Acetate Buffer Medium Research Articles

Kinetics and mechanism of the oxidation of ethane diol and butane-2,3-diol by tetrachloroaurate(III) in acetate buffer medium

The reductivities of ethane diol and butane-2,3-diol towards tetrachloroaurate(III) in acetate buffer medium have been studied. The reaction is of first order with respect to the oxidant but of complex order with respect to the substrate. The reaction is inhibited by both H + and Cl - ions. A decrease in the dielectric constant of the medium diminishes the rate. Different thermodynamic parameters have been evaluated. The reaction appears to involve a fast pre-equilibrium with the formation of an intermediate complex between AuCl - 4 and diol and the complex then disproportionates in the rate limiting step to give the product and Au 1 .

Determination of Tellurium(IV) in Various Environmental Samples with Spectrophotometry

A rapid, simple and sensitive spectrophotometer method for the determination of traces and ultra traces of tellurium(IV) were studied. These method were based on either the oxidation of leuco methylene green (LMG) to its blue form of methylene green by tellurium in acidic medium, the formed dye shows an absorption maximum at 650 nm in acetate buffer medium (pH 3.0 to 5.0). Beer’s law were obeyed in the concentration range 0.4‐2.5 µg mL-1, having molar absorptivity and Sandal’s sensitivity of 4.9×104 L mol-1 cm-2 , and 0.0026 µg cm-2, respectively. The optimum reaction conditions and other analytical parameters were investigated to enhance the sensitivity of the present method. The tolerance limit of various ions with this method has been studied. The proposed method was applied for the analysis of tellurium in spiked, river, lake, spring, waste water samples, plant materials and soil samples. The results obtained by the proposed method were superior to the reported method. The performances of proposed methods were evaluated in terms of student’s ‘t’‐test and variance ratio ‘f’‐test which indicates the significance of proposed methods over reported methods.

Extractive spectrophotometric determination of copper(II) in water and alloy samples with 3-methoxy-4-hydroxy benzaldehyde-4-bromophenyl hydrazone (3,4-MHBBPH)

A facile, sensitive and selective extractive spectrophotometricmethod was developed for the determination of copper(II) in various water and alloy samples using a newly synthesized reagent, 3-methoxy-4-hydroxy benzaldehyde 4-bromophenyl hydrazone (3,4-MHBBPH). Copper(II) forms a orange colored complex with (3,4-MHBBPH) in acetate buffer medium (pH 4) which increases the sensitivity and the complex was extracted into chloroform. Under optimum conditions, the maximum absorption of the chloroform extract was measured at 462 nm. The Beer law was obeyed in the range of 0.20 to 4.0 ?g ml-1 of copper. The molar absorptivity and the Sandell's sensitivity of the complex were 2.0520 x 104 mol-1 cm-1 and 0.2540 ?g cm-2, respectively. The detection limit was found to be 0.0270 ?g mL-1. A detailed study of various interfering ions made the method more sensitive. The method was successfully applied for the determination of Cu(II) in water and alloy samples. The performance of the present method was evaluated in terms of Student 't' test and Variance ratio 'f ' test, which indicate the significance of the present method over reported methods.

Spectrophotometric determination of copper(II) and nickel(II) using thiosemicarbazone of citral

Tbiosemicarbazone of citral, a condensation product of industrially and ecofriendly terpenoid serve as very good analytical reagent for biologically important metal copper and nickel. The analytical properties of thiosemicarbazone of citral (CDOTSC) are described for the first time. The reagent gives brown colour complex with copper and grey colour complex with nickel in sodium acetate buffer medium of 5.6 and 2.6 respectively. The molar absorptivities of copper and nickel complexes respectively are 8.75 x 10 3 and 1.25 x 10 4 L mol -1 cm -1 . These colour reactions have been investigated for the spectrophotometric determination of copper(II) and nickel(II) in aqueous medium.

