Titrimetric determination of vanadium(IV) with cerium (IV)sulphate at room temperature using ferroin as indicator

A procedure has been developed for the visual titrimetric determination of vanadium(IV) with cerium(IV) sulphate, using ferroin is redox indicator. The method has been extended to the determination of iron(II) and vanadium(IV) in mixtures.     

Indirect determination of uranium by the on-line reduction and fluorimetric detection of cerium(III).

A novel flow injection method has been developed for the indirect determination of uranium by the on-line reduction and subsequent fluorimetric detection of cerium(III). A sample solution containing uranium(VI), prepared as a sulfuric acid solution, was injected into a sulfuric acid carrier solution and passed through a column packed with metal bismuth to reduce uranium(VI) to uranium(IV). The sample solution was merged with a cerium(IV) solution to oxidize uranium(IV) to uranium(VI) and the cerium(III) generated was then monitored fluorimetricaly. The present method is free from interference from zirconium, lanthanides, and thorium, and has been successfully applied to the determination of uranium in monazite coupled with an anion-exchange separation in a sulfuric acid medium to eliminate iron(III). The sample throughput was 25 per hour and the lowest detectable concentration was 0.0042 mg l(-1).     

Titrimetric and spectrophotometric methods for the determination of cerium(IV) in aqueous solution

A titrimetric and spectrophotometric methods for cerium(IV) determination have worked out. The first method relies upon the treatment of cerium(IV) solution with an excessive amount of iodide; the liberated iodine is extracted into chloroform, then reduced to iodide. The latter is iodometrically determined after 6- or 36-fold amplification. The spectropho-tometric finish is based upon the reaction of the titled ion with iron(II), in the presence of hexacyanoferrate(II), to form an intense prussian blue color suitable for the trace determination of cerium(IV) ion.     

Amperometric ascorbimetric determination of cerium(IV) and Iron(III) with two polarized electrodes

Summary Amperometric ascorbimetric determinations of cerium(IV) and ferric iron have been carried out at 50°C with two polarized electrodes at 200 and 100 mV respectively. The results obtained are fairly accurate and precise within ±1.0 per cent. A simple method for successive determination of cerium and iron has been developed; and conditions for such estimations have been established. At an acidity of 2.5 M with respect to sulphuric acid, it is possible to ward off the reduction of ferric iron and thereby cerium(IV) is successfully titrated with ascorbic acid in this medium. After completion of the reaction and then lowering the acid concentration to p_H 1.5 with aid of ammonium hydroxide, Fe^III is titrated with standard ascorbic acid yielding good results.     

Fluorimetric determination of cerium with paracetamol

A simple, sensitive and selective method for determination of cerium(IV), based on the oxidative reaction between cerium(IV) and paracetamol, has been developed. The fluorescent species is an oxidation product of paracetamol and has excitation and emission maxima at 265 and 360 nm, respectively. The fluorescent intensity of the system is linear over the range 2.0 x 10(-7)-8.0 x 10(-6)M Ce(IV). The method has been applied in the determination of Ce(IV) in synthetic mixtures and ores with good accuracy being achieved.     

Spectrophotometric determination of cerium(IV) using a phenothiazine derivative.

A simple, rapid and sensitive spectrophotometric method has been proposed for the determination of cerium(IV) using a phenothiazine derivative, propionyl promazine phosphate (PPP). This method is based on the formation of a red-colored radical cation upon a reaction of PPP with cerium(IV) in a phosphoric acid medium having maximum absorbance at 513 nm. Beer's law is valid over the concentration range of 1-11 microg/ml with a Sandell's sensitivity value of 16.14 ng/cm2. The proposed method has been successfully applied to the analysis of magnesium-base cerium alloys and synthetic mixtures corresponding to various cerium alloys. Other phenothiazine derivatives viz. butaperazine dimaleate and propericiazine were also used for the determination of cerium(IV).     

