Determination of Folic Acid by Adsorptive Stripping Voltammetry at a Lead Film Electrode

Advances in Folic Acid Biosensors and Their Significance in Maternal, Perinatal, and Paediatric Preventive Medicine

Auxotrophic primates like human beings rely on exogenous dietary vitamin B9 supplementation to meet their metabolic demands. Folates play a crucial role in nucleotide synthesis and DNA methylation. Maternal folate deficiency causes several pregnancy-related complications, perinatal defects, and early childhood cognitive impairments. New evidence suggests excess FA is a potential risk factor resulting in unfavourable genomic and epigenomic alterations. Thus, it is essential to revisit the need to consistently monitor maternal folate levels during pregnancy. Yet, to date, no point-of-care folate-monitoring biosensor is commercially available. Here, we critically appraise the advances in folate biosensors to understand the translational gaps in biosensor design. Further, our review sheds light on the potential role of folate biosensors in strengthening maternal, perinatal, and child healthcare.

Different Aspects of the Voltammetric Detection of Vitamins: A Review

Vitamins comprise a group of organic chemical compounds that contribute significantly to the normal functioning of living organisms. Although they are biosynthesized in living organisms, some are also obtained from the diet to meet the needs of organisms, which is why they are characterized as essential chemical compounds. The lack, or low concentrations, of vitamins in the human body causes the development of metabolic dysfunctions, and for this reason their daily intake with food or as supplements, as well as the control of their levels, are necessary. The determination of vitamins is mainly accomplished by using analytical methods, such as chromatographic, spectroscopic, and spectrometric methods, while studies are carried out to develop new and faster methodologies and techniques for their analysis such as electroanalytical methods, the most common of which are voltammetry methods. In this work, a study is reported that was carried out on the determination of vitamins using both electroanalytical techniques, the common significant of which is the voltammetry technique that has been developed in recent years. Specifically, the present review presents a detailed bibliographic survey including, but not limited to, both electrode surfaces that have been modified with nanomaterials and serve as (bio)sensors as well as electrochemical detectors applied in the determination of vitamins.

Electroanalysis of isoniazid and rifampicin: Role of nanomaterial electrode modifiers

Thanks to operational simplicity, speediness, possibility of miniaturization and real-time nature, electrochemical sensing is a supreme alternative for non-electrochemical methodologies in drug quantification. This review, highlights different nanotech-based sensory designs for electroanalysis of isoniazid and rifampicin, the most important medicines for patients with tuberculosis. We first, concisely mention analyses with bare electrodes, associated impediments and inspected possible strategies and then critically review the last two decades works with focus on different nano-scaled electrode modifiers. We organized and described the materials engaged in several categories: Surfactants modifiers, polymeric modifiers, metallic nanomaterials, carbon based nano-modifiers (reduced graphene oxide, multi-walled carbon nanotubes, ordered mesoporous carbon) and a large class of multifarious nano composites-based sensors and biosensors. The main drawbacks and superiorities associated with each array as well as the current trend in the areas is attempted to discuss. Summary of 79 employed electrochemical approaches for analysis of isoniazid and rifampicin has also been presented.

Evaluation of amperometric dot microsensors for the analysis of folic acid in pharmaceutical tablets and urine samples

Nineteen amperometric dot microsensors based on graphite and graphene modified with a selection of porphyrins and phthalocyanines were evaluated and tested for their ability of the analysis of folic acid in pharmaceutical tablets (e.g. Acifol) and biological samples (e.g. urine), using differential pulse voltammetry. Cyclic voltammetry was used to optimize the working conditions, e.g. pH and electrolyte for the proposed amperometric dot microsensors. The optimum working pH was 7.0 (phosphate buffer), with a 0.1 M potassium chloride supporting electrolyte. The linear concentration ranges for folic acid were between 10-6 and 10-3) M for all dot microsensors except dot microsensors based on graphite modified with tetraamino cobalt(II) phthalocyanine and tetranitro manganese(II) phthalocyanine which had linear concentration ranges between 10-6 and 10-4 M . The highest sensitivity (0.770 nA. mmolL-1) was recorded for the graphite modified with tetraamino cobalt(II) phthalocyanine based dot sensor and the lowest limit of detection (1.14 10-7 M ) for the graphite modified with tetranitro zinc(II) phthalocyanine based dot sensor. The dot sensors were used for the reliable analysis of folic acid in Acifol tablets and urine samples, with recoveries higher than 94.00% and 99.00%, respectively.

Ion-transfer voltammetric determination of folic acid at meso-liquid–liquid interface arrays

Voltammetric studies on the simple ion transfer (IT) behaviors of an important water-soluble B-vitamin, folic acid (FA), at the liquid–liquid (L–L) interface were firstly performed and applied as a novel detection method for FA under physiological conditions. This work provides a new and attractive strategy for the detection of FA⁻ and other biological anions.