Adsorption of hexavalent chromium on manganese nodule leached residue obtained from NH 3–SO 2 leaching

Adsorption of hexavalent chromium onto manganese nodule leached residues was investigated as a possible alternative to the conventional methods of its removal from aqueous synthetic solutions. Adsorption behavior was studied as a function of time, pH, temperature, and concentration of adsorbate and adsorbent in acetic acid–sodium acetate buffer medium. Cr (VI) removal was pH dependent and was found to be of a maximum at pH 3. The applicability of the Langmuir isotherm to the present system was tested. Increased adsorption capacity with increased temperature indicates that the adsorption reaction was endothermic in nature. Based on these studies, thermodynamic parameters such as Gibbs free energy change ( Δ G 0 ), standard enthalpy change ( Δ H 0 ), and standard entropy change ( Δ S 0 ) were calculated.

Separation of Nickel and Copper by Solvent Extraction Using Di‐2 Ethylhexylphosphoric Acid‐Based Synergistic Mixture

Solvent extraction of copper(II) and nickel(II) from aqueous acetate solutions with di(2‐ethylhexyl)phosphoric acid (D2EHPA), dissolved in n‐heptan has been investigated. The extraction of Cu(II) was found to be quantitative in neutral, acetic acid, and acetate buffer media 96%, 95%, and 85% respectively. On the other hand, the extraction efficiency of Cu(II) decreases with the increase of the salt concentration in the aqueous solution. The extraction of Ni(II) in acetate buffer media is better than in neutral, 94% and 83% respectively. In addition, mechanisms of copper(II) and nickel(II) extraction have been established in neutral, acid, salt, and acetate buffer media. The results obtained are in good agreement with the speciation calculations given by the Cheaqs v. L20.1 (A Program for Calculating Chemical Equilibria in Aquatic Systems, RIVM, Bilthoven, The Netherlands). A study of the extraction kinetics of the copper‐D2EHPA system was carried out. The mass transfer resistance was found to have a significant influence on the overall rate of the extraction of copper. At first, the extraction of an equimolar mixture of these two metals (Cu2+, Ni2+) was carried out in order to determine the optimum conditions for their separation from each other by the D2EHPA. The results showed that the selective extraction of copper(II) over nickel(II) 93% and 83%, respectively takes place at pHs=5.71 using 4.8 mmol dm−3 D2EHPA in n‐heptan. Then, the same study was performed with tri‐butyl phosphate (TBP) organophosphorus co‐extractants. Synergistic effect has been observed on the yield of extraction of copper over nickel at 0.76 of TBP onto D2EHPA ratio in extractants mixture.

Studies on manganese nodule leached residues: 2. Adsorption of aqueous phosphate on manganese nodule leached residues

Adsorption of phosphate onto manganese nodule leached residues was investigated as a possible alternative to conventional methods of phosphate removal from industrial effluents. Adsorption behaviors were studied as a function of time, temperature, pH, and concentration level of adsorbate and adsorbent in acetic acid–sodium acetate buffer medium. The adsorption of phosphate follows the Langmuir adsorption isotherms. The magnitude of adsorption of phosphate in manganese nodule leached residues was compared with that in naturally occurring Mn nodule. Manganese nodule leached residues show better affinity toward phosphate adsorption.

Synthesis and characterization of a novel cross-linking complex of β-cyclodextrin- o-vanillin furfuralhydrazone and highly selective spectrofluorimetric determination of trace gallium

A novel host inclusion complex of cross-linking-polymeric-β-cyclodextrin- o-vanillin furfuralhydrazone (β-CDP-OVFH) was synthesized and characterized with IR and 1H NMR spectra to confirm its structure. A highly selective and sensitive fluorescent determination of trace amounts of gallium was proposed based on the reaction between Ga 3+ with β-CDP-OVFH in acetic acid–ammonium acetate buffer medium of pH 4.10. The maximum excitation and emission wavelengths were 392 and 499 nm, respectively. The linear range of this method was 1.5–330 ng ml −1 with a detection limit of 0.44 ng ml −1. The effect of interferences in the determination of gallium was investigated and the results showed that the same race elements such as Al 3+ and In 3+ did not interfere the determination of Ga 3+ even when their concentration is 100 times of Ga 3+, the host reagent had quite high capacity of identifying Ga 3+. This method was successfully applied to the determination of trace amounts of Ga 3+ in artificial and semiconductor samples.

