Ceric Ammonium Sulphate Research Articles

Polyethylene Glycols Catalyzed Reaction of Catechol and Resorcinol with Cerium Ammonium Sulfate in the Aqueous Medium: Kinetic and Mechanistic Study

Polyethylene Glycols Catalyzed Reaction of Catechol and Resorcinol with Cerium Ammonium Sulfate in the Aqueous Medium: Kinetic and Mechanistic Study

The Catalytic Influence of Polymers and Surfactants on the Rate Constants of Reaction of Maltose with Cerium (IV) in Acidic Aqueous Medium

Kinetics of the reaction of maltose with cerium ammonium sulfate were analyzed spectrophotometrically by observing the decrease of the absorbance of cerium (IV) at 385 nm in the presence and absence of polyethylene glycols (600, 1500, and 4000) and polyvinylpyrrolidone (PVP), in addition to anionic micelles of sodium dodecyl sulfate (SDS), cationic micelles of cetyltrimethylammonium bromide (CTAB) and non-ionic micelles of Tween 20 surfactants. Generally, there is little literature about using the polymers (PEGs and PVP) as catalysts in the oxidation-reduction reactions. Therefore, the major target of this work was to investigate the influence of the nature of polymers and surfactants on the oxidation rates of maltose by cerium (IV) in acidic aqueous media, as well as employing the Piszkiewicz model to explain the catalytic effect. The kinetic runs were derived by adaptation of the pseudo first-order reaction conditions with respect to the cerium (IV). The reaction was found to be first-order with respect to the oxidant and fractional-order to maltose and H2SO4. The reaction rates were enhanced in the presence of polymer and micellar catalysis. Indeed, the surfactants were found to work perfectly close to their critical micelle concentrations (CMC). Electrostatic interaction and H-bonding appear to play an influential role in binding maltose molecules to polymer/surfactant micelles, while oxidant ions remain at the periphery of the Stern layer within the micelle.

Differential electrolytic potentiometric titration of vitamin C in pharmaceutical preparations

The application of direct current differential electrolytic potentiometry for the aqueous titration of vitamin C has been investigated. The reaction of vitamin C with Ce (IV) is fast enough to permit its direct titration in 0.09 M sulfuric acid media. Cerium ammonium sulfate was used as a titrant and a couple of platinum electrodes as an indicating system. Titration curve shapes obtained are almost symmetrical with sharp peaks. The optimum current density was found to be 0.65 μA cm-2. The procedure was applied successfully to the determination of vitamin C in commercial tablets, capsules as well as in juice in the concentrations of 0.02∼10 ppm. The results of this study were favorably compared statistically with those obtained with official methods.

Spectrophotometric method for the determination of benzocaine by cerium ammonium sulphate with promethazine hydrochloride in pure and phar-maceuticals preparation

Easy, the accurate, sensitive spectrophotometric method used to determine Benzocaine in a pure and pharmaceutical preparation. The proposed method depends on using Promethazine hydrochloride as a reagent. Where it depends on oxidative coupling reaction of benzocaine by cerium ammonium sulphate with promethazine hydrochloride in the presence of hydrochloric acid to form green dye product, lmax 615 nm. Beers law is obeyed in the concentration of (5 –300 µg.ml-1). The molar absorptivity is (1.77 * 10 3) L.mol -1.cm-1, a sandal sensitivity of (0.0098) µq.cm-2 and RSD (± 0.56 %). The method gave a successful determination for benzocaine in a pharmaceutical preparation.

