Determination of Diclofenac on a Dysprosium Nanowire- Modified Carbon Paste Electrode Accomplished in a Flow Injection System by Advanced Filtering

Abstract

A new detection technique called Fast Fourier Transform Square-Wave Voltammetry (FFT SWV) is based on measurements of electrode admittance as a function of potential. The response of the detector (microelectrode), which is generated by a redox processes, is fast, which makes the method suitable for most applications involving flowing electrolytes. The carbon paste electrode was modified by nanostructures to improve sensitivity. Synthesized dysprosium nanowires provide a more effective nanotube-like surface [1-4] so they are good candidates for use as a modifier for electrochemical reactions. The redox properties of diclofenac were used for its determination in human serum and urine samples. The support electrolyte that provided a more defined and intense peak current for diclofenac determination was a 0.05 mol L−1 acetate buffer pH = 4.0. The drug presented an irreversible oxidation peak at 850 mV vs. Ag/AgCl on a modified nanowire carbon paste electrode which produced high current and reduced the oxidation potential by about 100 mV. Furthermore, the signal-to-noise ratio was significantly increased by application of a discrete Fast Fourier Transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. To obtain the much sensivity the effective parameters such as frequency, amplitude and pH was optimized. As a result, CDL of 2.0 × 10−9 M and an LOQ of 5.0 × 10−9 M were found for the determination for diclofenac. A good recovery was obtained for assay spiked urine samples and a good quantification of diclofenac was achieved in a commercial formulation.

Flow‐Injection Amperometric Method for Determination of Diclofenac in Pharmaceutical Formulations Using a Boron‐Doped Diamond Electrode

“…In the recommended daily dosage (50 to 150 mg), DCF is well tolerated and due to this, it is a nonsteroidal anti-inflammatory drug of first choice used in the treatment of chronic and inflammatory conditions [3]. However, in an overdose dosage, several unwanted side effects can occur during treatment such as gastropathy, nonsteroidal drug colitis, degenerative and inflammatory liver alterations, and both morphological and functional renal changes [4].…”

“…Several methods for the determination of DCF have been reported in the literature, such as high performance liquid chromatography (HPLC) with electrochemical or UV detection [5][6][7], spectrophotometry [8,9], spectrofluorometry [10,11], gas chromatography [12], capillary zone electrophoresis [13,14], and electrochemistry [15,3,[16][17][18][19][20][21]. In all electrochemical methods, modified electrodes were used due to the gradual passivation or contamination of unmodified solid working electrodes occurred during the DCF oxidation (adsorption of the electrochemically generated product).…”

Electrochemical Determination of Diclofenac Sodium in Aqueous Solution on Cu‐Doped Zeolite‐Expanded Graphite‐Epoxy Electrode

“…This test was run in 0.1 M NaOH as supporting electrolyte and a recovery of 97.8% with a RSD of 2.5% was found. Comparing the lowest limit of detection obtained with this type of electrode and proposed preconcentration-voltammetric scheme with other reported methods [2,20,21], the results are superior to the previous reported methods, except the work that reported the limit of detection of 2 10 À9 M using Fast Fourier Transform Square-Wave Voltammetry on a dysprosium nanowire-carbon paste electrode accomplished in a flow injection system by advanced filtering [19]. …”

“…However, most of these techniques are time-consuming, laborious to perform or require chemical reagents, thus electrochemical methods have attracted interest, because of the fast response, large sensitivities, simple operation, and the possibilities of miniaturization [12][13][14][15][16][17][18][19][20][21][22][23][24]. Among the electrochemical methods, various voltammetric/amperometric [14][15][16][17][18][19] and potentiometric techniques [20][21][22][23][24] have been reported for the determination of diclofenac.…”

Simultaneous Determination of Amoxicillin and Diclofenac in Pharmaceutical Formulations Using UV Spectral Data and the PLS Chemometric Method

“…4 Its mechanism of action is associated principally with the inhibition of prostaglandin synthesis (specifically, inhibition of cyclooxygenase). 5,6 Different methods for the quantitative determination of these drugs in pharmaceutical preparations and biological fluids have been reported, including UV-vis spectroscopy, [7][8][9][10][11][12][13][14][15][16][17] UV spectroscopy with chemometric analysis, [18][19][20] spectrofluorometry, [21][22][23][24] potentiometry, [25][26][27][28][29] chromatography, 30-37 electrophoresis capillary, [38][39][40][41][42] Fourier transform spectroscopy, 43 FT-Raman spectroscopy, 44 FT-Raman spectroscopy with chemometric analysis, 45 and sequential flow injection; 46,47 however, none of the above procedures is suitable for the simultaneous determination of amoxicillin trihydrate (AMT) and DIC in commercial tablet pharmaceutical preparations. The instrumental methods above mentioned are important referential methods, but are based on expensive analytical instruments, which are not available for laboratories that carry out routine quality controls and have low economic resources.…”