Acid In Pharmaceutical Samples Research Articles

Quantification of alpha-lipoic acid in pharmaceutical samples using Pd(II) catalyzed ligand substitution reaction in SLS micellar medium

Quantification of alpha-lipoic acid in pharmaceutical samples using Pd(II) catalyzed ligand substitution reaction in SLS micellar medium

Determination of alpha-lipoic acid in pharmaceutical samples using inhibitory kinetic approach in SLS micellar medium

Determination of alpha-lipoic acid in pharmaceutical samples using inhibitory kinetic approach in SLS micellar medium

Solid-phase extraction of folic acid from pharmaceutical formulations using modified magnetic iron oxide nanoparticles

ABSTRACT. A new analytical approach was suggested for the extraction and determination of folic acid in pharmaceutical samples using solid-phase microextraction. Magnetic iron oxide nanoparticles modified with sodium dodecylbenzene sulfonate (Fe3O4@SDBS) were used for the adsorption of folic acid (FA) from an aqueous solution and determined spectrophotometrically at λmax of 365 nm. The chemical and physical conditions that may affect the efficiency of extraction were studied and optimized, such as the pH of the solution, surfactant and adsorbent amount, extraction time, and desorption factors. A good linearity range of 0.2-6 μg/mL with correlation coefficient higher than 0.999 and limit of detection of 0.08 μg/mL were obtained, in addition to high extraction efficiency of 98% and enrichment factor 15. The method exhibited good accuracy and precision with recoveries ranged 98-102% and intraday precisions of best than 3.5% at all concentrations. The method was successfully applied for the determination of folic acid in pharmaceutical samples within a limited separation time.
 
 KEY WORDS: Folic acid, MNPs, Extraction, SDBS, Spectrophotometry, Solid phase extraction
 
 Bull. Chem. Soc. Ethiop. 2022, 36(2), 291-302. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i2.4

Determination of Salicylic Acid Using a Highly Sensitive and New Electroanalytical Sensor

Background:A drug sensor (salicylic acid, in this case) was designed and made up of this research. The senor was made by modification of paste electrode (MPE) with CuO-SWCNTs and 1-hexyl-3-methylimidazolium chloride (HMICl). The MPE/CuO-SWCNTs/HMICl showed catalytic activity for the oxidation signal of salicylic acid in phosphate buffer solution.Methods:Electrochemical methods were used as a powerful strategy for the determination of salicylic acid in pharmaceutical samples. Aiming at this goal, carbon paste electrode was amplified with conductive materials and used as a working electrode.Results:The MPE/CuO-SWCNTs/HMICl was used for the determination of salicylic acid in the concentration range of 1.0 nM – 230 µM using differential pulse voltammetric (DPV) method. At pH=7.0, as optimum condition, the MPE/CuOSWCNTs/HMICl displayed a high-quality ability for the determination of salicylic acid in urine, pharmaceutical serum, and water samples.Conclusion:The MPE/CuO-SWCNTs/HMICl was successfully used as a new and high performance working electrode for the determination of salicylic acid at a nanomolar level and in real samples.

A new spectrofluorimetric method for the determination of ascorbic acid with bromocresol purple in pharmaceutical samples

Based on the interaction between ascorbic acid and bromocresol purple, a new simple, straightforward, and quick method for the quantification of ascorbic acid is proposed. The procedure is based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of bromocresol purple in the reaction between ascorbic acid and bromocresol purple in phosphate buffer solution (pH 6). The reduction of bromocresol purple fluorescence intensity is detected at 641 nm, while excitation occurs at 318 nm. The linear relationship between the reduced fluorescence intensity of bromocresol purple and the concentration of ascorbic acid is in the range 4.65 × 10–5 to 4.65 × 10–6 mol L−1 (R2 = 0.9964), with the detection limit of 8.77 × 10–7 mol L−1 and quantification limit of 2.35 × 10–5 mol L−1. The findings in this study further show that the new method provides good precision and repeatability, as well as satisfactory recovery values in terms of accuracy. The new method is tested on fifteen samples with different amounts of ascorbic acid and additional components. The effects of interfering components such as citrus bioflavonoids, citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The effects of interfering components such as citrus bioflavonoids (routine and hesperidin), citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The results of iodometric titration point out that the new method is effective for the determination of ascorbic acid in pharmaceutical samples.Article HighlightsA new spectrofluorimetric method for determination of ascorbic acid in pharmaceutical samples using bromocresol purple.Determination of optimal parameters for ascorbic acid determination in a variety of pharmaceutical samples.Examination of the influence of additional substances in the pharmaceutical samples on the analysis.

