Chlorophosphonazo-p-Cl,a new reagent for the spectrophotometric determination of scandium

Summary Chlorophosphonazo-p-Cl, A New Reagent for the Spectrophotometric Determination of Scandium The synthesis of chlorophosphonazo-p-Cl (CPApC) and a highly sensitive method with CPApC as a new reagent for the spectrophotometric determination of scandium are described. Scandium reacts with CPApC in nitric acid medium at pH 2 to form a 11-type complex which has a maximum absorption at 762 nm. Under the experimental conditions employed, the apparent molar absorptivity is 1.54×10⁵ l·mol^–1·cm^–1 and the relative standard deviation for 2.0g of scandium is 0.92%. The determination range is 0–6g of scandium in 25 ml of solution by using standard addition-deduction method. Scandium can be determined in the presence of reasonable amounts of rare earths.This work was supported by the Science Fund of the Chinese Academy of Sciences.     

The spectrophotometric determination of rhenium

Some 50 analytical reagents were briefly checked for use in the spectrophotometric determination of rhenium. Seven reagents were checked in detail and interferences were examined. The most promising reagents appeared to be I-phenyl-2-thiourea and I,5-diphcnylcarbohydrazide.     

Guaiacol as a new reagent for the spectrophotometric determination of uranium

Guiacol, i.e. o-hydroxyanisole, gives a distinct color reaction with U(VI) suitable for spectrophotometric determination of the metal. The complex formed in the reaction has an absorption maximum at 352 nm. Optimum pH for the color development ranges from 6.5 to 8.5. The molar absorptivity and Sandell's sensitivity of the method were found to be 3.75×10³ l·mol^–1·cm^–1 and 0.063 g·cm^–2, respectively. Many anions and cations do not interfere up to 100 ppm. The method has been made very specific by selective extraction of U(VI) with TBP from a mixture of different cations and anions in the presence of 60% NH₄NO₃ as salting out agent followed by developing the color in the non-aqueous phase by adding quaiacol in methanol at pH 6.5 to 8.5 An amount as low as 30 g of uranium (VI) per 10 ml of the solution could be satisfactorily determined with an RSD of ±2.0%. The method was applied to rock samples after U(VI) had been extracted from a sample solution into 25% TBP in hexane. Results obtained by the new method compare very well with those of conventional fluorimetric and radiometric assays. The features of the method include excellent precision, rapidity, good selectivity, and ease of performance.     

Neotetrazolium chloride: a new reagent for spectrophotometric determination of manganese

The interaction of Mn(VII) and the Neotetrazolium chloride has been examined. The ion-associate formed is extracted into 1,2di-chloroethane. The optimum conditions have been established. The molar absorptivity of the complex is (9.1+/-0.08)x10(5) l mol(-1) cm(-1). The sensitivity of the method is 6.04x1010(-5) mug cm(-2). It is possible to extract and determine manganese in the presence of large number of cations and anions. The characteristic values for the extraction and the aqueous phase equilibria were determined: extraction constant K(ex)=3.21x10(9), distribution constant K(D)=33 and association constant beta=9.72x10(7). The method is applicable to analysis of soils and steels.     

Oxidized haematoxylin,a new reagent for the spectrophotometric determination of penicillins and cephalosporins

Haematoxylin—Chloramine-T in phosphate buffer (pH 7.0) is proposed as a new reagent for spectrophotometric determination of penicillins and cephalosporins in pure samples and pharmaceutical preparations. The method is based on acid hydrolysis of penicillins and cephalosporins with 5M HCl and subsequent treatment with oxidized haematoxylin. The resulting colour exhibits maximum absorption at 555 nm.     