Spectrophotometric determination of butylated hydroxyanisole in pure form and cream formulation via an oxidation–reduction reaction

Abstract Three simple, rapid, and reproducible spectrophotometric methods have been developed for the quantitative determination of butylated hydroxyanisole (BHA) in pure form and cream products. The proposed methods are based on the oxidation of the BHA in acidic medium then a known concentration of a dye was added and the unreacted oxidant was estimated using UV–Vis spectrophotometer. Method (1) is based on the oxidation of the BHA by potassium permanganate (1 × 10−3 M KMnO4, 0.6 mL) in the presence of sulfuric acid (2 M H2SO4, 0.4 mL). Then a certain amount of methylene blue (MB, 1 × 10−3 M, 0.4 mL) dye was added to the previous mixture after oxidation to reduce the unreacted oxidant. While in method (2), the oxidation of the BHA is made by cerium ammonium sulfate (CAS, 0.75 mg mL−1, 1.5 mL) in the presence of sulfuric acid (2 M H2SO4, 0.5 mL) and adding certain amount of amaranth dye (AM, 1 × 10−3 M, 0.7 mL) after oxidation to reduce the unreacted oxidant. On the other hand, n-bromosuccinimide (NBS, 5.62 × 10−4 M, 0.8 mL) is used in method (3) for oxidation of BHA in the presence of hydrochloric acid (1.0 M HCl, 0.8 mL) and methyl orange dye (MO, 1 × 10−3 M, 0.8 mL) is added after oxidation process to reduce the unreacted oxidant. For the three methods the optimum sequence of addition of the reagents was crucial and it was BHA-acid-oxidant-dye. Potassium bromide (1%, 0.6 mL) has a significant influence on the method (3) but for the others it has not. Beer's law was obeyed in the concentration range of 2.0–40, 5.0–110, 4.0–60 µg mL−1 for method (1), (2), and (3), respectively. The molar absorptivity values were found to be 4.371 × 103, 1.616 × 103 and 1.434 × 103 L mol−1 cm−1 for methods (1), (2), and (3), respectively. The proposed methods were applied for the determination of BHA in pure form and cream samples

One pot three-component synthesis of 5-substituted 1H-tetrazole from aldehyde

A versatile, robust and efficient strategy for the synthesis of vast range of highly functionalized 5-substituted 1H-tetrazole derivatives by using one pot three-component synthesis from various aldehydes, hydroxylamine hydrochloride and sodium azide in presence of a catalytic amount of ceric ammonium sulphate, a non toxic, easily available, inexpensive, unexplored and reusable catalyst is reported. This one-pot synthesis has several advantages such as mild reaction conditions, shorter reaction time, low catalyst loading, good to moderate yields and functional group tolerance making this methodology practically feasible. The synthesized compounds were characterized by 1H NMR, 13C NMR and HRMS.

Mesoporous cerium-doped titania for the photocatalytic removal of persistent dyes

Mesoporous titanium dioxide was prepared by Evaporation Induced Self Assembly (EISA) method from titanium isopropoxide as precursor, and cetyl-trimethyl-ammonium bromide as surfactant. This sample was doped with cerium oxide by incipient wetness impregnation (IWI), using cerium ammonium sulfate. Two other samples of mesoporous TiO2 doped with cerium oxide were prepared by EISA, using cerium ammonium sulfate and cerium nitrate as precursors. The samples were calcined at 773, 873 and 973K to remove the templating surfactant. The powder XRD characterization indicated the formation of anatase structure for all the calcination temperatures. The investigation of the porous structure by pure nitrogen adsorption at 77K (BET method) showed that the samples had specific surface areas between 25 and 190m2g−1 and free pore volumes of 0.15–0.35cm3g−1, depending strongly on the nature of the dopant and the preparation procedure. The band gap values of the materials deduced by UV-DR spectroscopy were situated between 2.35–2.93eV. The photocatalytic tests indicated yields of up to 72% for Rhodamin 6G decolorization under UV irradiation. The photocatalytic performances of the different samples were correlated to the results of XPS spectra, the best behavior being due to the synergetic effect of Ce (III), Ce (IV) and Oα species, involved in HO radicals obtaining.

