Ascorbic Acid In Pharmaceutical Preparations Research Articles

Development of silver nanoparticles based on the method using quince seed mucilage for ascorbic acid determination.

Nanoparticles are used in various fields such as chemistry, pharmacy, biotechnology, and food science since they provide higher sensitivity than traditional optical detection methods. Recently, synthesis of nanomaterials using green chemistry has become popular. Many phytochemical components are used in the synthesis of nanoparticles, including vitamins, proteins, polysaccharides, glycosides, essential oils and phenolic compounds. A novel green nanotechnology-based method using quince seed mucilage (QSM) was designed for the determination of ascorbic acid in pharmaceutical preparations. QSM, a natural polysaccharide, was used as a bioreducing and stabilizing reagent in the proposed silver nanoparticle (SNP)-based method. In the first stage of the developed method, silver(I) is reduced to silver(0) via QSM and spherical, homogeneous SNPs were prepared (QSM-SNPs). In the second stage of the developed method, SNPs nuclei were enlarged with the addition of ascorbic acid. The developed method was validated by performance parameters (linearity, recovery, and precision). Ascorbic acid determination was performed by measuring increase in absorbance at 420 nm. The limit of detection and limit of quantification for ascorbic acid were, respectively, found to be at 0.27 and 0.90 μM. The QSM-SNP-based method was successfully applied to effervescent tablets containing ascorbic acid. The standards of the excipients frequently used in pharmaceutical preparations did not interfere with the developed method. The developed QSM-SNP-based method satisfies the requirements of green nanotechnology. The developed QSM-SNP-based method is simple, fast, eco-friendly and low-cost.

Determination of Ascorbic Acid in Pharmaceuticals and Biological Fluids by the Quenching of Europium Luminescence

Here we present a novel strategy for the quantification of ascorbic acid (AA) (vitamin C). The developed method is based on the quenching effect produced by AA on the time-resolved luminescence signal of europium ions using excitation and emission wavelengths of 388 nm and 617 nm. The method presents a linear dynamic range from 0.2 to 2 µg mL−1 with a detection limit of 0.06 µg mL−1 and a relative standard deviation lower than 6%. The method was applied to the determination of AA in pharmaceutical preparations, human serum and human urine. The obtained results in pharmaceuticals were compared with a reference method; the recovery yields were close to 100% in all cases. The accuracy of the method was statistically assessed, demonstrating the suitability of this alternative method for the determination of AA in pharmaceuticals and biological samples, requiring no sample treatment except for a dilution step.

Voltammetric Determination of Ascorbic Acid in Pharmaceutical Formulations on a Boron Doped Diamond Electrode

The electrochemical behavior of ascorbic acid (AA) is studied by means of cyclic voltammetry (CVA) and square-wave voltammetry (SWVA) on a boron doped diamond electrode (BDD). The possibility of using the voltammetric response signal to determine quantitatively the concentration of AA in an aqueous solution is shown. An analytical direct correlation function for SWVA at BDD is obtained. It is shown that the detection limit for AA is 1.87 μM. The applicability of SWVA for determining the content of AA in pharmaceutical preparations is demonstrated.

High Perfarmance Liquid Chromatographic Determination of Ascorbic Acid in Pharmaceutical Preparations, Fruit Juices and Human Serum

High Perfarmance Liquid Chromatographic Determination of Ascorbic Acid in Pharmaceutical Preparations, Fruit Juices and Human Serum

Densitometric-high-performance thin-layer chromatographic estimation of diosmin, hesperidin, and ascorbic acid in pharmaceutical formulations

An attempt was made to develop and validate a simple, accurate high-performance thin-layer chromatographic (HPTLC) method for the simultaneous determination of diosmin, hesperidin, and ascorbic acid in pharmaceutical preparations. Analysis was performed on 10 cm × 20 cm aluminum-backed plates coated with 0.2 mm layers of silica gel 60 F254 (Merck, Germany). CAMAG TLC Scanner III was used for UV densitometric scanning. The used HPTLC system was found to give sharp, symmetrical, and well-resolved peaks at RF values of 0.34 ± 0.02, 0.40 ± 0.04, and 0.56 ± 0.03, and linearity was found in the ranges 100–800 ng/spot (r2 = 0.9985), 100–800 ng/spot (r2 = 0.9966), and 50–400 ng/spot (r2 = 0.9951) for diosmin, hesperidin, and ascorbic acid, respectively.

