Spectrophotometric determination of Fe(III) with tiron in the presence of cationic surfactant and its application for the determination of iron in Al-alloys and Cu-based alloys

A sensitive Spectrophotometric method for the determination of iron with tiron and a cationic surfactant, cetylpyridinium chloride, at pH 5.6 is reported. The complex is extracted into a chloroform-propan-2-ol (41) mixture and shows maximum absorbance at 520 nm. Beer's law is obeyed in the range 1–14 g/ml with an average molar absorptivity of 15800 l mol^–1 cm^–1. The molar ratio as determined by Job's method for Fe:tiron:CPC is 143. Interferences by various ions are examined. Zr, Ti and Mo interfere heavily. The method is applied for the determination of iron in Al-based and Cu-based alloys, using appropriate masking agents.     

Spectrophotometric determination of iron after separation of its 9,10-phenanthrenequinone monoximate on microcrystalline naphthalene

A sensitive and selective spectrophotometric method has been developed for the determination of iron as Fe(II) or Fe(III) using 9,10-phenanthrenequinone monoxime (PQM) as the complexing agent. Fe(II) and Fe(III) react with PQM to form coloured water insoluble complexes which can be adsorbed on microcrystalline naphthalene in the pH ranges 3.7–6.2 and 2.0–8.4, respectively. The solid mass consisting of the metal complex and naphthalene is dissolved in DMF and the metal determined spectrophotometrically by measuring the absorbances Fe(II) at 745 nm and Fe(III) at 425 nm. Beer's law is obeyed over the concentration range 0.5–20.0 g of iron(II) and 20–170.0 g of Fe(III) in 10 ml of DMF solution. The molar absorptivities are 1.333 × 10⁴ 1 · mole^–1 · cm^–1 for Fe(II) and 2.428 × 10³1· mole^–1 · cm^–1 for Fe(III). The precision of determination is better than 1%. The interference of various ions has been studied and the method has been employed for the determination of iron in various standard reference alloys, bears, wines, ferrous gluconate, human hair and environmental samples.     

Direct spectrophotometric determination of iron in non-ferrous alloys

Disodium 3-(2-pyridyl)-1,2,4-triazine-5,6-di(4'-phenylsulphonate) is used for determination of iron in metal analysis. High selectivity is achieved by using a ligand buffer and substoichiometric masking. Interference from 0.9 mg of Cu(II) can be completely eliminated by combined reduction and masking with ascorbic acid and thiosemicarbazide. Beer's law is obeyed over the range 0.4-1.6 mug/ml iron in the final solution, with a standard deviation of 0.02 mug/ml. The method has been successfully applied to determination of iron (without preseparation) in a number of non-ferrous metals and alloys, with a coefficient of variation of 1.2-5.0%.     

Spectrophotometric determination of magnesium in aluminium alloys

The determination of magnesium in aluminium alloys by a differential spectrophotometric method is describcd. Magnesium is separated and the absorbance of its coloured complex with Eriochrome Black T measured.     

Spectrophotometric extractive determination of Ti in mineral samples and aluminium alloys as a mixed-ligand Ti(IV)-salicylhydroxamic acid-thiocyanate complex

A sensitive method for the determination of titanium, based on the formation of a mixed-ligand Ti (IV)-salicylhydroxamic acid-thiocyanate complex and extraction of this into a liquid ion-exchanger phase has been developed. The extract has maximum absorbance at 400–460 nm and the apparent molar absorptivity is 1.8 × 10⁴l · mole^–1 · cm^–1 at 420 nm. The system obeys Beer's law at 420 nm in the range 0.16–3.20 mg/1 Ti, the detection limit being 0.1 mg/1. The method is found suitable for determination of titanium in aluminium alloys and silicate rocks.     