Method validation and determination of total iodine in seaweed bathwater

Abstract Seaweeds are a well-known natural source of iodine, although the quantity present varies depending on species, geographical location and season. Traditional seaweed baths contain hot water and seaweed but to date this bathwater matrix has not been studied. The objective of this study was to validate and apply the classical spectrophotometric Sandell-Kolthoff (SK) method for the analysis of total iodine in simulated seaweed bathwater. The principle of the method is based on the catalytic activity of iodide in the reduction of ceric ammonium sulphate being directly proportional to its concentration in the sample. Linear working range was from 30 μg l-1 to 300 μg l-1 iodine. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 9 μg l-1 and 29 μg l-1, respectively. The intra-assay repeatability indicated a mean coefficient of variation (CV) <2.5%. Inter-assay precision over 7 days indicated a CV of 6.7%. Recovery ranged from 87% to 114%. Addition of seaweed to simulated bathwater results in an increase in iodine which was found to be dependent on the length of contact time and on the temperature, with higher amounts released at longer immersion times and higher temperatures. The data confirms that traditional seaweed baths containing Fucus serratus stimulate the release of iodine into bathwater.

Novel Spectrophotometric Methods for the Determination of Selegiline Hydrochloride in Bulk and Its Pharmaceutical Preparation

A simple and highly selective spectrophotometric method has been developed for the determination of selegiline hydrochloride in bulk and formulations. Method A is based on the oxidation of 3-methyl-2-benzothiazolinone hydrazone in the presence of ceric ammonium sulphate, followed by its coupling reaction with drug to form a colored product having λmax of 629 nm. Method B is based on the coupling reaction of drug with 4-aminoantipyrine to give a new ligand that reacts with copper(II) to give intense bluish red colored chelate which is measured at 539 nm. Beer’s law is obeyed in the range of 10.00–85.00 μg mL−1 with molar absorptivity of 0.98×104 for method A and 20.00–120.00 μg mL−1 with molar absorptivity of 0.94×104 for method B. The optimum reaction condition and the analytical parameters are evaluated. The results obtained indicate that the methods are free from interference of the ingredients; thus they are successfully applied to pharmaceutical formulations.

Oxidation of clindamycin phosphate by cerium(IV) in perchloric acid medium – A kinetic and mechanistic approach

Methyl 7-chloro-6,7,8-trideoxy-6-[(2S,4R)-1-methyl-4-propylpyrrolidine-2-carboxamido]-1-thio-1-threo-D-galactooctapyranoside monohydrochloride, commonly called clindamycin phosphate(CYN-P) used largely as an antibiotic for the treatment of serious infections caused by susceptible Gram-positive bacteria and an-aerobic bacteria was oxidized by using Ceric ammonium sulphate (Ce(IV)) in perchloric acid medium. Progress of the reaction was followed by measuring the decrease in absorbance of ceric ammonium sulphate at 360nm. The reaction was found to be first order each in [CYN-P] and [Ce(IV)]. Order in [HClO4] was calculated as 0.8. The reactive species of Ce(IV) appears to be H3Ce(SO4)4−. Stoichiometry of the reaction was found to be 2:1 of [Ce(IV)]:[CYN-P]. Initially added product did not alter the rate of reaction. A free radical mechanism was proposed, and rate law was derived and verified. The activation parameters, ΔH≠, ΔS≠, ΔG≠ and log A were found to be 54.7kJmol−1, −117JK−1 mol−1, 103kJmol−1 and 7, respectively.

Microtitrimetry by controlled current potentiometric titration

The classical methods of titration require large volumes of chemicals. Microtritimetry is the method of choice since it utilizes small quantities of chemicals and yields less waste compared to other conventional methods. Thus it benefits both the analytical chemists and the environment. In this communication, microtitrimetry is performed by employing the technique of differential electrolytic potentiometry for the location of the end point. Oxidation-reduction titration using platinum electrodes is described. For the first time the endpoint for a sample of 1.0 μL of 0.10 M Fe(II) has been located by titration using a solution of Ce(IV). The optimum conditions such as volume of cerium ammonium sulfate added, current applied to polarize the electrodes in case of dc controlled current potentiometric titration (CCPT). The effect of changing the percentage bias of the square wave used to polarize the electrodes on the differential peak in case of ac CCPT has been investigated. The precision of this microtitrimetric method is also reported.