A new reagent system for the highly sensitive spectrophotometric determination of selenium

Highly sensitive and simple spectrophotometric determination of selenium is described for the determination of selenium(IV) using a new reagent leuco malachite green. The method is based on the reaction of selenium(IV) with potassium iodide in an acidic condition to liberate iodine, the liberated iodine oxidizes leuco malachite green to malachite green dye. The green coloration was developed in an acetate buffer (pH 4.2–4.9) on heating in a water bath (∼ 40 °C). The formed dye exhibits an absorption maximum at 615 nm. The method obeys Beer’s law over a concentration range of 0.04–0.4 μg mL⁻¹ selenium. The molar absorptivity and Sandell’s sensitivity of the color system were found to be 1.67 × 10⁵ L mol⁻¹ cm-¹ and 0.5 ng cm⁻², respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The proposed procedure has been successfully applied to the determination of selenium in real samples of water, soil, plant material, human hair, and cosmetic samples. The results were compared to those obtained with the reference method. Statistical analysis of the results confirms the precision and accuracy of the proposed method. In addition, the developed method is cost-effective and involves easily accessible instrumentation technique which can be used by ordinary research laboratories.     

Prochlorperazine bismethanesulfonate as a new reagent for the spectrophotometric determination of palladium

A simple, rapid, and selective method for the determination of palladium is described. The orange-red palladium(II)-prochlorperazine bismethanesulfonate complex in the presence of hydrochloric acid-sodium acetate buffer exhibits maximum absorbance at 480 nm with a molar absorptivity of 4.32 × 10³ liters mol^?1 cm^?1. The sensitivity of the reaction is 24.62 ng cm^?2. The system obeys Beer's law over the concentration range 0.4–20 ppm of palladium with an optimum concentration range of 1–19 ppm. The apparent stability constant of the complex is found to be log K = 5.3 ± 0.1 at 27 °C. The effects of pH, time, temperature, order of addition of reactants, reagent concentration, and interferences from various ions are reported. The proposed method offers the opportunity to carry out the determination at room temperature without the need for an extraction step. The method is also found to be suitable for the determination of palladium in jewelry alloy.     

Tungstophosphoric acid as a new reagent for the spectrophotometric determination of phenothiazines

A simple and rapid spectrophotometric method for the determination of phenothiazines based on the formation of a colored compound between tungstophosphoric acid and phenothiazines is described. The proposed method is successfully employed for the determination of phenothiazine drugs in various pharmaceutical products.     

o-Dianisidine: a new reagent for selective spectrophotometric, flow injection determination of chlorine.

A flow injection analysis (FIA) procedure for the determination of free chlorine in industrial formulations and water samples is proposed. The manifold is provided with a gas-diffusion unit which permits the removal of interfering species and also the preconcentration of chlorine. The determination of chlorine is performed on the basis of the oxidation by o-dianisidine as a chromogenic reagent to a coloured product which can be monitored at 445 nm. The method (for a preconcentration step of 60 s) is linear over the range 0.04-1.00 mg l(-1) of chlorine, the limit of detection is 0.04 mg l(-1), the reproducibility of the procedure (as RSD of the slope) is 3.7% for a series of four independent calibrations, the precision (as RSD of a series of 30 continuous FIA peaks of 0.56 mg l(-1) of chlorine) is 1.4% and the sample throughput is 40 h(-1). A detailed comparative study of the analytical characteristics of a single mono-channel reverse FIA assembly and the same system but provided with a Fluoropore membrane filter of 0.5 microm pore size was performed to check the advantages of the new approach in terms of sensitivity, selectivity and limit of detection.     

A new reagent for the colorimetric and spectrophotometric determination of phosphorus,arsenic and germanium

A new reagent for the colorimetric and spectrophotometric determination of phosphorus, arsenic and gurmanium is described. It contains Mo(Vl) amd Mo(V) in the ratio of 3 : 2 in an acid medium, 10N with respect to H₂SO₄ and 3N with respect to HCl.The absorption spectra, the influence of temperature, time, quantity of reagent and selectivity of the method have been studied. Beer's law is applicable up to 160 μg for P₂O₅, 220 μg for GeO₂ and 230 μg for arsenic, in 50 ml.     

