Indirect spectrophotometric determination of perchlorate using nitron as reagent

An indirect method is outlined for the spectrophotometric determination of small amounts of perchlorate. Perchlorate is quantitatively precipitated as nitron perchlorate in the presence of excess nitron. After separating off the precipitate, the excess reagent is determined in the supernatant liquid as nitron cobaltothiocyanate. The latter compound is extracted in 30% cyclohexanone in carbon tetrachloride and the absorbance of the extract measured at 625 nm. The method is simple, reproducible, and accurate to ±1%. The interferences of other anions were also investigated.     

Indirect spectrophotometric determination of palladium using 1,10-phenanthroline as reagent

Summary The spectrophotometric method for the determination of palladium is based upon the addition of a standard 1,10-phenanthroline solution to precipitate Pd(phen)Cl₂ and the determination of 1,10-phenanthroline concentration of the supernatant solution. The absorbancy readings were made in the absorption maximum at about 271 nm, in the concentration range of 10^–6 to 10^–5M 1,10-phenanthroline in 0.1 M hydrochloric acid and 0.1% hydroxylamine hydrochloride. For the phenanthroline system Beer's law is valid. Ions which either form with phenanthroline very strong complexes or interfere with the spectrophotometric determination of 1,10-phenanthroline must be absent. The method is simple, rapid, accurate and applicable to the macro and micro-determination of palladium in different systems. Standard deviation was found to be 0.085 ppm (in pure Pd solutions).

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Indirekte spektrophotometrische Bestimmung von Palladium mit 1,10-Phenanthrolin

Zusammenfassung Das Verfahren beruht auf der Fällung von Pd(phen)Cl₂ durch Zusatz einer bestimmten Menge Standard-1,10-Phenanthrolinlösung und spektrophotometrischer Bestimmung des Überschusses.Die Messungen werden bei dem Absorptionsmaximum bei etwa 271 nm und einer Konzentration von 10^–6M bis 10^–5M 1,10-Phenanthrolin in 0,1 M HCl und 0,1% Hydroxylaminhydrochlorid enthaltender Lösung durchgeführt. Das 1,10-Phenanthrolinsystem folgt dem Beerschen Gesetz. Ionen, die entweder mit 1,10-Phenanthrolin starke Komplexe bilden oder die spektrophotometrische Bestimmung von 1,10-Phenanthrolin beeinflussen, müssen abwesend sein. Die Methode ist einfach, rasch und genau und kann für Mikro- und Makrobestimmungen in verschiedenen Systemen angewendet werden. Die Standardabweichung beträgt 0,085 ppm (in reinen Pd-Lösungen).

     

Indirect spectrophotometric determination of some reducing agents,using phenolphthalin as reagent

Summary An indirect method for the spectrophotometric determination of microgram amounts of hydroquinone, hydroxylamine and hydrazine is outlined. A known excess of potassium ferricyanide solution is added to the sample solution to oxidise the compound to be determined; the excess of ferricyanide is then determined spectrophotometrically with phenolphthalin. The method is simple, reproducible and accurate to ±2%.

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Zusammenfassung Ein indirekles Verfahren für die spektrophotometrische Bestimmung von Mikromengen Hydrochinon, Hydroxylamin und Hydrazin wurde beschrieben. Eine gemessene überschüssige Menge Kaliumcyanoferrat(III) wird der Probenlösung zugesetzt, um die Verbindung zu oxydieren. Der Überschuß wird dann spektrophotometrisch mit Phenolphthalin gemessen. Das Verfahren ist einfach und auf ±2% genau.

     

Indirect bromometric microdetermination of nitrate and perchlorate,using nitron as reagent

Summary An indirect bromometric method for the determination of nitrate or perchlorate is described. A known excess of standard nitron acetate solution is added to the sample solution to precipitate the anion to be determined; the excess of reagent is then determined in the supernatant liquid by bromatometric titration. The relative standard deviation of the method is 0.7% for nitrate and 0.5% for perchlorate. Sulphate, phosphate and fluoride do not interfere and chloride does not interfere up to a concentration of 0.1 M. Bromide, iodide, chromate, nitrite and chlorate interfere but can be eliminated.

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Zusammenfassung Ein indirektes bromatometrisches Verfahren zur Bestimmung von Nitrat oder Perchlorat wurde beschrieben. Ein gemessener Überschuß einer Nitronacetatlösung bekannter Konzentration wird zur Fällung des Anions der Probe zugesetzt und im Überstand bromatometrisch zurücktitriert. Die rel. Standardabweichung beträgt 0,7% für Nitrat und 0,5% für Perchlorat. Sulfat, Phosphat und Fluorid stören nicht; Chlorid stört nicht bis zu 0,1-m Konzentration. Bromid, Jodid, Chromat, Nitrit und Chlorat stören zwar, können aber eliminiert werden.

     

Indirect spectrophotometric determination of reducing sugars and ascorbic acid using phenolphthalin as reagent

Summary An indirect spectrophotometric method has been developed for the determination of reducing sugars and ascorbic acid. A known excess of ferricyanide is allowed to react with the reductant, and the surplus ferricyanide is determined spectrophotometrically with phenolphthalin. The method is simple and reproducible, with an error of less than 2%.