Titrimetric determination of U(iv) alone and in mixtures with V(IV), Mn(II), Ce(III) and Fe(II)

Summary A rapid and accurate method is described for the potentiometric determination of uranium(IV) with permanganate at room temperature using trace amounts of ortho-phosphoric acid as a catalyst. The procedure has been extended for the differential potentiometric determination of mixtures with vanadium, manganese or cerium. The methods are easy, non-time consuming and free from interference by a large number of foreign ions. Conditions are also developed for the differential photometric determination of uranium and iron in mixtures.Based on these procedures, a differential titrimetric procedure has been developed for determination of iron(III), vanadium(V), chromium(VI) and manganese(VII) [or cerium(IV)] in a single solution at room temperature. This procedure has also been tested on Bureau of Standard samples.

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Titrimetrische Bestimmung von U(IV) allein und in Mischungen mit V(IV), Mn(II), Ce(III) und Fe(II)Anwendung auf die Analyse von Stählen und Legierungen

Zusammenfassung Eine schnelle und genaue Methode wird beschrieben zur potentiometrischen Bestimmung von Uran(IV) mit Permanganat bei Raumtemperatur unter Verwendung von Spuren Orthophosphorsäure als Katalysator. Das Verfahren wurde auf die differentialpotentiometrische Bestimmung im Gemisch mit V, Mn und Ce ausgedehnt. Die rasch und einfach ausführbare Methode wird durch zahlreiche Fremdionen nicht gestört. Eine differentialphotometrische Bestimmung von U(IV) und Fe(II) im Gemisch wird ebenfalls angegeben, außerdem eine differentialtitrimetrische Bestimmung von Fe(III), V(V), Cr(VI), Mn(VII) [oder Ce(IV)] in einer Lösung. Anwendungsbeispiele für Stähle und Legierungen werden beschrieben.

     

Separation of matrix absorption and enhancement effects in the determination of sulfur in sea water by X-ray fluorescence

The analytical utility of chloranil-loaded polyurethane foam in a syringe column was investigated. A rapid method for the determination of micro and semimicro amounts of cerium(IV), vanadium(V) and iron(III) by means of this redox “pulsed” column has been developed. The effects of number of pulses, temperature and concentration of metal ion in solution on the reduction efficiency of the proposed pulsed column were critically studied. Analyses for different concentrations of Ce(IV), V(V) and Fe(III) were successfully carried out with an average relative error of ±2.2%.     

Spectrophotometric determination of trace amounts of iron(III) with norfloxacin as complexing reagent

The complexation of iron(III) with norfloxacin in acidic solution at 25 degrees C, at an ionic strength of about 0.3 M and a pH of 3.0 has been studied. The water-soluble complex formed, which exhibits an absorption maximum at 377 nm, was used for the spectrophotometric determination of trace amounts of iron(III). The molar absorptivity was 9.05 x 10(3) I mol-1 cm-1 and the Sandell sensitivity 6.2 ng cm-2 of iron(III) per 0.001 A. The formation constant (Kf) was determined spectrophotometrically and was found to be 4.0 x 10(8) at 25 degrees C. The calibration graph was rectilinear over the range 0.25-12.0 p.p.m. of iron(III) and the regression line equation was A = 0.163c - 0.00042 with a correlation coefficient of 0.9998 (n = 9). Common cations, except cerium (IV), did not interfere with the determination. The results obtained for the determination of iron(III) using the described procedure and the thiocyanate method were compared statistically by means of the Student t-test and no significant difference was found.     

Kinetic and analytical studies on the oxidation of methanol and ethanol by ammonium hexanitratocerate(IV)

A detailed study of the kinetics of the oxidation of methanol with ammonium hexanitratocerate(IV) has shown interesting features which differ from the kinetics of the oxidation with cerium (IV) perchlorate. The different features are discussed in terms of the species of cerium(IV) occurring in solutions of cerium(IV) in nitric acid and perchloric acid. Improved procedures have been developed for the determination of methanol and ethanol with cerium(IV) nitrate.     

Titration of cerium (IV) sulphate with sodium oxalate at the room temperature using ferroin as internal indicator

Summary A method has been developed for the titration of cerium(IV) sulphate with sodium oxalate at the room temperature, using ferroin as internal indicator. A new principle has been utilised for facilitating the indicator action at the equivalence point. This involves the use of a photochemical reaction between the oxalate and iron(III) which is deliberately added to the mixture containing cerium(IV) sulphate and ferriin. When the mixture is titrated with the sodium oxalate solution under exposure to the light from a Philips Repro lamp, the addition of a very slight excess of sodium oxalate solution, after all the cerium(IV) sulphate has reacted, produces a vivid red colour. The slight excess of sodium oxalate added reacts with the iron(III) salt photochemically producing a trace of iron(II) salt which reduces the ferriin to the red ferroin. In titrations with 0.1 and 0.05 N solutions of sodium oxalate, the error is negligible. In titrations with sodium oxalate solution of lower strengths, the error amounts to 0.02 ml of 0.01 N oxalate which has to be subtracted from the titre.     