Synthesis of a novel host molecule of cross-linking-polymeric-β-cyclodextrin- o-vanillin furfuralhydrazone and spectrofluorimetric analysis of its identifying cadmium

A novel host inclusion complex of cross-linking-polymeric-β-cyclodextrin- o-vanillin furfuralhydrazone (β-CDP-OVFH) was synthesized and characterized with IR and 1H NMR spectra to confirm its structure. The coordination reaction of the host reagent with Cd 2+ was studied and the optimum reacting conditions were observed carefully. A highly selective and sensitive spectrofluorimetric determination of trace amount of cadmium was proposed based on the reaction of Cd 2+ with β-CDP-OVFH in ammonia water–ammonium acetate buffer medium of pH=11.0. The molar ratio of β-CDP-OVFH to Cd 2+ was 1:1. The maximum excitation and emission wavelengths were 393 and 494 nm, respectively. The linear range of this method was from 3.0 to 500 μg l −1 with a detection limit of 0.80 μg l −1. The effect of interferences in the determination of cadmium was investigated and the results showed that the host reagent had quite high capacity of identifying Cd 2+. The proposed method was successfully applied to the determination of trace amount of Cd 2+ in mussel and tea samples.

Novel features in the oxidation of dihydroxy benzenes by 2,6-dichloroquinone-4-chloro-imide in acetic acid and sodium acetate buffer medium

Kinetics of oxidation of quinol, catechol and resorcinol by 2,6-dichloroquinone-4-chloro-imide (DCQCI) in CH 3 COOH-NaOAc system is reported. The kinetic features of ortho dihydroxy and para dihydroxy benzenes are similar.The reactions are zero order in oxidant at lower concentrations of oxidant (below 0.0005 M) and fractional order in substrate. At higher concentrations of oxidant, these two compounds exhibit first order in oxidant and fractional order in substrate leading to independence. Resorcinol exhibits different kinetic features : first order in oxidant at all concentrations and fractional order in substrate. The major products are coupling products under these conditions. Reactivity order is resorcinol > catechol > quinol. This result is novel. A mechanism is postulated to explain the observed order and a suitable rate law has been derived.

Synthesis and characterization of a novel cross-linking complex of β-cyclodextrin- o-vanillin benzoylhydrazone and its selective spectrofluorimetric determination of trace amounts of zinc

A novel host inclusion complex of β-cyclodextrin- o-vanillin benzoylhydrazone (β-CDP–OVBH) was prepared and characterized by IR and 1H-NMR spectra. A highly selective and sensitive fluorescent determination of trace amounts of zinc was proposed based on the reaction between Zn 2+ and β-CDP–OVBH in sodium hydroxide–ammonium acetate buffer medium of pH 8.3. The molar ratio of β-CDP–OVBH to Zn 2+ was 1:1.The maximum excitation and emission wavelengths were 396 and 486 nm, respectively. The linear range of this method was 2.5–500 μg l −1 with a detection limit of 0.60 μg l −1. The effect of interferences in the determination of zinc was investigated, the results showed that the host reagent had a quite high identifying capacity on Zn 2+. This method was successfully applied to the determination of trace amounts of Zn 2+ in tea and human hairs.

Capillary electrophoresis of alpha-lactalbumin in milk powders.