Optimized Thin Layer Chromatographic Method for Screening Pharmaceutically Valuable Alkaloids of Catharanthus roseus (Madagascar Periwinkle)

The aerial parts of Catharanthus roseus (C. roseus) plant have been known to contain many important alkaloids such as Vincristine, Vinblastine, Vindoline and Ajmalicine which are of interest to this study. Ajmalicine has also been found in abundance in the roots of this medicinal plant. The main objective of this study was to screen a methanolic extract of C. roseus for the presence of pharmaceutically valuable alkaloids using previously optimized conditions established in our laboratory set up.This methanolic extract was further purified for specific alkaloids present using modified Shams et al. (2009) method I extraction procedure. Extracts of C. roseus have been subjected to optimum conditions before and after Thin layer Chromatography which was performed in a trough chamber of 10 cm x 10 cm area saturated with Ethyl acetate: Benzene: Methanol: 25% Ammonia solution (100:5:5:3) as a developing solvent and sprayed with Cerium Ammonium Sulphate (CAS) reagent specific for the detection of alkaloids.Results have shown that the alkaloids of interest; Vincristine, Vinblastine, Vindoline and Ajmalicine could be chromatographically identified in extracts of C. roseus intact plant after individual alkaloid purification procedure. This has confirmed the anti-neoplastic and anti-hypertensive properties these alkaloids have in making the plant effective in healing cancer and high blood pressure as it was originally used by traditional people.

Synthesis and characterization of starch‐graft‐polyacrylamide copolymers and their application as filtration control agents in drilling fluid

AbstractSome starch‐graft‐polyacrylamide copolymers were prepared by the polymerization of corn starch with acrylamide in aqueous medium using a complex initiation system consisting of ceric ammonium sulphate and ammonium persulphate. The copolymers were applied to water‐based drilling fluid as filtration control agents. Their grafting parameters such as percentage of grafting, grafting efficiency, and solution viscosity (η) were investigated by using elemental analyzer and rotational viscometer. The results showed that increases in initiator concentration and reaction temperature first favored and then impeded the grafting reaction. Grafting of acrylamide onto starch increased with the increase of monomer concentration. It also increased with increasing reaction time up to a certain degree and then leveled off. For the graft copolymers, a higher percentage of grafting and higher η were beneficial in decreasing the filtrate volume of water‐based drilling fluid, even under an operating environments of 147°C and saturated salinity. A possible mechanism is proposed to interpret the improvement of fluid loss properties. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers

In Vitro Dissolution Profile of Two Commercially Available Iron Preparations

Background: Current scientific evidence indicates that anemia in pregnancy, regardless of severity, is associated with an increased risk of maternal and fetal mortality. There is little published information about the bioavailability and bioequivalence of formulations containing both iron and folic acid. However, in vitro dissolution studies can provide important information on the likely relative bioavailability of various formulations. Aim: The objective of our study was to compare the in vitro dissolution of two similar commercially available formulations of iron- and folic acid-containing supplements, Folifer® (Bialport — Produtos Farmacêuticos, S.A., Portugal) and Ferroliver® (SM Pharma c.a., Venezuela), in order to determine the in vitro availability of their iron content. Folifer® and Ferroliver® were chosen because they contained similar amounts of elemental iron. Methods: The amount of iron released from each tablet was evaluated over a 4-hour period in three dissolution media replicating gastric or intestinal juices with pH values ranging from 1.5 to 6.9. The samples were then titrated with a solution of cerium ammonium sulfate in order to calculate the amount of iron released in each specific pH condition. The percentage of dissolved iron was calculated as a cumulative frequency, using the percentage of dissolved iron at all timepoints. The dissolution similarity between the two commercially available formulations was evaluated using the f 2 statistic formula. Results: During a 4-hour dissolution test, Folifer® released 59.4mg of iron compared with 48.5mg released by Ferroliver®. The value obtained for the similarity factor, an indicator of likely bioequivalence, was 41. Conclusion: These data suggest that Folifer® releases more iron than Ferroliver®, and that the two formulations are not equivalent in vitro. The superior dissolution of ferrous sulfate with Folifer® compared with ferrous fumarate in Ferroliver® might be responsible for the observed difference.