Simultaneous determination of cobalt,nickel and iron by multi-wavelength spectrophotometry

A method for the simultaneous spectrophotometric determination of cobalt, nickel and iron based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is proposed. The absorption curves of these complexes overlap severely in the scanning range 390–510 nm. The analyte concentrations are calculated by a least squares fit of the pure spectra to the mixture spectra, which therefore makes the simultaneous determination of these metallic ions possible without tedious pretreatment. The detection limits afforded by the proposed method range from 0.05 g/ml for Fe and Ni to 0.1 g/ml for Co. Root-mean-squared errors of prediction of 0.085 g/ml for Co, 0.048 g/ml for Ni and 0.1172 g/ml for Fe were obtained using the wavelength range 400–510 nm and 0.147 g/ml for Co, 0.107 g/ml for Ni and 0.127 g/ml for Fe using the wavelength range 420–434 nm. The effect of interferences is studied and the proposed method is applied to analysis for the above elements in synthetic samples and real samples, such as biological materials and alloys.     

Complexation equilibria between copper(II) and thiosalicylic acid. Spectrophotometric determination of copper in non-ferrous alloys

Summary The complexation equilibria of Cu(II) with thiosalicylic acid (TSA) have been studied spectrophotometrically in aqueous ethanol (17.08 mol% ethanol) atI=0.1M (NaClO₄) and 25±0.1°C. Analysis of the absorbancevs. pH graphs afforded the equilibria in solution and the stability constants of the complexes formed. A simple, rapid, and sensitive method for the spectrophotometric determination of trace amounts of copper is proposed. The effect of interference of a large number of foreign ions was studied. The method has been applied successfully to the analysis of some synthetic mixtures and non-ferrous alloys containing copper.

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Komplexierungsgleichgewichte zwischen Kupfer(II) und Thiosalicylsäure. Spektrophotometrische Bestimmung von Kupfer in eisenfreien Legierungen

Zusammenfassung Die Komplexierungsgleichgewichte zwischen Cu(II) und Thiosalicylsäure (TSA) wurden spektrophotometrisch in wäßrigem Ethanol (17.08 mol% Ethanol) beiI=0.1M (NaClO₄) und 25±0.1°C untersucht. Analyse der Extinktions-pH-Kurven lieferte die Gleichgewichte in Lösung und die Stabilitätskonstanten der gebildeten Komplexe. Eine einfache, schnelle und empfindliche Methode zur Bestimmung von Spurenmengen von Kupfer wird vorgestellt. Der Einfluß einer großen Anzahl von Fremdionen wurde getestet. Die Methode wurde erfolgreich zur Analyse einiger Testmischungen sowie zur Kupferbestimmung in eisenfreien Legierungen eingesetzt.

     

Spectrophotometric determination of some analgesic and anti-inflammatory agents with 3-methyl-2-benzothiazolinone hydrazone hydrochloride

Simple and sensitive Spectrophotometric methods for the determination of pentazocine, naproxen, oxyphenbutazone, analgin, amidopyrine and mefenamic acid, based on the formation of a coloured species with MBTH on oxidation with Ce⁴⁺ or Fe³⁺, are described.     

Spectrophotometric determination of zinc in copper-base alloys with TAN

TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×10⁴ l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml).     

Spectrophotometric determination of iron (II) using a highly sensitive chromogenic reaction of 4-(2-benzothiazolylazo)pyrocatechol

4-(2-Benzothiazolylazo)pyrocatechol (BTAPC), a new organic reagent, reacts with Fe(II) to form a stable, water-soluble, violet, positively charged, binary complex over a pH range of 6.3 to 6.8. Some water-miscible organic solvents and surfactants have solubilization and sensibilization effects. In 40% acetone-water medium at 25 °C, a (ionic strength) value of 0.1 and a pH value of 6.5, the ratio of Fe(II) to BTAPC in the complex is 1 2 with an apparent stability constant of 1.97 × 10⁹ and two absorption peaks at 535 and 615 nm. If the absorbance is measured at 615 nm, not only the sensitivity is high (₆₁₅ = 1.10 × 10⁵ 1 · mol^–1 · cm^–1) and the contrast () is large (90 nm), but also the selectivity is fairly good. Beer's law is obeyed for iron along the range of 0 to 16 g per 25 ml. The satisfactory results have been achieved after applying the method to the determination of traces of iron in water.     

