Spectrophotometric determination of palladium with 2-mercaptobenzoxazole

A new spectrophotometric method for the determination of palladium is described using 2-mercaptobenzoxazole as reagent. The color reaction has a sensitivity of 0.08 μg of Pd per cm² for log I₀/I = 0.001 and obeys Beer's law from 2 to 40 p.p.m. The effects of pH, time, order of addition of the reagents, temperature and diverse ions were investigated. The procedure was applied to synthetic solutions containing palladium plus a variety of foreign ions.     

Spectrophotometric determination of palladium with 2-mercaptomethyl-benzimidazole

Summary A spectrophotometric method has been developed for the determination of palladium with 2-mercaptomethyl-benzimidazole. This involves extraction of the palladium complex into iso-amyl alcohol in presence of 0.3 to 2N hydrochloric acid and 0.45 to 1.4M ammonium sulfate. The color is very stable and is highly selective for palladium. At 380 nm it obeys Berr's law in the concentration range of 1 to 9g of Pd per ml; the optimum range being 4 to 8g. The sensitivity and molar absorptivity of the reaction are 0.019g of palladium per cm² and 5600±70 respectively. The continuous variation and molar ratio methods indicate that palladium forms 12 complex with the ligand.

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Zusammenfassung Eine spektrophotometrische Methode zur Bestimmung von Palladium mit 2-Merkaptomethylbenzimidazol wurde ausgearbeitet. Der Palladiumkomplex wird mit Isoamylalkohol in Gegenwart von 0,3- bis 2-n Salzsäure und von 0,45- bis 1,4-m Ammoniumsulfat extrahiert. Die Farbe ist sehr beständig und sehr selektiv für Palladium. Bei 380 nm entspricht die Färbung dem Beerschen Gesetz zwischen 1 und 9g Pd/ml; der optimale Konzentrationsbereich liegt zwischen 4 und 8g. Die Empfindlichkeit der Reaktion beträgt 0,019g Pd/cm²und die molare Absorption 5600±70. Die Untersuchung nachJob ergab für den Komplex das Molverhältnis Pd: Reagens= 12.

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Résumé On a mis au point une méthode spectrophotométrique pour le dosage du palladium par le mercaptométhyl-2 benzimidazole. Elle met en jeu l'extraction du complexe du palladium par l'alcool isoamylique en présence d'acide chlorhydrique 0,3 à 2N et de sulfate d'ammonium 0,45 à 1,4M. La coloration est très stable et bien sélective pour le palladium. A 380 nm, elle suit la loi de Beer dans le domaine de concentration de 1 à 9g de Pd par ml; le meilleur domaine s'étend de 4 à 8g. La sensibilité et l'absorbance molaire de la réaction sont respectivement de 0,019g de palladium par cm² et 5600±70. Les méthodes des variations continues et du rapport molaire indiquent que le palladium forme un complexe 1,2 avec le coordinat.

     

Spectrophotometric determination of microamounts of quercetin based on its complexation with copper(II)

The complexation process of the transition metal Cu(II) with quercetin was studied. The investigation was conducted spectrophotometrically in ethanol at the maximum absorption wavelength of 458.5 nm. Cu(II)—quercetin complex composition (1: 1) was determined using the Job, Harvey—Manning, and mole ratio methods. Complex stability constant was calculated by the Job and mole ratio methods and the respective logarithm values were 7.53 ± 0.25 and 7.44 ± 0.03. A new method for quantitative determination of the quercetin content in solution was developed in this work. At the optimal conditions quercetin was determined in concentrations ranging from 0.202 to 1.006 μg cm⁻³ with relative standard error of 2.5 % to 5.5 %. The lower detection limit was 0.067 μg cm⁻³. The method was found very accurate, reproducible, and sensitive, capable to determine microamounts of quercetin in pharmaceutical preparations.     

Spectrophotometric determination of manganese with 2-oximinocyclohexanone thiosemicarbazone

The 2-oximinocyclohexanone thiosemicarbazone forms, in basic medium, a violet complex with Mn(III) whose stoichiometry is 3:1 (reagent:Mn(III)). The molar absorptivity has a value of 3000 liters · mol⁻¹ · cm⁻¹. By means of the formation of this complex manganese can be determined between 9 and 400 μg with a relative error (95% confidence level) of 0.20%. The effect of foreign ions has been examined and the method has been applied to Mn(II) determination in Lincolnshire iron ore.     