New reagent for spectrophotometric determination of salicylic acid

In 6M hydrochloric acid solution, salicylic acid reacts with pentachloronitrosyliridate [Ir(NO)Cl(5)](-) to form a new 1:1 complex giving two absorption maxima at 369 and 446 nm with molar absorptivities both of 1.1 x 10(4) l.mole(-1) cm(-). The reaction is second order with apparent energy, E(a), of 16.8 kJ/mole. At constant temperature, the apparent rate constant k increases to a maximum when the concentration of hydrogen ion is decreased to 4-5M and the concentration of chloride ion is kept at approximately 6M. The mechanism of the reaction is also discussed. In alkaline solution, the absorption maxima shift to 381 and 506 nm with molar absorptivities of 6.0 x 10(3) and 2.4 x 10(4) l.mole(-1) cm(-1), respectively. Salicylic acid can be determined spectrophotometrically with high sensitivity and precision. Benzoic and boric acids do not interfere.     

Di-2-Pyridylketoxime,a new reagent for the spectrophotometric determination of iron(II)

Di-2-pyridylketoxime is proposed for the spectrophotometric determination of iron(II). The complex is stable and exhibits an absorption maximum at 534 nm in an alkaline citrate medium. Beer's law is obeyed and the molar absorptivity is 1.5·10³. Large amounts of copper and nickel can be tolerated. The method is simple, convenient and reproducible.     

A new polymeric chromogenic reagent for dual-wavelength spectrophotometric determination of iron(III)

By condensing chitosan with 7-(4-formyl-phenylazo)-8-quinolinol-5-sulfonic acid (FPAQS), a new polymeric chromogenic reagent C-FPAQS has been synthesized and its properties investigated. In acidic media (pH 2.7), C-FPAQS reacts with iron(III) to yield an orange complex with a molar absorptivity of 2.8 × 10⁴ lmol^–1 cm^–1 at 420 nm, and in the meantime a negative peak at 524 nm. The apparent molar absorptivity (420–524 nm) obtained by dual-wavelength measurements is 7.9 × 10⁴lmol^–1cm^–1 which is about two times higher than that by single-wavelength measurements at 420 nm Beer's law is obeyed in the range of 0–0.8 g ml^–1 for iron(III). The developed method has been satisfactorily used to determine iron at the 0.03 to 3% (ww) level in a nylon-6 and in a soil sample. Compared to the corresponding low-molecular weight FPAQS and other chromogenic reagents, C-FPAQS has not only good sensitivity but also largely increased acid solubility and improved selectivity for iron, which may be explained by the incorporation of FPAQS into an acid-soluble polymer.     

Benzeneacetaldehyde-4-hydroxy-alpha-oxo-aldoxime as a new analytical reagent for the spectrophotometric determination of cobalt

Benzeneacetaldehyde-4-hydroxy-α-oxo-aldoxime is proposed as a new sensitive and selective reagent for the spectrophotometric determination of cobalt. The reagent reacts with cobalt in the pH range 8.6–9.4 to form a yellow colored 1:3 chelate which is very well extracted in chloroform. Beer's law is obeyed in the concentration range 0.05–1.3 μg ml⁻¹ cobalt. The molar absorptivity of the extracted species is 2.746×10⁴ l mol⁻¹ cm⁻¹ at 390 nm. The proposed method is highly sensitive, selective, simple, rapid, accurate and has been satisfactorily applied for the determination of cobalt in synthetic mixtures, pharmaceutical samples, biological samples and alloys.     

2,2'-Diaminodiphenyldisulphide-a new sensitive spectrophotometric reagent for platinum

2,2'-Diaminodiphenyldisulphide is a highly sensitive platinum chromogen. Platinum(IV) forms a complex with it in 50% aqueous ethanol at pH 5.0-6.0, having maximum absorption at 725 nm. The molar absorptivity of the complex is 5.48 x 10(4)1.mole(-1).cm(-1) at 725nm and the sensitivity is 0.0035 mug/cm(2). The colour system obeys Beer's law from 0.25 to 5 ppm with optimum concentration range 0.75-4 ppm of platinum. The relative error is 2.7%. The metal to reagent ratio is 1:2, and the stepwise formation constants K(1) and K(2) are 5.6 x 10(4) and 1.96 x 10(4) respectively.     