Spectrophotometric and derivative spectrophotometric determination of nickel with hydroxynaphthol blue

The reaction of nickel(II) cation with hydroxynaphthol blue (HNB) in aqueous media at pH 5.2–6.0 results in a red complex that is stable for at least 2h. Beer's Law is obeyed up to 3.2 g/ml of nickel(II) with an apparent molar absorptivity of 1.38 × 10⁴l/mol/cm at 563 nm. This paper proposes procedures for nickel determination by ordinary and first-derivative spectrophotometry. The results demonstrate that the linear dynamic range is 0.08–3.20 g/ml with a limit of detection of 23 ng/ml for ordinary spectrophotometry, compared with 21–800 ng/ml and 6 ng/ml, respectively, for first-derivative spectrophotometry. Calcium(II), magnesium(II), barium(II), strontium(II), cadmium(II), lead(II), manganese(II), bismuth(III) and molybdenum(VI) ions do not interfere for at least 1001 mass ratios. The main interferents are cobalt(II), titanium(IV), aluminium(III), mercury(II) and copper(II). The interferences of titanium(IV), aluminium(III), zirconium(IV) and iron(III) can be masked by fluoride and mercury(II) and copper(II) with thiosulfate or thiourea. The derivative method is applied to nickel determination in standard brasses and the results demonstrate that there is no significant difference between the results and certified values at the 95% confidence level.     

Spectrophotometric determination of some antipsychotic phenothiazines

Thioridazine hydrochloride reacts with sodium nitrite and antimony(III) potassium tartrate in the presence of hydrogen peroxide to give a yellowish orange colour having maximum absorbance at 420 nm. The reaction is specific for antipsychotic phenothiazines with 1 g/ml as visual limit of identification and provides a basis for a new Spectrophotometric determination. The colour reaction obeys Beer's Law from 0.01 to 1.25 mg/10ml thioridazine. The standard deviation does not exceed 0.050 mg/10 ml. The method is successfully applied to pure and pharmaceutical preparations of antipsychotic phenothiazines, as well as to urine samples. The quantitative assessment of tolerable amounts of other drugs is also studied.     

Rapid and selective chelatometric titration of aluminium in non-ferrous alloys

A rapid chelatometric method for the determination of Al (4–20%) in magnesium, copper and chromium-aluminium-iron alloys is proposed. HEDTA is used as titrant and Zn solution as back-titrant, with hydrazidazol as indicator. Mn(II), Cu(II), Cd, Zn, Pb, Co(II), Ni, Hg(II), Fe(III), Bi, Cr(III), Sb(III), Ce(III), La, Sn(IV), Ti(IV), Zr and Mo(VI) do not interfere. High selectivity is achieved by a combination of group separation, masking and interference correction. The coefficient of variation varies from 0.2 to 1%.     

Spectrophotometric determination of tin in copper-based alloys using pyrocatechol violet

In the present paper, a new procedure using Pyrocatechol Violet (PCV) for the determination of tin in copper-based alloys is proposed. The use of HEDTA as masking agent allowed tin to be determined in the presence of large amounts of copper, without any separation procedure. The method is more selective than previous methods. Cetyltrimethylammonium bromide (CTAB) and Tween-20 are used to increase the stability of the system.

The method can be applied directly to an acidic solution of Sn(IV) in the range 2.0–60.0 μg with a final volume of 50 ml. The pH is adjusted to 2.0 ± 0.2 with glycine buffer and, after 30 min, the absorbance is measured at 660 nm. Al(III), Cd(II), Co(II), Mg(II), Ca(II), Mn(II), Ni(II) and Pb(II) do not interfere at the 500 mg level; 20 000 μg of Cu(II) and 400 μg of NaCl can be present. The interference at 100 μg of Fe(III) can be masked with ascorbic acid. Bi(III), Sb(V), Ti(IV), Mo(VI), EDTA, tartrate, citrate and iodide interfere. The proposed method was used for tin determination in several copper-based alloys and a comparison of the analytical results with certified values indicates that the procedure provides accurate and precise results.     