Indirect method for spectrophotometric determination of ascorbic acid in pharmaceutical preparations with 2,4,6-tripyridyl-s-triazine by flow-injection analysis

A flow-injection indirect spectrophotometric method for the determination of ascorbic acid (AA) in pharmaceutical preparations is proposed. The method is based on the reduction of iron(III) to iron(II) by the AA, and by the subsequent reaction of the produced iron(II) with 2,4,6-tripyridyl-s-triazine (TPTZ) in buffered medium (pH=3.6) to form a coloured complex (λmax=593nm). The three-line manifold with one reaction coil was used. The linear range of the method is from 0.08 to 10μM of ascorbic acid, with the detection limit 24nM of AA. The proposed method is simple, rapid (sampling rate of 180 samples per hour), sensitive and reproducible (RSD 0.8%, n=100). The proposed method is very selective, because only the reducing substances with standard (formal) potentials lower than 0.6V would have the thermodynamic predisposition to interfere in the proposed method. Tested reducing substances (thiol compounds) did not give serious errors when present at the same concentrations as the ascorbic acid. The proposed method can be applied for the determination of AA in pharmaceutical preparations, down to picomolar quantity.

Flow Injection Determination of Vitamin C in Pharmaceutical Preparations by Differential Electrolytic Potentiometry

Differential electrolytic potentiometry (DEP) was coupled with Flow injection analysis (FIA) technique for the determination of ascorbic acid in pharmaceutical preparations. Platinum electrodes were used as an indicating system to follow the oxidation of vitamin C with either potassium iodate, or potassium permanganate in an acidic medium. Univariate method was employed to optimize the variables such as the current density, the flow rate, the concentrations of the oxidants and the sulfuric acid. A current density of 40 μAcm -2 and a flow rate of 25 μlsec -1 were found to be optimum. The optimum concentrations of iodate and permanganate were 8.35 mM and 0.11 mM respectively. On using iodate as an oxidant the method showed a linear range of 12-130 μgml -1 , a detection limit of 9 μgml -1 and R2 of 0.999. In case of permanganate a linear range of 18-36 μgml -1 , a detection limit of 11 μgml -1 and an R2 of 0.996 were obtained. The procedure was applied successfully to the determination of vitamin C in commercial tablets. The results of this study were found to be statistically comparable with those obtained by official methods.

Electrocatalytic Determination of Ascorbic Acid at the Surface of 2,7‐Bis(ferrocenyl ethyl)fluoren‐9‐one Modified Carbon Paste Electrode

AbstractA chemically modified carbon paste electrode with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one (2,7‐BFEFMCPE) was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The diffusion coefficient (D=1.89×10−5 cm2 s−1), and the kinetic parameter such as the electron transfer coefficient, α (=0.42) of ascorbic acid oxidation at the surface of 2,7‐BFEFMCPE was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 300 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak currents show a linear dependence on the ascorbic acid concentration and linear analytical curves were obtained in the ranges of 8.0×10−5 M–2.0×10−3 M and 3.1×10−5 M–3.3×10−3 M of ascorbic acid with correlation coefficients of 0.9980 and 0.9976 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2δ) were determined to be 2.9×10−5 M and 9.0×10−6 M with cyclic voltammetry and differential pulse voltammetry, respectively. This method was also examined for determination of ascorbic acid in pharmaceutical preparations.