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Indirekte spektrophotometrische Bestimmung reduzierender Zucker und der Askorbinsäure mit Phenolphthalin

Zusammenfassung Ein gemessener Überschuß von Eisen(III) cyanid wird mit der reduzierenden Probe umgesetzt und der nicht verbrauchte Anteil mit Phenol-phthalin spektrophotometrisch bestimmt. Das Verfahren ist einfach und gut reproduzierbar. Der Fehler ist geringer als 2%.

     

Flow injection spectrophotometric determination of anionic surfactants using methyl orange as chromogenic reagent

A flow injection(FI) spectrophotometric method for the determination of anionic surfactants was developed on the basis of the competition for the cationic surfactant cetyl pyridine (CP+) chloride between the acidic dye methyl orange (MO) and anionic surfactants. In a pH 5.0 medium the cation of cetyl pyridine (CP+) reacts with dissociated methyl orange (MO-) to form an ion-associate complex, causing a blue shift of lambda(max) from 465 nm for MO- to 358 nm for the CP+ x MO- associate. The MO- in the ion-associate complex can be quantitatively substituted by such anionic surfactants as sodium dodecyl benzene sulfonate (DBS) or sodium lauryl sulfate (LS), leading to an increase in the absorbance measured at 465 nm. This increased absorbance value is proportional to the concentration of anionic surfactants. Various chemical and physical parameters for the FI spectrophotometric method were optimized, and interference-free levels were examined. At the optimized conditions, Beer's law was obeyed in the range 1.4 approximately 25 mg/L sodium DBS for an injected sample volume of 180 microL, and a detection limit of 0.22 mg/L for sodium DBS was achieved at a sampling rate of 90 h(-1). Eleven determinations of a 16 mg/L sodium DBS solution gave a RSD of 0.4%. The proposed method has successfully been applied to the determination of anionic surfactant concentration in waste water and in detergents.     

Indirect spectrophotometric determination of silicate

An indirect spectrophotometric method has been developed for trace determination of silicate in aqueous samples. The silicate is converted into silicomolybdic acid and extracted into a mixture of 1-butanol and butyl acetate. The silicomolybdic acid is then decomposed with sodium hydroxide and the molybdenum(VI) reduced to molybdenum(III) with a Jones reductor, followed by reoxidation to molybdenum(VI) with iron(III). The resulting iron(II) is complexed with ferrozine, and the absorbance of the complex measured at 562 run. In this manner, submicroamounts of silicate can be determined.     

Indirect spectrophotometric determination of cyanide

A spectrophotometric method for cyanide based on its inhibition of the colour formation reaction between nickel(II) and 3-(4,5-dimethyl-2-thiazolylazo)-2,6-dihydroxybenzoic acid has been developed, and allows the determination of down to 0.1 g of cyanide. Most of the interferences can be avoided by displacement of the hydrogen cyanide using an arsine generator.     

Kinetic spectrophotometric determination of certain cephalosporins using oxidized quercetin reagent

A simple, precise and accurate kinetic spectrophotometric method for determination of cefoperazone sodium, cefazolin sodium and ceftriaxone sodium in bulk and in pharmaceutical formulations has been developed. The method is based upon a kinetic investigation of the reaction of the drug with oxidized quercetin reagent at room temperature for a fixed time of 30 min. The decrease in absorbance after the addition of the drug was measured at 510 nm. The absorbance concentration plot was rectilinear over the range 80–400 μg mL⁻¹ for all studied drugs. The concentration of the studied drugs was calculated using the corresponding calibration equation for the fixed time method. The determination of the studied drugs by initial rate, variable time and rate-constant methods was feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. The analytical performance of the method, in terms of accuracy and precision, was statistically validated; the results were satisfactory. The method has been successfully applied to the determination of the studied drugs in commercial pharmaceutical formulations. Statistical comparison of the results with a well established reported method showed excellent agreement and proved that there is no significant difference in the accuracy and precision.     

2-Oximinodimedone monoguanylhydrazone as spectrophotometric reagent for determination of iron

The synthesis, properties and analytical possibilities of 2-oximinodimedone monoguanylhydrazone as spectrophotometric reagent have been examined. A new method for the determination of iron has been developed in a concentration range varying from 0·2–5·0 ppm of iron; the molar absorptivity is 1·1×10⁴ litres mol⁻¹ cm⁻¹ at 600 nm and the relative error is ±0·3%. The method has been applied satisfactorily to the determination of iron in different inorganic samples.     

Arsenazo III as a spectrophotometric reagent for determination of lead

Arsenazo III is proposed as a spectrophotometric reagent for the determination of lead. The complex formation begins at pH > 2 and is greatest at pH 4-6. The molar absorptivity of the complex has a mean value of 2.8 x 10(4) 1.mole(-1).cm(-1) at 600 nm and remains nearly constant in the pH range 4-8. The ionic species taking part in the reaction are studied and the equilibrium constants for the different possible reactions are calculated. According to the values obtained, the reaction of PbOH(+) with H(5)L(3-) is predominant. The reaction studied is applied for the determination of micro amounts of lead in technical aluminium.     

