Spectrophotometric determination of copper in plutonium metal with 2,9-dimethyl-1,10-phenanthroline

A spectrophotometric method for the determination of copper plutonium has been developed. The copper is complexed with neocuproine, extracted into chloroform, and the absorbance read at 457 mmu. The average relative error of the method is -1.4% with an average relative standard deviation of 4%.     

Spectrophotometric determination of vanadium with 1,10-phenanthroline

A simple and sensitive spectrophotometric method for the determination of vanadium based upon the reaction of vanadate with 1,10-phenanthroline in the presence of sodium dithionite in ammoniacal solution is described. The absorbance of the complex measured at 645 nm follows Beer's law for solutions containing 30-400 microg of vanadium in 100 ml of solution. A 10-fold excess of molybdenum, tungsten, phosphorus or chromium does not interfere. The molar absorptivity is 8.0 x 10(3) 1 mole(-1) cm(-1). The complex is shown to be tris-1,10-phenanthroline vanadium(II). The method has been applied successfully to the determination of vanadium in bauxite.     

Spectrophotometric determination of iron(II) with 1,10-phenanthroline in the presence of large amounts of iron(III)

A study was made to establish proper conditions for the selective determination of Fe(II) by the 1,10-phenanthroline method in the presence of large amounts of Fe(III). It was shown that fe(III) is effectively masked by fluoride. The pH of the solution to be masked should be below 2.5 in order to prevent acceleration by the fluoride of aerial oxidation of Fe(II).     

Spectrophotometric determination of iron in highly alkaline solution with 4-hydroxy-1,10-phenanthroline

4-Hydroxy-1,10-phenanthroline forms a stable tris-chelate with iron(II) in the range of alkalinity from pH 10 to 2M sodium hydroxide, with molar absorptivity 1.19 x 10(4) l.mole(-1).cm(-1) at 545 nm. The determination of iron is performed by adding the phenanthroline, stannous chloride, and iron-free sodium hydroxide to the sample to give pH > 13; stannite is the active reductant. Beer's law is obeyed over the iron concentration range from 1 x 10(-5) to 8 x 10(-5)M. Advantages over existing methods are the use of stannous chloride instead of sodium dithionite, which avoids the problem of turbidity, and the stability of the iron(II) chelate towards oxidation by air. The conditional reduction potential at pH 11 for the iron(III)/iron(II) complex couple is 0.39 V.     

邻二氮菲分光光度法测定盐酸氯丙嗪

在HAc-NaAc缓冲介质中,盐酸氯丙嗪(CPZ)能定量使Fe(Ⅲ)还原为Fe(Ⅱ),还原生成的Fe(Ⅱ)与邻二氮菲反应生成稳定的红色络合物,并且在一定范围内,CPZ的浓度和生成的红色络合物的吸光度呈良好的线性关系。据此,提出邻二氮菲-Fe(Ⅲ)体系测定盐酸氯丙嗪的新方法。在优化的实验条件下,盐酸氯丙嗪的质量浓度在0.040～15.00 mg/L范围内与吸光度呈现良好的线性关系,线性相关系数R=0.9995,摩尔吸光系数ε=2.8×104 L.mol-1.cm-1,检出限为0.020 mg/L。11次重复测定的相对标准偏差小于2.9%。该方法用于药物中盐酸氯丙嗪的测定,结果满意。     

Spectrophotometric determination of chlorpromazine hydrochioride by 1,10-phenanthroline

在HAc-NaAc缓冲介质中,盐酸氯丙嗪(CPZ)能定量使Fe(Ⅲ)还原为Fe(Ⅱ),还原生成的Fe(Ⅱ)与邻二氮菲反应生成稳定的红色络合物,并且在一定范围内,CPZ的浓度和生成的红色络合物的吸光度呈良好的线性关系.据此,提出邻二氮菲-Fe(Ⅲ)体系测定盐酸氯丙嗪的新方法.在优化的实验条件下,盐酸氯丙嗪的质量浓度在0.040～15.00mg/L范围内与吸光度呈现良好的线性关系,线性相关系数R=0.9995,摩尔吸光系数ε=2.8×104L·mol-1·cm-1,检出限为0.020mg/L.11次重复测定的相对标准偏差小于2.9％.该方法用于药物中盐酸氯丙嗪的测定,结果满意.     