Electrochemical Behavior of Chloranil Chemically Modified Carbon Paste Electrode. Application to the Electrocatalytic Determination of Ascorbic Acid

AbstractA p‐chloranil modified carbon paste electrode was constructed and the electrochemical behavior of this electrode was studied in the aqueous solution with different pH. From the E1/2–pH diagram for this compound the values of formal potential E0' and pKa of some different redox and acid‐base couples depending on the solution pH were estimated. The diffusion coefficient, D, value for p‐chloranil was estimated 1.5×10−7 cm2 s−1. It has been shown by direct current cyclic voltammetry and double potential step chronoamperometry, that this p‐chloranil incorporated carbon paste electrode, can catalyze the oxidation of ascorbic acid in the aqueous buffered solution. Under the optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 325 mV less positive than that at an unmodified carbon past electrode. The catalytic oxidation peak currents was linearly dependent on the ascorbic acid concentration and a linear calibration curve was obtained in the range of 7×10−5 M–4×10−3 M of ascorbic acid with a correlation coefficient of 0.9998. The limit of detection (3σ) was determined as 3.5×10 −5 M. This method was used as simple, selective and precise voltammetric method for determination of ascorbic acid in pharmaceutical preparations.

Simultaneous voltammetric detection of ascorbic acid and uric acid at a carbon-paste modified electrode incorporating thionine–nafion ion-pair as an electron mediator

The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) at the surface of a carbon-paste electrode modified with incorporate thionine–nafion ion-paired was thoroughly investigated. The results show the presence of nafion inside the matrix of modified electrode, because of the effective ion-pairing and hydrophobic interactions, significantly enhances the stability of thionine as an electron mediator inside the modified electrode. A high reproducibility in voltammetric response to analyte species results because of this enhancement. The cyclic voltammetric studies using the prepared modified electrode show the best electrocatalytic property for the electro-oxidation of AA and noticeable decrease in anodic overpotential. Although the catalytic effect is observed to some extent for UA, the property cannot be seen for other biologically reducing agents such as cysteine. The voltammetric studies using the thionine–nafion modified electrode show two well-resolved anodic peaks for AA and UA, revealing the possibility of the simultaneous electrochemical detection of these compounds in the presence of biological thiols. The detection limits of 5 × 10 −8 and 5 × 10 −7 M were obtained in differential pulse voltammetric (DPV) measurements for UA and AA, respectively. Spectrophotometric investigations were used to confirm the selective catalytic effect of thionine in oxidation of AA and to some extent, UA. The detection system is stable (R.S.D. for the slope of the calibration curves was less than 4% for six measurements in one month) and is of high selectivity for electro-oxidation of AA and UA in complex biological and clinical matrices. The prepared modified electrode is applied for the DPV measurement of AA in pharmaceutical preparations. Also, the electrode is used to determine UA in human urine and serum samples and recovery of the amounts of UA added to these complex samples.

A Simple and Reliable Spectrophotometric Method for the Determination of Ascorbic Acid in Pharmaceutical Preparations

In this study, a simple spectrophotometric method based on the reaction between ascorbic acid and the copper(II)–ammonia complex is presented for the determination of the vitamin C content of pharmaceutical preparations. During this reaction, ascorbic acid is oxidized and the copper(II)–ammonia complex is reduced to the copper(I)–ammonia complex, and the absorbance decrease at 600 nm (λmax for the copper(II)–NH3 complex) is measured. Stirring the final solution in the presence of air leads to the primary absorbance again being obtained, which indicates that the copper(I)–NH3 complex is quantitatively oxidized to the copper(II)–NH3 complex by O2. The linear dynamic range of the calibration curve is 0.8–6 mmol with a detection limit of 0.26 mmol. The relative standard deviation for eight repeated experiments is 2.4%, which shows that the proposed method has a good repeatability. Finally, this method was used in the analysis of the vitamin C content of different pharmaceutical preparations, such as multivitamin tablets and syrups, vitamin-C tablets and powders, and effervescent tablets. The obtained results are in good agreement with iodimetric data.