New voltammetric strategy for simultaneous determination of N-acetylcysteine and folic acid using a carbon nanotube modified glassy carbon electrode

A novel 1-benzyl-4-ferrocenyl-1H-[1,2,3]-triazole (BFT)/carbon nanotube modified glassy carbon electrode (BFT-CNT-GCE) was prepared for the simultaneous determination of N-acetylcysteine (NAC) and folic acid (FA). Cyclic voltammetry (CV), chronoamperometry (CHA), and square wave voltammetry (SWV) methods were used to investigate the modified electrode for the electrocatalytic oxidation of NAC and FA in aqueous solutions. The separation of the oxidation peak potentials for NAC-FA was about 280 mV. The calibration curve obtained for NAC was in the range of 0.1-600.0 μM. The detection limit (S/N=3) was 62.0±2.0 nM for NAC. The diffusion coefficient and the catalytic rate constant for the oxidation of NAC at the modified electrode were calculated as (3.5±0.2)×10(-5) cm(2) s(-1) and (9.85±0.4)×10(-4) M(-1) s(-1), respectively. The method was employed for the determination of NAC and FA in some real samples.

Influence of Pb(II) concentration and pH of acetate buffer on the potential window of a lead film electrode: an Atomic Force Microscopy Study

Atomic force microscopy (AFM) studies on observations of lead films deposited from the solutions containing an acetate buffer and different concentration of Pb(II) are presented. AFM images show considerable variability in morphology of the deposited lead layer depending on experimental conditions. To investigate effects of the Pb(II) concentration and pH of the supporting electrolyte on the accessible potential window of the lead film electrode (PbFE), voltammetric techniques were used. It was found that the useful potential window of PbFE is affected by the pH and Pb(II) concentration. Additionally, it was found that the distribution and large size of Pb particles on the electrode surface shown by AFM corresponded well to the mass of Pb expected on the glassy carbon support with respect to the voltammetric data. Results reveal that PbFE is an attractive nonmercury metallic electrode suitable for electrochemical detection of metal ions and a lot of organic compounds in a wide potential window. The accessible potential window of the PbFE in an acetate buffer (pH = 5.0) was compared to those obtained at the bismuth film electrode and antimony film electrode.

Simultaneous and selective voltammetric determination of , and at a nanoparticles modified paste electrode

A new carbon paste electrode modified with ZrO2 nanoparticles (ZONMCPE) was prepared, and used to study the electrooxidation of epinephrine (EP), acetaminophen (AC), folic acid (FA) and their mixtures by electrochemical methods. The modified electrode displayed strong resolving function for the overlapping voltammetric responses of EP, AC and FA into three well-defined peaks. The potential differences between EP - AC, AC - FA and EP - FA were 210, 290 and 500 mV respectively. Differential pulse voltammetry (DPV) peak currents of EP, AC and FA increased linearly with their concentration at the ranges of 2.0 × 10-7-2.2 × 10-3 M, 1.0 × 10-6-2.5 × 10-3 M and 2.0 × 10-5-2.5 × 10-3 M, respectively. The detection limits for EP, AC and FA were found to be 9.5 × 10-8, 9.1 × 10-7and 9.8 × 10-6 M, respectively.

Selective electrochemical sensor for folic acid at physiological pH using ultrathin electropolymerized film of functionalized thiadiazole modified glassy carbon electrode

This paper demonstrated the selective determination of folic acid (FA) in the presence of important physiological interferents, ascorbic acid (AA) and uric acid (UA) at physiological pH using electropolymerized film of 5-amino-2-mercapto-1,3,4-thiadiazole (p-AMT) modified glassy carbon (GC) electrode. Bare GC electrode fails to determine the concentration of FA in the presence of AA and UA due to the surface fouling caused by the oxidized products of AA and FA. However, the p-AMT film modified electrode not only separates the voltammetric signals of AA, UA and FA with potential differences of 170 and 410 mV between AA-UA and UA-FA, respectively but also shows higher oxidation current for these analytes. The p-AMT film modified electrode displays an excellent selectivity towards the determination of FA even in the presence of 200-fold AA and 100-fold UA. Using amperometric method, we achieved the lowest detection of 75 nM UA and 100 nM each AA and FA. The amperometric current response was increased linearly with increasing FA concentration in the range of 1.0 x 10(-7)-8.0 x 10(-4)M and the detection limit was found to be 2.3 x 10(-10)M (S/N=3). The practical application of the present modified electrode was successfully demonstrated by determining the concentration of FA in human blood serum samples.