Functional Co3O4 nanostructure-based electrochemical sensor for direct determination of ascorbic acid in pharmaceutical samples

Functional Co3O4 nanostructure-based electrochemical sensor for direct determination of ascorbic acid in pharmaceutical samples

Simultaneous Determination of Trace Mefenamic Acid in Pharmaceutical Samples via Flow Injection Fluorometry

Mefenamic acid belongs to non-steroidal anti-inflammatory drugs that are used widely for the treatment of analgesia. Our aim from this study is to establish a new assay for the quantitative determination of mefenamic acid (MFA) in the pharmaceutical sample by two sensitive and rapid flow injection-fluorometric methods. A homemade fluorometer was used in fluorescence measurements, which using solid-state laser diode 405 and 532 nm as a source, combined with a continuous flow injection technique. The first method depends on the effect of MFA on calcein blue (CLB) fluorescence at 405 nm. Another method is a study of rhodamine-6G (Rh-6G) fluorescence after adding MFA, and recording at 532 nm. Optimum parameters as fluorescent dye concentration, basic medium, flow rate, sample volume, purge time, and delay coil have been investigated. The dynamic range of MFA was 0.2 to 2 mmol.L-1; 0.5 to 2.3 mmol.L-1 with linearity percentage (% r2) 98.92 and 99.83%, for Rh-6G and CLB, respectively. Limit of detection at a minimum concentration in calibration curve 189.34 and 199.89 ng/sample, for Rh-6G and CLB, respectively. The comparison of developed methods with the classical method (UV-vis spectrophotometry) was achieved. The proposed methods were successfully applied for the determination of MFA in the pharmaceutical samples and can be used as an alternative method.

ZnO nanoparticles modified sensor for the electroanalysis of thiosalicylic acid

Abstract A nano level detection of thiosalicylic acid and its analysis by sensing method has been developed at zinc oxide nanoparticles modified glassy carbon electrode by employing voltammetric techniques in pH 3.0. The modified sensor was subjected to test the influence of parameters like pH, accumulation time for thiosalicylic acid drug was studied by employing cyclic voltammetry and scan rate, excipients, thiosalicylic acid concentration variation by using square wave voltammetry technique for quantitative determination in phosphate buffer. Heterogeneous rate constant value was also determined. The zinc oxide nanoparticles modified glassy carbon electrode sensor was employed for the determination of thiosalicylic acid in pharmaceutical samples. The concentration range studied in square wave voltammetry technique exhibits lower values of detection limit and quantification of thiosalicylic acid. A possible mechanism of electrochemical oxidation of thiosalicylic acid was proposed.

A highly sensitive kinetic spectrophotometric method for the determination of ascorbic Acid in pharmaceutical samples.

In this study, a new reaction system for quantitative determination of ascorbic acid was introduced. The developed method is based on inhibitory effect of ascorbic acid on the Orange G-bromate system. The change in absorbance was followed spectrophotometrically at 478 nm. The dependence of sensitivity on the reaction variables including reagents concentration, temperature and time was investigated. Under optimum experimental conditions, calibration curve was linear over the range 0.7 - 33.5 μg mL(-1) of ascorbic acid including two linear segments and the relative standard deviations (n = 6) for 5.0 and 20.0 μg mL(-1) of ascorbic acid were 1.08 and 1.02%, respectively. The limit of detection was 0.21 μg mL(-) (1) of ascorbic acid. The effect of diverse species was also investigated. The developed method was successfully applied for the determination of ascorbic acid in pharmaceutical samples. The results were in a good agreement with those of reference method.