A New Simple and Accurate Turbidimetric Method for Determination of Ascorbic Acid in Pharmaceuticals and Fruits

AbstractAn accurate, simple, solvent free and inexpensive turbidimetric method is presented for the determination of ascorbic acid in pharmaceutical preparations and fruits. It needs no special reagents or precautions. In this method HgCl2 oxidizes ascorbic acid in citrate buffer at a pH of about 4 and produced Hg2Cl2 precipitate as monitored by turbidance measurements. The procedure is very simple and the experimental conditions such as temperature, ionic strength, stirring and time are not critical. High sensitivity and selectivity are two other advantages of this method. Linear dynamic range of the calibration curve is between 3–120 μg/mL with limit of detection (LOD) 1 μg/mL, which allows the ascorbic acid contents of most fruits and vegetables to be analyzed. On the other hand, the interference studies show that common compounds in real samples and colored substances have no considerable effect on the determination. Only filtration of some samples is necessary and other treatments, which are performed prior to determination of ascorbic acid by other analytical methods, are eliminated. Finally, ascorbic acid concentration in different samples is determined by the proposed method and obtained results are compared with the results of the official 2,6‐dichlorophenolindophenol or iodimetric methods and a good agreement is obtained. This method is very sensitive in comparison with iodimetry and is very fast relative to the 2,6‐dichlorophenolindophenol method.

Silver salt of N-bromo-4-methylbenzenesulfonamide as a new oxidimetric reagent

A new oxidimetric reagent, RNBrAg, where R is p-CH3C6H4SO2, is proposed for redox titrations in aqueous medium. The stability of the oxidant in aqueous medium is studied both in dark and day light for several days. Direct titration procedures have been developed for the determination of some inorganic and organic compounds using the above oxidant. The method is successfully employed for the estimation of ascorbic acid in pharmaceutical preparations. The redox potential of RNBrAg-PTS (PTS = p-toluenesulfonamide) couple has been determined at 28degrees and pH 6.92.

Automatic determination of ascorbic acid by flame atomic absorption spectrometry

A continuous flow procedure is proposed for the indirect determination of ascorbic acid based on its reducing properties. Chromium(VI) in acid medium was injected into a ascorbic acid stream, and the Cr(VI) was reduced to Cr(III). This Cr(III) formed was retained on-line, proportionally to the ascorbic acid concentration in the sample, on a poly(aminophosphonic acid) chelating resin, which is only selective for this oxidation state, while non-reduced Cr(VI) was determined by flame atomic absorption spectrometry. The proposed method allows the determination of ascorbic acid in the range 0.4–20 μg ml −1 with a relative standard deviation of 2.0% at a rate of ca. 90 samples per hour. This method has been applied to the determination of ascorbic acid in pharmaceutical preparations and fruit juices.

Spectrophotometric determination of ascorbic acid with iron(III) and p-carboxyphenylfluorone in a cationic surfactant micellar medium.

A simple and highly sensitive spectrophotometric method for the determination of ascorbic acid (AA) was established by using iron(III) and p-carboxyphenylfluorone (PCPF) in a cationic surfactant micellar medium. The apparent molar absorptivity of the proposed method, which does not require an extraction procedure, was 2.05 x 10(6) dm3 mol-1 cm-1 at 655 nm. Beer's law was obeyed in the concentration range of 0.02-0.12 microgram/cm3 for AA. The procedure was successfully applied to assays of AA in pharmaceutical preparations. It is suggested that the method is based on a coupled redox-complexation reaction in which the first step is the oxidation of AA by iron(III), and the second step includes the formations of the iron(II)-PCPF (1:2) complex and the dehydroascorbic acid-iron(III)-PCPF (1:1:2) complex.