Spectrophotometric determination of dissolved oxygen with tris(4,7-dihydroxy-1,10-phenanthroline)iron(II)

Tris(4,7-dihydroxy-1,10-phenanthroline)iron(II) reacts rapidly and quantitatively with dissolved oxygen in alkaline aqueous solution. In ammoniacal solution, the reaction is accompanied by the disappearance of the intense red colour of the iron(II) compound, which gives way to the pale gray, slightly-dissociated ion tris(4,7-dihydroxy-1,10-phenanthrolinefiron)(III). By measurement of the absorbance of a solution containing the ferrous compound before and after the injection of an oxygen-containing solution, the concentration of dissolved oxygen in the sample can be accurately determined in the range 1-20 ppm.     

Colorimetric determination of iron (III) with 1,10-phenanthroline

Summary A new procedure has been developed for the colorimetric determination of iron(III). It consists in the reduction of iron (III) in dilute sulphuric acid medium (0.1 to 1.0 N) with an excess of hypophosphite (1100) at room temperature using one or two drops of 0.1% PdCl₂ solution as catalyst, and then complexing the reduced iron with 1.10-phenanthroline.Iron (III) can also be reduced with phosphite using the PdCl₂ catalyst and boiling for 5 to 10 min on a hot plate. The molar concentration of phosphite is preferably kept 500 times that of ferric ion.

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Zusammenfassung Es wurde ein neues Verfahren zur colorimetrischen Bestimmung von Eisen(III) ausgearbeitet. Dabei wird das Eisen in verd. Schwefelsäure (0,1–1,0 n) mit einem Überschuß von Hypophosphit (1100) bei Zimmertemperatur unter Verwendung von ein oder zwei Tropfen 0,1%iger PdCl₂-Lösung als Katalysator reduziert und anschließend das zweiwertige Eisen mit 1,10-Phenanthrolin umgesetzt.Eisen(III) kann auch mit Phosphit reduziert werden, wenn man ebenfalls PdCl₂ als Katalysator verwendet und 5–10 min erhitzt. Die molare Konzentration des Phosphits soll dabei das 500fache von der des Eisens betragen.

     

Spectrophotometric determination of tannins in tea and beer samples with iron(III) and 1,10-phenanthroline as reagents

A simple and accurate spectrophotometric method is proposed for the determination of tannins in tea and beer samples based on the reduction of iron(III) to iron(II) by tannins at 80 degrees C for 20 min. The iron(II) was then reacted with 1,10-phenanthroline at pH 4.4 to form a coloured complex. Background correction could be effected by precipitating the tannins in the sample solution twice with gelatin and kaolin. Absorbance measurements were made at 540 nm and the calibration graph was linear from 0 to 5.5 micrograms ml-1 of tannic acid with a slope of 0.213 A p.p.m.-1. The precision for the determination of tannins in a tea sample containing 9.45% of tannins was 1.8%. Most of the ingredients commonly found in tea and beer samples do not interfere with the determination. Several tea and beer samples were analysed for their tannin content using the proposed method.     

Extraction—spectrophotometric determination of cadmium with diphenylcarbazone in the presence of 1,10-phenanthroline

The addition of 1,10-phenanthroline improves both the extraction and the spectrophotometric sensitivity of the determination of cadmium with diphenylcarbazone. Slope analysis suggests the formation of a 1:2:2 extracted species. The molar absorptivity is 9.4 × 10⁴ l cm^-1 mol^-1 at 536 nm and extraction is maximal at pH 8.2–9.8. Extraction is rapid and absorbances remain constant at room temperature for 48 h. Various divalent metal ions interfere.     