Integrated scheme for micro-determination of iron oxidation states in silicates and refractory minerals

A mirco-analytical scheme incorporating four methods is described for the determination of iron(II) and iron(III) in both hydrofluoric acid-soluble and refractory minerals. The acid-soluble minerals are analyzed for FeO by direct constant-current potentiometric titration with potassium dichromate, and a separate solution is titrated similarly after Zn/Hg reduction to give total iron. The micro-determination of FeO in chromite and other refractory minerals involves dissolution in a cerium(IV)/phosphoric acid mixture and constant-current potentiometric and indirect titration of excess of cerium(IV) (phosphatocerate) with iron(II). Lithium tetraborate micro-fusion is required for measurement of total iron by atomic absorption spectrometry or spectrophotmetry. The average relative standard deviation ranged between 0.73 and 1.08%.     

Ammonium hexanitratocerate(IV) as an oxidizing agent-VI Determination of chronuum(III) through oxidation to chromium(VI) at room temperature

A new method has been developed for the determination of chromium(III), depending on its oxidation to chromium(VI) at room temperature by treatment with 50-100% excess of ammonium hexanitratocerate(IV) in 1.0M nitric acid medium. The reaction is complete within 15 min. The unreacted cerium(IV) is titrated potentiometrically with sodium oxalate.     

丽春红S褪色光度法测定微量铈

依据在酸性条件下,铈Ce(IV)的强氧化性使丽春红S褪色的原理,建立了一种褪色光度法测定微量铈的新方法。实验结果表明:丽春红S溶液的最大吸收波长为510 nm,铈量在0～5.0 mg/L范围内遵循比尔定律,线性回归方程为:y=0.0048x-0.0068,相关系数为r=0.9993,表观摩尔吸光系数为ε510=2.18×104L.mol-1.cm-1。新方法用于稀土氧化物中微量铈的测定,样品分析结果的相对标准偏差为0.99%(n=5),加标回收率为96.9%～99.0%。     

Sequential injection technique for automated titration: spectrophotometric assay of vitamin C in pharmaceutical products using cerium(IV) in sulfuric acid

For the first time sequential injection analysis (SIA) technique has been employed for titrimetry. A new SI titrimetric spectrophotometric method for the assay of vitamin C in drug formulations was explored. The method is based on the oxidation reaction of vitamin C with cerium(IV) in sulfuric acid media using a spectrophotometer as a detector with the wavelength monitored at 410 nm. A 2(3) factorial design chemometric approach was employed to study the interaction effect of the chemical and system variables, mainly cerium(IV), sulfuric acid concentrations and the flow rate. The results of the chemometric optimization revealed that the optimum operating conditions for the SI titrimetric analysis of vitamin C were 7.0 x 10(-3) M cerium(IV), 0.455 M sulfuric acid and 28.9 microL s-1 flow rate. A linear calibration plot for the determination of vitamin C was obtained in the concentration range between 30 to 200 ppm. The method was applied to the determination of vitamin C in pharmaceutical preparations and no excipient was found to pose any interference, thus rendering the method suitable for the determination of the drug in pharmaceutical preparations. The SIA method is found to be accurate when the results were statistically compared with the results obtained by the BP standard method. The SIA method is superior when compared to the conventional titration method, the BP standard method and previous methods with respect to precision and automation in solution handling.     