The determination of thiols with diphenylpicrylhydrazyl as a spectrophotometric reagent

Diphenylpicrylhydrazyl (DPPH), a stable, intensely purple free radical, is used as a reagent in the quantitative determination of various aromatic and aliphatic thiols by indirect spectrophotometric analysis. Plots of degree of reaction vs. time show that thiophenol and its derivatives react more quickly than aliphatic thiols with DPPH. Calibration plots are linear over the concentration range 0.05-3.00 x 10(-5)M thiol. The average relative error is in the range 1-2% and the absolute standard deviations range up to 0.50 x 10(-6)M.     

Potassium ferrocyanide as a spectrophotometric reagent for the determination of uranium

Potassium ferrocyanide gives a colour reaction with U(VI), which is suitable for its determination. The complex absorbs in the wavelength range of 390–397 nm. The optimum pH range for colour development was 1.5–3.5. The molar absorptivity was found to be 4.65·10³ 1·mol^–1·cm^–1. Most of the anions up to 1000 g did not interfere. The method was made selective by extracting U(VI) first with DOSO from the mixture of interfering cations from 1–2M HNO₃ medium and then determining uranium in the back-extracted solution by developing the colour with ferrocyanide. 20 g/10 ml of U(VI) in the final solution could be satisfactorily determined within an RSD of ±2%.     

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.     

The spectrophotometric and titrimetric determination of gold with ferroin as reagent

A spectrophotometric and a photometric titration method in a two-phase system for the determination of gold with ferroin is reported. Both methods are rapid and reproducible with an accuracy of ±1%. In the spectrophotometric determination Co²⁺, Cu²⁺, Ni²⁺ , Fe³⁺, Zn²⁺, Mn²⁺ and Cr³⁺ do not interfere with the determination of gold and Pt⁴⁺, Pd²⁺, Hg²⁺, Ir⁴⁺ and Os⁴⁺ can be tolerated up to a ratio of 1:1. The titrations can also be carried out in the presence of a number of diverse ions, e.g. Ni²⁺, Cu²⁺, Co²⁺, Fe³⁺, Zn²⁺, Cr³⁺, Mn²⁺, without interference; the platinum metals and Hg²⁺ cause interference but, by the use of the spectrophotometric procedure, this can be reduced.     

Resorcinol as an analytical reagent for the spectrophotometric determination of uranium

A spectrophotometric study of the reaction of uranyl acetate and resorcinol shows that an orange-red coloured resorcinolate of composition 1:2 is formed. This colour reaction can be conveniently used for the spectrophotometric estimation of uranium at PH 4.72.     

A selective spectrophotometric method for determination of rosoxacin antibiotic using sodium nitroprusside as a chromogenic reagent

A selective spectrophotometric method for the determination of rosoxacin (ROS), a 4-quinolone antimicrobial agent, has been developed and validated. The method was based on the reaction of ROS with alkaline sodium nitroprusside (SNP) reagent at room temperature forming a red colored chromogen measured at 455 nm. The conditions affecting the reaction (SNP concentration, pH, color-developing time, temperature, diluting solvent and chromogen stability time) were optimized. Under the optimum conditions, good linear relationship (r=0.9987) was obtained between the absorbance and the concentration of ROS in the range of 20-50 microg ml(-1). The assay limits of detection and quantitation were 2.5 and 8.4 microg ml(-1), respectively. The method was successfully applied to the analysis of bulk drug and laboratory-prepared tablets; the mean percentage recoveries were 100.1+/-0.33 and 101.24+/-1.28%, respectively. The results were compared favourably with those obtained by the reported method; no significant difference in the accuracy and precision as revealed by the accepted values of t- and F-tests, respectively. The robustness and ruggedness of the method was checked and satisfactory results were obtained. The proposed method was found to be highly selective for ROS among the fluoroquinolone antibiotics. The reaction mechanism was proposed and it proceeded in two steps; the formation of nitroferrocyanide by the action of sodium hydroxide alkalinity on SNP and the subsequent formation of the colored nitrosyl-ROS derivative by the attack at position 6 of ROS.     

A novel method for the spectrophotometric determination of cefradine by using sodium nitroprusside as chromogenic reagent

A novel method is developed for the determination of cefradine by using sodium nitroprusside as chromogenic reagent. The experiment indicates that a russety product is formed by the reaction of cefradine with sodium nitroprusside in basic solution, and the maximum absorption wavelength （λmax） of russety product is 505 rim. And the sensitization of tetradecyl benzyl dimethyl ammonium chloride for the reaction of cefradine with sodium nitroprusside is remarkable, The apparent molar absorption coefficient （5505） is 2.81 × 103 L/mol cm. The linear equation isA = 0.0657 ＋ 0.00804C （μg/mL） in the range of 1.50-55.0μg/mL of cefradine with a correlation coefficient r = 0.9992, and the detection limit is 1.38 p,g/mL. This method has been applied to determine cefradine in capsule and tablet samples.