 1) 32. At this wavelength, mobile phase flow rate of 1 mL/min was considered as the optimum flow rate because a peak broadening was observed at lower flow rates and no improvement in signal was seen at higher flow rates.…”