Microelectrodes based on porphyrins for the determination of ascorbic acid in pharmaceutical samples and beverages

Different porphyrins were used for the design of seven carbon paste and seven diamond paste based microelectrodes, which were employed for the determination of ascorbic acid in pharmaceutical and beverages samples using differential pulse voltammetry (DPV). The limits of detection lie between 1.1 × 10-14and 5.1 × 10-7M while the sensitivities were between 3.07 pA/M and 1285.18 A/M. Ascorbic acid was recovered reliable from pharmaceutical and beverages samples in percentages higher than 92.00% and 91.50%, respectively. The surface of the microelectrodes can easily be renewed by simple polishing, obtaining a fresh surface ready for use in a new assay.

Microfluidic-enzymatic biosensor with immobilized tyrosinase for electrochemical detection of pipemidic acid in pharmaceutical samples

The present article describes the development of a microfluidic-enzymatic sensor with electrochemical detection for the quantification of pipemidic acid (PA), which is a synthetic quinolone used as antibacterial agent. This property of the quinolones is associated with their potential to inhibit topoisomerase II (DNA gyrase) of bacteria. PA detection in pharmaceutical samples was based in the use of tyrosinase enzyme [EC 1.14.18.1] that was immobilized on 3-aminopropyl-modified-controlled-pore glass (APCPG) packet in a central channel (CC) of the microfluidic-enzymatic device. This enzyme catalyzes the oxidation of catechol to o-benzoquinone, whose back electrochemical reduction was detected at gold electrode surface at 0 V vs. Ag/AgCl. Thus, when PA was added to the solution, this piperazine-containing compound participates in a Michael addition reaction with o-benzoquinone to form the corresponding amino-quinone derivative, as result of this interaction the peak current obtained for o-benzoquinone reduction decreased proportionally to the increase of the PA concentration. The recovery of PA from four samples ranged from 97.50% to 102.50%. This method could be used to determine the PA concentration in the range 0.02–70 μM ( r = 0.998) with a limit of detection of 18 nM. This method was successfully applied for the analysis of PA in pharmaceutical formulations.

Kinetic Spectrophotometric Determination of Ascorbic Acid in Pharmaceutical Samples by Oxidation of Ponceau 4R by Hydrogen Peroxide

AbstractA new sensitive and simple kinetic method is developed for determination of traces of ascorbic acid based on its activated effect on oxidation of trisodium‐2‐hydroxy‐1‐(4‐sulphonato‐1‐naphthylazo)naphthalene‐6,8‐disulphonato (red artificial color Ponceau 4R) by hydrogen peroxide, in the presence of Cu(II) as catalyst, in borate buffer. The reaction is followed spectrophotometrically by tracing the oxidation product at 478.4 nm within 1 min after addition of H2O2. The optimum reaction conditions are: borate buffer (pH = 11.00), Ponceau 4R (9.6·10−6 mol/L), H2O2 (2·10−2 mol/L), Cu(II) (8·10−7 mol/L) at 22 °C. Following this procedure, ascorbic acid can be determined with a linear calibration graph up to 1.76 ng/mL and a detection limit of 0.28, based on 3S criterion. The relative error ranges between 6.77‐1.66% for the concentration interval of ascorbic acid 1.76‐17.61 ng/mL. The effects of certain foreign ions upon the reaction rate were determined for an assessment of the selectivity of the method. The method was applied for determination of ascorbic acid in pharmaceutical samples, and spectrophotometric method was used like an comparative method.

Potentiometric determination of L-ascorbic acid in pharmaceutical samples by FIA using a modified tubular electrode

A flow injection system using a tubular electrode based on the redox properties of copper (II) ions occluded in EVA membrane was developed for L-ascorbic acid determination. The poly-ethylene-co-vinyl acetate (EVA 40% m/m) matrix was doped with copper (II) ions and dispersed on the surface of a graphite/epoxy tubular electrode. The electrode showed a super-Nernstian response for L-ascorbic acid concentration between 10-3 and 10-1 mol L-1 with a detection limit of 8.5×10-4 mol L-1, when 0.1 mol L-1 KH2PO4 buffer mixed with 0.1 mol L-1 hydrogen peroxide at pH 5.0 was employed as carrier. The Potentiometric-FIA system allows an analytical frequency of 120 samples per hour with a precision of 3.6%. The results obtained for ascorbic acid determination in pharmaceutical samples, without any previous treatment, were similar to those obtained by the British Pharmacopoeia method.