A quick and simple method for the extraction and analysis of alpha-lactalbumin in milk protein powders is presented, which permits accurate duty classification of commercial products as required under the U.S. Harmonized Tariff System. An acetic acid buffer medium is utilized to extract the whey proteins, which are then analyzed by capillary electrophoresis using an electrokinetic injection onto an uncoated column. The running buffer is composed of a 50 mM borate buffer at pH 8.0. The separation is rapid (<5 min) and displays good limits of detection (+/-0.01 mg mL(-1)). Overall, the method provides a simple means for extracting and analyzing alpha-lactalbumin in milk powders.

A highly sensitive spectrophotometric determination of chromium using leuco Xylene cyanol FF

A highly sensitive and selective spectrophotometric method was developed for the determination of trace amounts of chromium with leuco Xylene cynaol FF. The method is based on the oxidation of leuco Xylene cyanol FF (LXCFF) to its blue form of Xylene cyanol FF by chromium(VI) in sulphuric acid medium (pH 1.2–2.4), the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0–4.6) at 615 nm. The method obeys Beer's law in the concentration range of 0.05–0.45 μg ml −l chromium, having molar absorptivity and Sandell's sensitivity of 8.23×10 4 l mol −1 cm −l and 0.00063 μg cm −2, respectively. All the variables were studied in order to optimise the reaction conditions. The developed method has been successfully applied to the determination of chromium in steels, pharmaceutical samples, industrial effluents, natural water, and soil.

A New Spectrophotometric Method for the Determination of Cerium Using Leuco Disulphine Blue

A new, simple, highly sensitive spectrophotometric method for the determination of trace amounts of cerium(IV) is described. The method is based on the oxidation of leuco disulphine blue (LDSB) to its blue form of disulphine blue by Ce(IV) in a sulfuric acid medium (pH 1.3–3.0); the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0–4.8) at 635 nm. The color system obeys Beer's law in the concentration range from 0.5 to 5.5 μg mL–1 cerium with a molar absorptivity of 1.75 × 104 L mol–1 cm–1 and a Sandell's sensitivity of 0.008 μg cm–2. All variables were studied in order to optimize the reaction conditions. The developed method has been successfully applied to the determination of cerium in high purity rare-earth oxides, soil, natural water, plant tissue, human hair, and rock samples.

First order derivative spectrophotometric determination of vanadium(V) and iron(III) individually and simultaneously

A novel, sensitive and highly selective first derivative spectrophotometric method is proposed for the determination of vanadium(V) and iron(III) metal ions separately and simultaneously in a mixture. 2-Hydroxy-1-naphthaldehyde benzoylhydrazone (OHNABH) reacts with vanadium(V) and iron(III) in sodium acetate–acetic acid buffer medium (pH 5.0) forming yellow and yellowish brown colored soluble complexes, respectively. The first derivative curves of these colored solutions show maximum derivative amplitudes at 465 nm (V(V)) and 540 nm (Fe(III)) obeying Beer's law in the range 0.12–2.50 μg ml–1 and 0.14–4.20 μg ml–1, respectively. Large number of foreign ions do not interfere in the present method. A very simple and accurate simultaneous first derivative method is also reported for the determination of V(V) and Fe(III) in mixtures without solving simultaneous equations. The method is applied for the analysis of various natural samples, food and biological materials.

A highly sensitive spectrophotometric determination of platinum(IV) using leuco xylene cyanol FF.

A new, simple, highly sensitive and rapid spectrophotometric method has been described for the determination of platinum(IV). The method is based on the oxidation of leuco xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by platinum(IV) in sulfuric acid medium (pH 1.0-2.5), the formed dye shows an absorption maximum at 620 nm in acetate buffer medium (pH 3.0-4.5). The method obeys Beer's law over a concentration range of 0.3 to 2.6 micro g mL(-1) platinum, having molar absorptivity and Sandell's sensitivity of 5.1x10(4) L mol(-)(1) cm(-1) and 0.0038 micro g cm(-2), respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of platinum in pharmaceutical preparations, soil, natural water, plant material, platinum-containing catalyst, and synthetic alloy samples.