Spectrophotometric determination of palladium with pyridine-2-aldehyde-2-quinolylhydrazone

A new, sensitive colorimetric procedure for the determination of microgram quantities of palladium(II) with pyridine-2-aldehyde-2-quinolylhydrazone is described. The reaction is practically instantaneous and not sensitive to variations in salt concentration. The platinum group metals do not interfere, and the analysis is possible with milligram amounts of these metals present.     

Spectrophotometric determination of rosmarinic acid in plant cell cultures by complexation with Fe2+ ions

A spectrophotometric method for determining rosmarinic acid (α-O-caffeoyl-3,4-dihydroxyphenyllactic acid) in unpurified methanolic extracts from Lavandula cell cultures is reported. It is based on a complexation reaction of rosmarinic acid with Fe²⁺ to give a blue-dark product with λ_max=572 nm and ?₅₇₃=3.82×10³ l mol^?1 cm^?1. The stoichiometry of the reaction and the optimal conditions for colour development are checked. The sensitivity and accuracy of this spectrophotometric method are compared with UV-spectral and HPLC methods for determining rosmarinic acid in plant cell cultures; similar results are obtained.     

Spectrophotometric determination of platinum with substituted pyrimidine-2-thiol

The yellow complex of Pt(IV) with 1-pyridyl-4,4,6-trimethyl-1H,4H-pyrimidine-2-thiol (PyTPT) which has maximum absorbance at 430 nm, is studied for the spectrophotometric determination of the metal. Molar absorptivity is 5000 liters mol^?1 cm^?1 and Sandell's sensitivity is 0.039 μg/cm². The determination of Pt(IV) (2.8–8.4 ppm) in the presence of diverse ions is described.     

热处理碳纸电极上VO2+/VO+2氧化还原动力学

在不同温度下热氧化处理碳纸, 用循环伏安、极化曲线和交流阻抗方法研究碳纸电极上VO2+/VO+2氧化还原动力学. 循环伏安和极化曲线结果表明, 随着热处理温度的升高, VO2+/VO+2氧化还原反应的速率常数及交换电流增大. 建立了VO2+/VO+2氧化还原反应的交流阻抗等效电路模型. 拟合结果表明, 热处理增大了碳纸电极表面的双电层电容, 减小了VO2+/VO+2氧化还原反应的电荷转移电阻. 用循环伏安和交流阻抗两种方法求得的VO2+和VO+2的扩散系数基本相同, 表明所构建的交流阻抗等效电路模型与电极反应过程相符合.     

Spectrophotometric determination of iron with 2-hydroxy-3-napthoic acid

2-Hydroxy-3-napthoic acid is presented as a new, highly sensitive and selective reagent for its colour reaction with ferric ion. The sensitivity of the reaction is 0.025 μg/cm² (SANDELL). The blue-coloured complex is maximally absorbed at 590 mμ and obeys Beer's law up to 24 p.p.m. of iron. The optimum range of concentration is from 4 to 20 p.p.m. of iron, where the percent relative analysis error per 1% absolute photometric error is 2.9. The composition of the complex, as evaluated by JOB's method and as verified by the Molar and Slope ratio methods, shows that in solution, the complex contains the iron and the reagent in a ratio of l : 1. The empirical formula of the complex is suggested to be [Fe(C₁₁H₇O₃)]⁺². The molar extinction coefficient is 2212 and the instability constant of the complex is about 4.29 ? 10^-4. Coloured ions or those ions that give coloured products are tolerated to a limited extent during the determination of iron.     

2,4-二氯苯基荧光酮体系分光光度法测定微量铋

研究了在十六烷基三甲基溴化铵(CTMAB)存在下,铋与2,4 二氯苯基荧光酮的显色反应条件,该体系最大吸收峰位于570nm,表观摩尔吸光系数为ε=1.48×105L·mol-1·cm-1。在0～0 68μg/mL范围内符合比尔定律。本法可用于胃药和合金中微量铋的分析。     

Spectrophotometric determination of chromium(III) with 2-hydroxybenzaldiminoglycine

A spectrophotometric method employing 2-hydroxybenzaldiminoglycine is proposed for the determination of chromium(III). The results of the determinations are compared with those obtained by the standard diphenyl carbazide method. The presently developed method is direct, simple, rapid, selective, sensitive and precise. The text was submitted by the authors in English.     