In Vitro Dissolution Profile of Two Commercially Available Iron Preparations

Background: Current scientific evidence indicates that anemia in pregnancy, regardless of severity, is associated with an increased risk of maternal and fetal mortality. There is little published information about the bioavailability and bioequivalence of formulations containing both iron and folic acid. However, in vitro dissolution studies can provide important information on the likely relative bioavailability of various formulations. Aim: The objective of our study was to compare the in vitro dissolution of two similar commercially available formulations of iron- and folic acid-containing supplements, Folifer® (Bialport — Produtos Farmacêuticos, S.A., Portugal) and Ferroliver® (SM Pharma c.a., Venezuela), in order to determine the in vitro availability of their iron content. Folifer® and Ferroliver® were chosen because they contained similar amounts of elemental iron.Methods: The amount of iron released from each tablet was evaluated over a 4-hour period in three dissolution media replicating gastric or intestinal juices with pH values ranging from 1.5 to 6.9. The samples were then titrated with a solution of cerium ammonium sulfate in order to calculate the amount of iron released in each specific pH condition. The percentage of dissolved iron was calculated as a cumulative frequency, using the percentage of dissolved iron at all timepoints. The dissolution similarity between the two commercially available formulations was evaluated using the f2 statistic formula.Results: During a 4-hour dissolution test, Folifer® released 59.4mg of iron compared with 48.5mg released by Ferroliver®. The value obtained for the similarity factor, an indicator of likely bioequivalence, was 41. Conclusion: These data suggest that Folifer® releases more iron than Ferroliver®, and that the two formulations are not equivalent in vitro. The superior dissolution of ferrous sulfate with Folifer® compared with ferrous fumarate in Ferroliver® might be responsible for the observed difference.

Spectrofluorimetric and Spectrophotometric Stability‐Indicating Methods for the Analysis of Veralipride in Presence of Its Degradants and in Spiked Human Plasma

AbstractSpectrofluorimetric and spectrophotometric stability‐indicating methods were developed and validated for analysis of veralipride (Ver) in presence of its hydrolytic and oxidative degradants. The spectrofluorimetric method was based on direct measurement of the intrinsic fluorescence of Ver at 366 nm after excitation at 299 nm using sodium lauryl sulfate (SLS) as micelle enhancer. The fluorescence intensity plot was linear over the concentration range 1.0–10.0 µg·mL−1. The high sensitivity of the method allowed its successful application to the analysis of Ver in spiked human plasma. Two other methods were developed. They are based on the oxidative coupling reaction of Ver with 3‐methyl benzothiazolin‐2‐one hydrazone (MBTH) hydrochloride in presence of ceric ammonium sulphate in an acidic medium. The first method depends on spectrophotometric measurement of the stable green colored oxidative coupling product at 660 nm. The different experimental parameters affecting the reaction were optimized. Linearity range is 10.0–100.0 µg·mL−1. The second method depends on a fluorescence quenching effect of Ver on the fluorescence of Ce3+. The difference in fluorescence intensity was measured at 380 nm after excitation at 300 nm. This method is applicable over the concentration ranges 0.25–2.50 µg·mL−1. The methods were validated according to the ICH guidelines. They were successfully applied for the analysis of Ver in drug substance, drug product and in laboratory prepared mixtures containing different percentages of hydrolytic and oxidative degradants.