SOLID PHASE EXTRACTION AND SPECTROPHOTOMETRIC DETERMINATION OF COBALT WITH 2-(2-QUINOLINYLAZO)-5-DIMETHYLAMINOBENZOIC ACID AS CHROMOGENIC REAGENT

ABSTRACT A sensitive, selective and rapid method has been developed for the determination µg/L (ppb) level of cobalt(II) based on the rapid reaction of cobalt(II) with 2-(2-quinolinylazo)-5-dimethylaminobenzoic acid (QADMAB) and the solid phase extraction of the colored chelate with C18 cartridge. The QADMAB reacts with Co(II) in the acetate buffer (pH 4.0) and cetyl trimethylammonium bromide (CTMAB) medium, forming a violet chelate of a molar ratio 1 : 2 (cobalt to QADMAB). This chelate can be extracted by C18 cartridge and eluted by ethanol (containing 5% acetic acid). Enrichment factor of 100 was achieved. In this medium, the molar absorptivity of the chelate was 1.40 × 105 L mol−1 cm−1 at 625 nm. Beer's law is obeyed in the range of 0.01–0.4 mg/L. The relative standard deviation for eleven replicate samples of 0.01 mg/L is 2.36%. The detection limit is 0.03 µg/L (in original samples). This method was applied to the determination of cobalt in drinking water with good results.

Production of insoluble dextran using cell-bound dextransucrase of Leuconostoc mesenteroides NRRL B-523

Water-insoluble, cell-free dextran biosynthesis from Leuconostoc mesenteroides NRRL B-523 has been examined. Cell-bound dextransucrase is used to produce cell-free dextran in a sucrose-rich acetate buffer medium. A comparison between the soluble and insoluble dextrans is made for various sucrose concentrations, and 15% sucrose gave the highest amount of cell-free dextran for a given time. L. mesenteroides B-523 produces more insoluble dextran than soluble dextran. The near cell-free synthesis was validated in a batch reactor, by monitoring the cell growth which is a small (10 6–10 7 CFU/mL) and constant value throughout the synthesis.

Oxidation of isoniazid and glutathione with bromamine-T

Bromamine-T oxidizes isoniazid and glutathione stoichiometrically in pit 5 acetate buffer medium with four- and ten-electron change, respectively. Back-titration procedures have been developed for the determination of isoniazid and glutathione. The methods have been successfully employed for the determination of isoniazid in pharmaceutical preparations and also for the estimation of metal complexes of glutathione. A direct titration for the determination of glutathione with a visual end-point is developed involving a one-electron change corresponding to the oxidation of thiol group to disulfide.

Reactivity of alkanols and aryl alcohols towards tetrachloroaurate(III) in sodium acetate–acetic acid buffer medium

AbstractThe oxidative behaviour and relative reactivities of three alkanols and 11 aryl alcohols towards gold(III) in sodium acetate–acetic acid buffer were studied. The reactions are first order with respect to [Au(III)] and in each [R1R2CHOH]. Both H+ and Cl− ions retard the rate of reactions. The reactions obey the following rate expression: AuCl4−, AuCl3(OH2) and AuCl3(OH)− are the reactive species of gold(III) and the reactivity follows the order AuCl3(OH)− &gt; AuCl3(OH2) &gt; AuCl4−. The activation parameters of the reactions were calculated. Alkanols react with gold(III) in the order ethanol &gt; methanol &gt; 2‐propanol. The unsubstituted benzyl alcohol reacts with gold(III) at a faster rate than benzhydrol. The pseudo‐first‐order rate constants in the oxidations of aryl alcohols follow the order NO2 &gt; H &gt; Cl &gt; OMe. The reactions occur via C—H bond cleavage and through the intermediate formation of free radicals. Copyright © 2001 John Wiley &amp; Sons, Ltd.