Catalytic spectrophotometric determination of trace amount of cerium(IV)

Based on a property that in dilute hydrochloric acid hydrogen peroxide oxidizes Ponceau S to fade and cerium(IV) has a catalytic effect on the reaction, a new spectrophotometric method was developed for the determination of trace cerium(IV). At 450 nm, the cerium(IV) concentration presents a good linear relationship over the range of 0.08?4 μg/mL with the fading degree ΔA. Its linear regression equation is ΔA = 0.0475c (μg/mL) + 0.0007, with a correlation coefficient of 0.9991. The detection limit of method is 0.05 μg/mL. The method has been successfully applied to the determination of cerium in water and molecular sieve samples with good results. The relative standard deviations of eleven determinations were 0.97?1.11 and 0.19?1.01%, respectively. The recoveries of standard additions were 99.4?99.9 and 99.2?101.0%, respectively. The reliability of this method was certified by parallel determination against the dibromo-p-chlorochlorophosphonazo spectrophotometry.     

Catalytic effect of copper on the hexacyanoferrate(III)-cyanide redox reaction-II catalytic determination of copper

A catalytic method for the determination of copper, based on the catalysis of the hexacyano-ferrate(III)-cyanide redox reaction, is proposed. Experimental conditions to achieve the lowest detection limit are selected from the kinetics of both the catalysed and the uncatalysed reactions. The experimental measurements can be made at room temperature without close control. The rate-constant method is the most sensitive and precise, whereas the fixed-concentration and fixed-time methods appear to be the most rapid for routine analysis. A detection limit of 1.3 ng/ml and a coefficient of variation of about 3% for the determination of 63 ng/ml can be achieved. The catalytic effect of copper seems to be highly specific. Lead(II), bismuth (III), antimony (III), iron (II), iron(III), chromium(III), lanthanum(III), cerium(III), titanium(IV), zirconium(IV) and uranium(VI) interfere by precipitation. Species such as tin(II), cobalt(II), manganese(II), sulphite and thiosulphite cause serious interference because they react with hexacyanoferrate(III). Chromate interferes by its colour. Suitable methods to avoid the interferences from antimony(III), iron(III), chromium(III), titanium(IV), zirconium(IV), uranium(VI) and chromate are proposed.     

Highly sensitive spectrophotometric determination of olanzapine using cerium(IV) and iron(II) complexes of 1,10-phenanthroline and 2,2′-bipyridyl

Two highly sensitive spectrophotometric methods have been developed for the determination of olanzapine (OLP) in pharmaceuticals using cerium(IV) and iron(II) complexes of 1,10-phenanthroline and 2,2′-bipyridyl as reagents. The methods are based on the oxidation of OLP in acidic medium by a known excess of cerium(IV) followed by the determination of the unreacted oxidant by reacting with either ferroin and measuring the absorbance at 510 nm (method A) or iron(II)-2,2′-bipyridyl complex and measuring the absorbance at 525 nm (method B). The amount of cerium(IV) reacted corresponds to the amount of OLP. In both the methods, the absorbance is found to increase linearly with OLP concentration as shown by the correlation coefficient (r) of 0.9980 and 0.9958 for method A and method B, respectively. The calibration graphs are linear over the concentration range of 0.2–2.0 μg/mL in both the methods. The calculated molar absorptivity values are 1.00 × 10⁶ and 7.03 × 10⁵ L/mol cm, for method A and method B. The LOD and LOQ values for method A are calculated to be 0.04 and 0.13 μg/mL and the values are 0.07 and 0.22 μg/mL for method B, respectively. The methods were validated as per the current ICH guidelines. Both the methods gave similar results in terms of accuracy and precision. The RSD was less than 3% and the accuracy, obtained from recovery experiments, was 98.76–101.4%. The methods developed were applied to the determination of OLP in tablets and results agreed well with the label claim.     

Titration of vanadium(IV) with cerium(IV) sulphate, with ferroin as indicator, in aqueous acetone as facile reaction medium An analytical and mechanistic study

A new procedure for the titration of vanadium(IV) with cerium(IV) sulphate, with ferroin as indicator, in aqueous acetone medium is reported. A differential determination of iron(II) and vanadium(IV) is also possible. A probable mechanism for the fast ferriin-vanadium(IV) reaction in acetone medium is given.     

Cerimetrie en milieu nitrique. application au dosage du fer,de l'uranium et du plutonium

A method is described for titrimetric determination of iron, uranium or plutonium in nitric acid media. The element is reduced with titanium(III) solution in presence of sulfamic acid, and titrated with cerium(IV) solution. Precautions normally taken for nitric acid media are unnecessary. The method is rapid and precise and is readily applicable to determinations of plutonium or irradiated uranium.