熔融萘萃取铁(Ⅱ)-4,7-二苯基-1,10-菲啰啉-四苯硼酸盐三元络合物光度法测定铁

研究了以熔融萘作为萃取剂,以4,7 二苯基 1,10 菲口罗啉作为显色剂,测定天然水中微量铁的分光光度法。在pH4的条件下,铁(Ⅱ)与4,7 二苯基 1,10 菲口罗啉和四苯硼酸盐能够形成红色三元络合物。在熔融萘存在下,此络合物可以迅速萃入熔融萘。将含有络合物的萘冷却、固化、分离,配制成25mL丙酮溶液,对其进行分光光度分析。实验表明,该络合物最大吸收波长为534nm,摩尔吸光系数和桑德尔灵敏度分别为2×104L·mol-1·cm-1和0.0025μg/cm2,铁(Ⅱ)的质量浓度在0～2 0μg/mL的范围内符合比耳定律。大多数常见离子不干扰测定。已应用于天然水中微量铁的测定。     

Flow-injection determination of copper(II) based on its catalysis on the redox reaction of cysteine with iron(III) in the presence of 1,10-phenanthroline

A redox reaction of cysteine with iron(III) proceeds slowly in the presence of 1,10-phenanthroline (phen). However, this reaction is accelerated in the presence of copper(II) as a catalyst, producing an iron(II)-phen complex (lambda(max)=510 nm). A sensitive spectrophotometric flow-injection method is proposed for the determination of copper(II) based on its catalytic action on this redox reaction. The dynamic range was 0.1-10 ng ml(-1) of copper(II) with a relative standard deviation of 1.0% (n=10) for 1.0 ng ml(-1) of copper(II) at a sampling rate of 30 h(-1). The detection limit (S/N=3) is 0.04 ng ml(-1). The proposed method was successfully applied to the determination of copper in river water as a certified reference material.     

Multicomponent determination of cobalt, copper, and iron with 1,10-phenanthroline by principal component regression modelling of spectrophotometric data

The rotational energy barriers were determined for twelve of the nineteen environmentally stable atropisomeric polychlorinated biphenyls (PCBs), viz. PCB 84, 131, 132, 135, 136, 144, 149, 174, 175, 176, 183, and 196, by thermal racemization of enantiomerically pure PCBs. The rate of racemization was primarily determined using off-line gas chromatography (GC) or high-performance liquid chromatography (HPLC), with permethylated cyclodextrin (PMCD) as the chiral selector. GC was used for PCB 84, 132, 136, 149, 174, and 176, while PCB 131, 175, and 196 were analyzed using HPLC. The remaining PCBs, i.e. PCB 144 and 183, were separated by HPLC using a Chiralpak OP(+) polymethacrylate column. Gibbs free energy of activation (Δ^‡G) was 176.6 to 184.8 kJ/ mole for tri-ortho PCBs. For tetra-ortho PCBs the Δ^‡G was estimated to be ∼246 kJ/mole. A buttressing effect of 6.4 kJ/mole was observed for tri-ortho PCBs that have one buttressing chlorine. Received: 19 October 1998 / Revised: 26 November 1998 / Accepted: 28 December 1998     

Spectrophotometric microdetermination of zinc in the presence of copper and iron

A simple, rapid, and sensitive procedure for the spectrophotometric microdetermination of zinc in the presence of iron and copper is proposed. Zinc is determined with DPPH (2, 2′-dipyridyl-2-pyridylhydrazone). The determination is carried out in aqueous solution. Iron and copper are reduced by ascorbic acid and masked with cyanide. The zinc-DPPH complex is formed at pH = 12 ± 0.2 and measured at 442 nm no more than 15 min after the addition of DPPH. Beer's law is obeyed at the concentration range of about 0.12 to 1.32 ppm of zinc.     

A new flow-injection determination of glucose based on the redox reaction of hydroquinone with iron(III) in the presence of 1,10-phenanthroline

A new spectrophotometric flow-injection (FI) method is proposed for the determination of glucose based on the redox reaction of hydroquinone with iron(III). When a glucose solution containing quinone is passed through the immobilized glucose oxidase column introduced in FI system, quinone is reduced to hydroquinone by glucose. In the presence of 1,10-phenanthroline (phen), iron(III) is then quantitatively reduced by hydroquinone to iron(II) followed by the formation of iron(II)-phen complex (λ_max=510 nm). An FI peak observed at 510 nm corresponds to the concentration of glucose. The wide dynamic range for glucose was obtained in the range of 1×10⁻⁶–1×10⁻³ mol l⁻¹ at a sampling rate of 24 h⁻¹ and the detection limit (S/N=3) was 5×10⁻⁷ mol l⁻¹. Relative standard deviations were 0.78, 0.44 and 0.23% (n=5) for 5×10⁻⁶, 5×10⁻⁵ and 5×10⁻⁴ mol l⁻¹ of glucose, respectively. The proposed method was successfully applied to the determination of glucose in control blood sera, human blood plasma and wine.     