Spectrophotometric determination of cobalt and nickel with Pyridine-2-Aldehyde-2-Quinolylhydrazone

Pyridine-2-aldehyde-2-quinolylhydrazone (PAQH) is a selective and sensitive reagent for cobalt or nickel. The reagent reacts with only a few metals to give coloured complexes; with the exception of palladium, the cobalt chelate is the only complex relatively stable towards protons and PAQH is a very selective reagent for cobalt. In the presence of thioglycollic acid only nickel reacts with PAQH; the chelate is extracted with chloroform and its absorbance measured at 492 nm. The high molecular extinction coefficients (30·10³ and 51·10³) permit the determination of 0.2–2 p.p.m. of cobalt and 0.1–1 p.p.m. of nickel.     

Spectrophotometric determination of aluminium with stilbazo

The use of stilbazo as a spectrophotometric reagent for aluminium has been investigated. The reagent forms a stable coloured complex with aluminium showing an absorption maximum at 500 mμ. The system obeys Beer's law from 0.1–0.8 p.p.m. aluminium. The molar extinction coefficient and the stoichiometric composition of the coloured complex have been determined.     

Spectrophotometric determination of scandium with arsenazo

Arsenazo is used for the spectrophotometric determination of scandium in the range 10 to 50 μg. The absorbance is measured at 570 mμ and pH 6.1. A method is proposed for the successive determination of scandium and thorium. Scandium is separated from magnesium, calcium, rare earths, zirconium, fluoride, phosphate, and some other metals by extraction with TTA in xylene. Copper, aluminum, and iron(III) are removed by 8-quinolinol-chloroform extraction. Uranium(VI) is removed by anion exchange using hydrochloric acid. Thorium is separated from scandium by anion exchange using nitric acid.     

Spectrophotometric determination of titanium with salicylamidoxime

Summary A spectrophotometric method for determining small quantities of titanium by extraction of the yellow coloured titanium salicylamidoxime complex from an acetate buffer medium (Ph 4.5–7.0) with iso-butanol and measurement of the colour intensity at 400 m has been described. Beer's law is obeyed in the entire range of 0.25–15 g Ti per ml of the solvent. The effect of a large number of foreign anions and cations on the determination of titanium has been described.     

Spectrophotometric determination of platinum with o-phenylenediamine

Platinum(IV or II) reacts with o-phenylenediamine, at pH 6.5, to form light blue solutions having maximum absorption at 703 nm. The reaction, slow at room temperature, is complete in 3-4 min at temperatures near 100 degrees . Use of dimethylformamide in the solution prevents precipitation of the reaction product. The colour is stable for at least 24 hr. Effects of heating temperature and time, pH, reagent concentration, and other variables have been studied. The system conforms to Beer's law over the concentration range investigated. Optimum concentration range for measurement in 10-mm cells is 0.4-1.4 ppm of platinum; the molar absorptivity is 9.83 x 10(3) l. mole(-1). mm(-1). Interference from foreign ions has been evaluated, and methods for removal or masking of interferences have been tested. In the colour-forming reaction, platinum(IV) is reduced by the organic reagent to platinum(II), which is then complexed with the reagent. The metal : ligand ratio of 1 : 2 was indicated by solution spectrophotometric measurements, and was confirmed on the solid reaction product by elemental analysis and by mass spectrometric examination.     

Spectrophotometric determination of copper with cuproine

A study is devoted to the spectrophotometric determination of traces of copper with cuproine as reagent. After having determined the absorption spectrum of the complex, the authors have studied successively the partition coefficient water/ isoamyl alcohol ; the stability of the complex (colour); the influence of some factors: pH, foreign ions, temperature, the quality of isoamyl alcohol, excess reagent; and the validity of Beer's law. Two different calibration curves were determined, one based on complete extraction of the complex and the other based on an empirical method, which is very rapid. In both cases the mean square error is less than 1%.Finally, analysis methods were worked out for the determination of traces of copper in plants, animal tissues and blood, in water, in lamp-black and in steel.