Amperometric Folic Acid Quantification Using a Supramolecular Tetraruthenated Nickel Porphyrin µ‐Peroxo‐Bridged Matrix Modified Electrode Associated to Batch Injection Analysis

Abstract

A supramolecular Nickel (II) porphyrin complex containing four pyridyl‐bis(2,2′‐bipyridyl)chloro ruthenium meso substituents was submitted to successive voltammetric cycles in high alkaline media to produce a supramolecular matrix with Nickel centers linked by µ‐peroxo bridges, producing a highly stable thin film able to act as redox mediator for electrocatalytic oxidation of folic acid. The characterization of electrode surface material was performed by Scanning Electron Microscopy and Electrochemical Impedance Spectroscopy. The modified electrode was inserted into a batch injection electrochemical cell used for the rapid and precise quantification of folic acid in pharmaceutical products. The favorable hydrodynamic conditions provided by amperometry‐BIA association allowed a very high throughput with good linear range (1 to 200 µmol L−1) and low detection limit (7.37×10−7 mol L−1). The electrochemical method was applied to the quantification of folic acid in different tablet samples. The results were comparable with values indicated by the manufacturer and those found using high HPLC according to the Brazilian Pharmacopoeia; commercial samples were submitted to a procedure in order to remove lactose of tablets, since carbohydrates act as interfering species. This procedure together with the electrochemical method showed to be simple, rapid, efficient and an appropriate alternative for quantifying this compound in real samples.

Tuning Selectivity and Sensitivity of Mixed‐polymeric Tetraruthenated Metalloporphyrins Modified Electrodes as Voltammetric Sensors of Chloramphenicol

“…The Ni‐100, Ni‐75, Ni‐50 and Ni‐25 modified glassy carbon electrodes (GCE) were prepared by electrodeposition. To prepare each modified electrode, 50 successive voltammograms were performed from 0 to 0.90 V, as previously reported , , . For the preparation of the electrode containing 25 % of Ni, it was necessary to extend the CV from 0 to 1.0 V and to 100 % of Co the potential was extend from 0.0 to 1.1 V. All cyclic voltammograms were performed using the scan rate of 0.1 V s −1 .…”

“…For preparation of the mixed electrode films, proportional aliquots of each solution were added in the electrochemical cell, according to desired electrode film, for the final volume of 500 μL, i. e. 250 μL of each solution for Ni‐50 electrode. The Ni‐25 and Co‐100 modified GC electrode were scanned respectively from 0.0 to 1.0 V and 0.0 to 1.1 V in order to get well‐defined voltammograms –,. Immediately after, the electrodes were soaked in a 0.1 M sodium hydroxide solution to remove the soluble species eventually adhered on the electrochemically deposited material.…”

“…Among many different approaches to attach metalloporphyrin on electrode surfaces, the electropolymerization of nickel tetraruthenated porphyrin films in alkaline media has demanded a particular interest due their electrochemical behaviour, very similar to a α‐Ni(OH) 2 electrode surface without exhibiting signs of conversion to β‐Ni(OH) 2 in the voltammograms. The redox activity of this material is associated to μ‐peroxo bridges (Ni−O−O−Ni) between neighboring metal centers, combined in a supramolecular polymeric matrix generated after successive voltammetric cycles during the modifications process , , . Similar films were obtained using different Ni 2+ macrocycle complexes .…”

Fast Determination of Antioxidant Capacity of Food Samples Using Continuous Amperometric Detection on Polyester Screen‐printed Graphitic Electrodes

“…The dispensing rate of 193 μL s −1 was selected for further measurements as faster injections may generate higher standard deviations (limited data points for an injection that would take less than 0.5 s if higher dispensing rates were selected). A similar trend was previously reported in BIA systems using conventional electrodes or screen‐printed electrodes .…”

Batch Injection Analysis with Amperometric Detection for DNA Biosensing Applications

“…In addition, application of new electrode materials provides improvement on sensitivity and selectivity, resulting in unique advantages for such analytical systems [6]. Glassy carbon electrodes (GCEs) [7][8][9][10][11] and boron-doped diamond electrodes (BDDEs) [12][13][14][15][16][17][18][19] were mostly used electrode materials in BIA for the determination and quantification of many compounds. Other carbon-based electrodes, such as graphite-composite electrode [20], GCE modified with multi-walled carbon nanotubes [21,22] or coated with a mercury thin film [23], as well as some metal electrodes, such as gold [24] or copper ones [25], were also successfully tested and applied.…”