A robust method for testing urinary iodine using a microtitre robotic system

Project Iodine deficiency disorders are due to inadequate thyroid hormone production and 2 billion individuals worldwide are estimated to have insufficient iodine intake. Laboratory assessment methods include urinary iodine (UI) concentration, blood FT3, FT4, TSH and Thyroglobulin. The aim of this study was to set up a robust method for testing urinary iodine using a microtitre robotic system. Procedure The UI method described is based on the Sandell–Kolthoff reaction, which utilizes the catalytic role of iodine in the reduction of ceric ammonium sulphate in the presence of arsenious acid. This method was automated for use on microtitre robotic system. Results The method was compared with the currently employed manual Sandell–Kolthoff reaction method in our laboratory as reference. The two methods correlated well using weighted Deming regression analysis (slope = 1.066, intercept = 6.5, r = 0.994; n = 211). Interassay and intraassay variations were similar to the reference method, but cost analysis indicated a large reduction in costs related to increased throughput, and reduced consumables and labour. Conclusions We have successfully adapted UI testing to an automated method, permitting cheaper, faster and robust screening of large numbers of patients and populations. The described protocol can be used on different microtitre robotic systems permitting up to 372 patient samples per run for 4 microtitre plate systems.

Quality assessment of some brands of vitamin C (ascorbic acid) tablets marketed in Uyo, Nigeria

The quality of some brands of vitamin C tablets marketed in the city of Uyo, Nigeria was assessed. All the ten samples passed the uniformity of weight and disintegration time tests as specified in the British Pharmacopoeia andUnited States Pharmacopoeia for effervescent, uncoated, dispersible tablets. However, the titrimetric evaluations for the content of active ingredient showed that seven samples contained a chemical equivalent of ascorbic acid withinthe limits of official specification. Finally, the equivalence point (end-point) was very sharp and attained faster when ceric ammonium sulphate was used as the titrating reagent.

New reagents for the spectrophotometric determination of ranitidine hydrochloride

A new spectrophotometric method is proposed for the assay of ranitidine hydrochloride (RNH) in bulk drug and in its dosage forms using ceric ammonium sulphate (CAS) and two dyes, malachite (MAG) green and crystal violet (CV) as reagents. The method involves the addition of a known excess of ceric ammonium sulphate to ranitidine hydrochloride in acid medium, followed by the determination of unreacted CAS by reacting with a fixed amount of malachite green or crystal violet and measuring the absorbance at 615 or 582 nm respectively against the reagent blank. The Beer’s law is obeyed in the concentration range of 0.4-8.0 μg/ml of ranitidine hydrochloride (RNH) for RNH-MAG system and 0.2-1.6μg/ml of ranitidine hydrochloride for RNH-CV system. The molar Absorptivity, Sandell’s sensitivity for each system were calculated. The method has been successfully applied to the determination of ranitidine hydrochloride in pure and dosage forms.

New reagents for the spectrophotometric determination of ranitidine hydrochloride

A new spectrophotometric method is proposed for the assay of ranitidine hydrochloride (RNH) in bulk drug and in its dosage forms using ceric ammonium sulphate (CAS) and two dyes, malachite (MAG) green and crystal violet (CV) as reagents. The method involves the addition of a known excess of ceric ammonium sulphate to ranitidine hydrochloride in acid medium, followed by the determination of unreacted CAS by reacting with a fixed amount of malachite green or crystal violet and measuring the absorbance at 615 or 582 nm respectively against the reagent blank. The Beer’s law is obeyed in the concentration range of 0.4-8.0 μg/ml of ranitidine hydrochloride (RNH) for RNH-MAG system and 0.2-1.6μg/ml of ranitidine hydrochloride for RNH-CV system. The molar Absorptivity, Sandell’s sensitivity for each system were calculated. The method has been successfully applied to the determination of ranitidine hydrochloride in pure and dosage forms.