A rapid and selective solid-phase UV spectrophotometric method for determination of ascorbic acid in pharmaceutical preparations and urine

Ascorbic acid was determined by a solid-phase UV spectrophotometry technique through the sorption of this on a dextran-type anion-exchange resin, Sephadex QAE A-25 and posterior direct measurement of its absorbance on the resin at 267 and 400 nm, packed in a 1-mm cell. The calibration graph was linear over the range 0.3–5.0 μg ml −1. The sensitivity obtained is more than 50 times higher than that of the corresponding solution method. The detection limit was 0.05 μg ml −1 and the relative standard deviation 0.74% ( n=10). This method is very rapid and highly selective for determining ascorbic acid in the presence of other species absorbing in the ultraviolet region and which are normally encountered with it. The one-step method proposed was successfully applied in the determination of ascorbic acid in pharmaceutical preparations and urine and the results were of comparable accuracy as indicated by a statistical analysis of the data, using both t- and F-tests.

Indirect spectrophotometric determination of ascorbic acid with ferrozine by flow-injection analysis

A FIA indirect spectrophotometric determination of ascorbic acid was developed using its reducing action on Fe(III) in acidic medium and following the spectrophotometric determination of the reduced iron by using sodium 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-4′,4″-disulphonate (ferrozine) as chromogenic reagent in buffered medium (pH 5.5) and monitoring the absorbance signal at 562 nm. A three-line manifold with two reaction coils was used: in the first reaction coil, ascorbic acid reduces Fe(III) to Fe(II); and in the second one, the complexation reaction is developed. The linear range of the method was 0.5–10 μg ml −1 of ascorbic acid, the detection limit being 0.028 μg ml −1. The proposed method was sensitive, rapid (sampling rate of 90 samples h −1) and reproducible (RSD 0.19%, n=10). Satisfactory results were obtained in the determination of ascorbic acid in pharmaceutical preparations, fruit juices and urine testifying the applicability of the method to real samples.

Potentiometric determination of ascorbic acid in pharmaceutical preparations using a copper based mercury film electrode

Potentiometric determination of ascorbic acid in pharmaceutical preparations using a copper based mercury film electrode

Colorimetric determination of ascorbic acid in pharmaceutical preparations and biological samples

A simple and rapid method is described for the determination of L-ascorbic acid, based on its reduction of iron (III). The iron(II) thus formed is complexed with quinaldic acid and pyridine. The absorbance is measured at 380 nm after extracting the complex into chloroform. Beer's law is obeyed over the concentration range 2.5–25 μg ml−1 ascorbic acid. The results obtained are accurate and reproducible with the standard deviation of 0.0076. The method has been applied to the analysis of pharmaceuticals and biological samples with satisfactory results.

Indirect flow-injection determination of ascorbic acid by flame atomic absorption spectrometry

A continuous-flow procedure is proposed for the indirect determination of ascorbic acid, based on its reducing properties because of the oxidation of its 1,2-enediol group. Iron(III) was injected into a 1,10-phenanthroline stream, which was mixed with a sample carrier and then with a sodium picrate solution stream. In these conditions the iron(III) was reduced to iron(II) by the ascorbic acid. Thus, the iron(II) formed reacts with 1,10-phenanthroline to form a charged red complex, which with picrate ion forms a stable red-orange uncharged ion-association complex that is adsorbed “on-line” on a non-ionic polymeric adsorbent (Amberlite XAD-4), proportionally to the ascorbic acid in the sample. The unadsorbed iron was determined by flame atomic absorption spectrometry. The proposed method allows the determination of ascorbic acid in the range 0.5–25 μg ml−1 with a relative standard deviation of 2.9% at a rate of ca. 90 samples h−1. This method has been applied to the determination of ascorbic acid in pharmaceutical preparations, fruit juices and sweets. The results obtained in the analysis are compared with those provided by the 2,6-dichloroindophenol method.