Spectrophotometric method for the determination of ascorbic acid with iron (III)-1,10-phenanthroline after preconcentration on an organic solvent-soluble membrane filter

A solvent-soluble membrane filter is proposed for the simple and rapid preconcentration and spectrophotometric determination of ascorbic acid based on the reduction of 1, 10-phenanthroline (phen)-iron (III), which is collected on a nitrocellulose membrane filter as an ion-associate of the cationic complex of tri,phen-iron (II) [ferroin, Fe(phen)(2+)(3)] with an anionic surfactant (of dodecyl sulfate). The ion-associate collected is dissolved in a small volume of 2-methoxyethanol together with the filter. The colour intensity is measured at 510 nm against the reagent blank and is proportional to the content of ascorbic acid in the range 2.5-50 microg ascorbic acid in 5 ml of solvent with excellent reproducibility (RSD 3.2% for 200 microg 1(-1) ascorbic acid), the enrichment factor achieves 100-fold and detection limits better than 2.0 microg 1(-1) can be obtained. Diverse components of organic and inorganic compounds normally present in fruits, vegetable, beverages and urine do not interfere. The recoveries of the ascorbic acid added to the samples are quantitative.     

Spectrophotometric method for the determination of ascorbic acid with iron (III)-1,10-phenanthroline after preconcentration on an organic solvent-soluble membrane filter

A solvent-soluble membrane filter is proposed for the simple and rapid preconcentration and spectrophotometric determination of ascorbic acid based on the reduction of 1, 10-phenanthroline (phen)-iron (III), which is collected on a nitrocellulose membrane filter as an ion-associate of the cationic complex of tri,phen-iron (II) [ferroin, Fe(phen)²⁺₃] with an anionic surfactant (of dodecyl sulfate). The ion-associate collected is dissolved in a small volume of 2-methoxyethanol together with the filter. The colour intensity is measured at 510 nm against the reagent blank and is proportional to the content of ascorbic acid in the range 2.5–50 g ascorbic acid in 5 ml of solvent with excellent reproducibility (RSD 3.2% for 200 g 1^–1 ascorbic acid), the enrichment factor achieves 100-fold and detection limits better than 2.0 g 1^–1 can be obtained. Diverse components of organic and inorganic compounds normally present in fruits, vegetable, beverages and urine do not interfere. The recoveries of the ascorbic acid added to the samples are quantitative.     

Solvent extraction of anions with metal chelate cations-XVIII Spectrophotometric determination of maleic acid in the presence of fumaric acid by solvent extraction with tris(1,10-phenanthroline)iron(ii) chelate cations

A new colorimetric method is proposed for the determination of maleic acid. Among aliphatic dicarboxylic acids tested, maleic acid was found to be selectively extracted into nitrobenzene as the red ion-association complex (lambda(max) 516 nm) formed between the hydrogen maleate anion and the tris(1,10-phenanthroline)iron(II) cation. At least a 32-fold molar excess of tris(1,10-phenanthroline)iron(II) relative to maleic acid is needed and the optimal pH range is 3-5. A linear relationship is obtained over the concentration range 10(-5)-10(-4)M maleic acid. The relative standard deviation was 1.0 %. The colour intensity of the extract remains constant at room temperature for at least 24 hr. A large amount of fumaric acid, the trans-isomer of maleic add, is not extracted under the same conditions. This makes it possible to determine maleic acid in the presence of fumaric acid.     

Microdetermination of iron in plant tissue with 4,7-diphenyl-1,10-phenanthroline

A method is described for the wet digestion and colorimetric determination of small amounts of iron in plant tissues. The wet digestion uses a mixture of sulphuric and nitric acids instead of perchloric acid; a volumetric flask is used for weighing, digestion, and dilution. The iron complex with 4,7-diphenyl-1,10-phenanthroline is extracted into hexanol.