A new reagent for the spectrophotometric determination of magnesium (II): Khimduchlorophosphonazo-I

Summary The colour reaction of magnesium(II) with Khimduchlorophosphonazo-I (KCPA-I) has been studied spectrophotometrically with a view to develop a procedure for the determination of exchangeable magnesium in acidic soils.The optimum acidities are pH 8.78–9.90. The absorption maximum and molar absorptivity of the coloured complex are 580 nm and 1.85 · 10⁴ l · mol^–1 · cm^–1, respectively. The colour intensity is stable for 4 h and is found to obey Beer's law within the concentration range of 0–20 g per 25 ml. The method is simple and reliable (standard deviation 0.8–1.2%). It has been applied to the determination of exchangeable magnesium.

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Neues Reagens für die spektralphotometrische Bestimmung von Magnesium (II): Khimduchlorophosphonazo-I

Zusammenfassung Die Farbreaktion von Magnesium mit Khimduchlorophosphonazo-I wurde im Hinblick auf die Entwicklung eines entsprechenden Analysenverfahrens untersucht. Der optimale pH-Wert liegt im Bereich von 8,78–9,90. Das Absorptionsmaximum liegt bei 580 nm, der molare Extinktionskoeffizient beträgt 1,85 · 10⁴l · mol^–1 · cm^–1. Die Färbung bleibt 4 h lang stabil und befolgt das Beersche Gesetz von 0 bis 20 g/25 ml. Das Verfahren ist einfach und zuverlässig (Standardabweichung 0,8–1,2%) und wurde zur Bestimmung von austauschbarem Magnesium in sauren Böden angewendet.

     

2,2′-Diquinolyl ketoxime: A new reagent for the spectrophotometric determination of cobalt

Summary The synthesis of 2,2-diquinolyl ketoxime and its application to the spectrophotometric determination of cobalt is described. The effects due to p_H, time, solvents, reagent concentration and diverse ions are reported. Beer's law is obeyed and the molar extinction coefficient is 5.3 · 10⁴ at 365 nm.

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Zusammenfassung Die Synthese von 2,2-Dichinolylketoxim und dessen Verwendung zur spektrophotometrischen Bestimmung von Kobalt wurde beschrieben. Der Einfluß von pH, Zeit, Lösungsmitteln, Reagenskonzentration und verschiedenen Fremdionen wurden untersucht. Das Beersche Gesetz ist gültig; der molare Extinktionskoeffizient beträgt bei 365 nm 5,3 · 10⁴.

     

Ascorbic acid as a new reductant in the thiocyanate method for the spectrophotometric determination of rhenium

Summary A spectrophotometric determination of rhenium is based on its reduction with ascorbic acid in the presence of thiocyanate. The orange-yellow complex is extracted into isoamyl alcohol and the absorbance measured at 430 nm. Various foreign ions do not interfere. Molar absorptivity and Sandell's sensitivity are 31162.79 l/mol/cm and 0.0059 g/cm², respectively.     

A simple and selective kinetic spectrophotometric method for the determination of kanamycin using acetylacetone-formaldehyde reagent in N,N′-dimethylformamide medium

A simple, sensitive, and selective kinetic spectrophotometric method for the determination of kanamycin in pure form and pharmaceutical formulations is described. The method is based on the measurement of the intensity of the yellow chromogen formed by the reaction between kanamycin and acetylacetone-formaldehyde reagent in a N,N′-dimethyl formamide medium. The variable-time method was used to evaluate the rate of reaction of the colored chromogen formed at 410 nm. The reaction conditions were optimized and the calibration graph was found to be linear in the range 60–160 μg/mL. The results obtained by the developed and reference methods are in good agreement. Various statistical parameters were evaluated to establish the precision, accuracy, repeatability, and reproducibility of the proposed method. The text was submitted by the authors in English.