A simple solid phase spectrofluorimetric method combined with flow analysis for the rapid determination of salicylamide and salicylic acid in pharmaceutical samples

A new, sensitive and very simple spectrofluorimetric biparameter sensor is described for the determination of salicylamide and/or salicylic acid in pharmaceutical preparations. The method integrates the transitory retention and fluorescence detection of both compounds on Sephadex QAE A-25 resin packed into a conventional flow-through cell. A monochannel manifold with two alternative carriers is used. At pH 2.0 (first carrier) salicylic acid is selectively retained on the solid support and after developing the analytical signal it is desorbed. At pH 11.0 (second carrier) both salicylic acid and salicylamide are simultaneously and transitorily retained on the solid, the analytical signal now corresponding to both analytes. The monochromators were tuned at 260 (excitation) and 415 (emission) nm, respectively. The calibration graph for salicylamide is linear over the range 0.01 to 0.32 μg mL–1 and for salicylic acid from 0.04 to 1.0 μg mL–1 in the presence of each other. The relative standard deviation and the sampling frequency for the determination of salicylamide (0.20 μg mL–1) and salicylic acid (0.50 μg mL–1) were 1.1% and 35 h–1, and 0.9% and 45 h–1, respectively. Good results on application to individual determination or mixture resolution in pharmaceutical samples testify to the usefulness of the proposed sensor.

Indirect spectrophotometric determination of ascorbic acid in pharmaceutical samples and fruit juices

An indirect, sensitive spectrophotometric method for the assay of ascorbic acid is described. The procedure is based on the oxidation of ascorbic acid by a known excess of iodate in the presence of acid. The unreacted iodate is utilized for hydroxylamine oxidation to generate nitrite. Sulfanilic acid is diazotized by the nitrite formed and the resulting diazonium ion is coupled with N-(1-naphthyl)ethylenediamine dihydrochloride to form an azo dye which shows an absorption maximum at 540 nm. The absorbance is found to decrease linearly with increasing concentration of ascorbic acid, which is corroborated by the calculated correlation coefficient value of –0.9994. The system obeys Beer's law for 0–40 µg of ascorbic acid in an over-all aqueous volume of 10 ml. The molar absorptivity and RSD were calculated to be 2.1 × 104 l mol–1 cm–1 and 2.5%(n= 10), respectively. The proposed method was applied successfully to the determination of ascorbic acid in pharmaceutical preparations and fresh fruit juices. The reliability of the assay was established by parallel determination by the standard iodimetric method and recovery studies.

Spectrophotometric determination of ascorbic acid in pharmaceuticals by background correction and flow injection

Background correction has been shown to be an effective and indispensable modification in the spectrophotometric determination of ascorbic acid. The decomposition of ascorbic acid in pharmaceutical samples was carried out by incubation with sodium hydroxide to give products that were insensitive to ultraviolet light. The rapid oxidation in air of ascorbic acid, especially in dilute solutions, was avoided by the use of the flow injection principle for spectrophotometric determination and by employing a carrier stream of an anti-oxidizing nature consisting of 6 micrograms ml(-1) of 2-mercaptoethanol in 0.25% sulphuric acid. The optimized method with a single channel manifold made use of a carrier stream flow rate of 1.1 ml min(-1), an injection volume of 50 microl, a delay coil of 50 cm (0.5 mm i.d.) and detection at 245 nm. The throughput was at least 180 injections h(-1). The proposed flow injection method yielded results for the analysis of 0-20 micrograms ml(-1) of ascorbic acid that were 99-102% (relative standard deviation 0.6% or better) in agreement with those produced by comparable methods involving titration with iodine, chloranil or 2,6-dichlorophenolindophenol [4-(2,6-dichloro-4-hydroxyphenylimino)cyclohexa-2,5-dieno ne], and high-performance liquid chromatography. When the agreement was not good (as low as 14% with respect to the method being compared), this was traced to the presence of substances which are known to interfere in one or other of the methods of comparison.