Spectrophotometric determination of iron in zirconium metal and in zirconyl chloride

Iron, present in zirconium metal or in zirconyl chloride, may be determined spectrophotometrically in 1 : 1 hydrochloric acid solution without prior separation from the zirconium. In a 1 : 1 hydrochloric acid solution, at the solubility limit of zirconyl chloride (0.28 g zirconium per 25 ml), 20 p.p.m. of iron may be detected.When smaller amounts of iron are to be determined (4 p.p.m.), a larger starting sample (5 g) of zirconium is crystallized from a 3 : 1 hydrochloric acid solution which reduces the lower limit of detection of iron to 4 p.p.m.     

Spectrophotometric and titrimetric determination of gallium in minerals and ores using semimethylthymol blue

The composition, overall stability constant and molar absorptivity of the chelate of gallium(III) ion with semimethylthymol blue, SMTB, were determined spectrophotometrically in acetate buffer (pH 4.5–5). A violet Ga(SMTB) chelate was formed with logarithmic overall stability constant of 18.0±0.1 (I=0.1) and molar absorptivity of 4.25×10⁴l mol^–1cm^–1 (_max 580 nm). SMTB is proposed as a new reagent for the spectrophotometric determination of micro-molar amounts of gallium(III). The colour development depends on time, temperature, pH and buffer species. The interference of different cations, anions and organic acids on gallium(III) determination was also investigated. Beer's law was obeyed for 3.5–31.3 gGa(III)/25ml (0.14–1.25 g ml^–1). SMTB was used for the spectrophotometric determination of gallium in different grade minerals and ores and the results were of acceptable error and relative standard deviation. Comparison between the two suggested methods and atomic absorption spectrometry for Ga(III) determination was carried out.     

Spectrophotometric and spectrodensitometric determination of paracetamol and drotaverine HCl in combination

Thin-layer chromatography, first derivative, ratio spectra derivative spectrophotometry and Vierordt's method have been developed for the simultaneous determination of paracetamol and drotaverine HCl. TLC densitometric method depends on the difference in Rf values using ethyl acetate:methanol:ammonia (100:1:5 v/v/v) as a mobile phase. The spots of the two drugs were scanned at 249 and 308 nm over concentration ranges of 60-1200 microg/ml and 20-400 microg/ml with mean percentage recovery 100.11%+/-1.91 and 100.15%+/-1.87, respectively. The first derivative spectrophotometric method deals with the measurements at zero-crossing points 259 and 325 nm with mean percentage recovery 99.25%+/-1.08 and 99.45%+/-1.14, respectively. The ratio spectra first derivative technique was used at 246 and 305 nm with mean percentage recovery 99.75%+/-1.93 and 99.08%+/-1.22, respectively. Beer's law for first derivative and ratio spectra derivative methods was obeyed in the concentration range 0.8-12.8 and 0.4-6.4 microg/ml of paracetamol and drotaverine HCl, respectively. Vierordt's method was applied to over come the overlapping of paracetamol and drotaverine HCl in zero-order spectra in concentration range 2-26 and 2-40 microg/ml respectively. The suggested methods were successfully applied for the analysis of the two drugs in laboratory prepared mixtures and their pharmaceutical formulation. The validity of the methods was assessed by applying the standard addition technique. The obtained results were statistically agreed with those obtained by the reported method.     

钒酸铵氧化-分光光度法测定盐酸氯丙嗪

在磷酸介质中,钒酸铵与盐酸氯丙嗪反应生成红色氧化产物,其最大吸收波长为524nm;据此建立了测定盐酸氯丙嗪含量的钒酸铵氧化-分光光度法,并将其用于直接测定药物制剂中的盐酸氯丙嗪.结果表明,当盐酸氯丙嗪的浓度处于10.0～100mg/L和100～360mg/L范围内时,被测定体系的吸光度与盐酸氯丙嗪的浓度之间呈良好的线性关系;线性回归方程分别为A=-0.061 69+0.010 05c(mg/L,r=0.998 8)、A=0.494+0.004 43c(mg/L,r=0.998 8),检出限为1.96mg/L,相对标准偏差为0.29%,回收率为94.9%～102.9%.