Spectrophotometric determination of ruthenium(III) and iridium(TV) with 8-hydroxyquinoIine N-oxide

The spectrophotometric characteristics and the stability constants of the yellow to brown 1:1 and 1:2 complexes of platinum metals with oxine N-oxide (existing as chloro mixed-ligand complexes) have been investigated. Oxine N-oxide can be used as a spectrophotometric reagent for ruthenium(III) and iridium(IV).     

Colour reaction of platinum(II) with 5-(4-nitrophenylazo)-8-(p-toluenesulphonamido)-quinoline and its analytical applications

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of platinum. 5-(4-Nitrophenylazo)-8-(p-toluenesulphonamido)quinoline (NPTSQ) reacts with platinum(II) almost instantaneously in alkaline solution to form a violet-red 1:2 complex with an absorption maximum at 640 nm. Beer's law is obeyed over the concentration range 0-1 mug/ml platinum. The molar absorptivity is 1.37 x 10(5) 1.mole(-1).cm(-1). The method has been used for the determination of microamounts of platinum in catalysts and anode slime.     

A high-selectivity spectrophotometric reagent for determining platinum(IV)

The new reagent N-(m-Methylphenyl)-N'-(sodium p-aminobenzenesulfonate)-thiourea (MMPT) was synthesized and its structure was confirmed by elemental analysis, IR, UV and (1)HNMR spectra. The apparent molar absorptivities of usual ions were determined and the chromogenic reaction with microamounts of platinum(IV) was studied in detail. In the medium of an HAc-NaAc buffer solution, MMPT can react with platinum(IV) to form a green soluble complex. The maximum absorbance of the complex is at 754.4 nm (epsilon(754.4)=8.58 x 10(4) L.mol(-1).cm(-1)) and 332.8 nm (epsilon(332.8)=1.14 x 10(5) L.mol(-1).cm(-1)). Beer's law was obeyed for platinum concentrations in the range of 0 approximately 1.28 mg.L(-1); the correlation coefficient was r=0.9995. At 754.4 nm, over 50 ions did not interfere with the reaction. It is one of the simplest and most selective methods available. It was convenient and rapid and has been applied to the direct determination of Pt(IV) in ores and catalysts with satisfactory results.     

Pyrimidinethiol as a reagent for extraction separation of platinum metals and gold Determination of Pd(II), Os(VIII) and Ru(III)

The solvent extraction separation of Pt(IV), Pd(II), Os(VIII), Ru(III) and Au(III) from one another and also from Rh(III) and Ir(III) with 1-(2'-nitro-4'-tolyl)-4,4,6-trimethyl-(1H, 4H)-2-pyrimidinethiol has been investigated. Photometric procedures have been developed for the determination of Pd(II), Os(VIII) and Ru(III) with the same reagent. The reagent allows the enrichment of Pd(II) and Au(III) at the trace level from a large volume of aqueous medium even in the presence of base metals. The method can be used for the determination of platinum metals and gold in alloys.     

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.     

Extraction of gold(III), palladium(II), and platinum(IV) by 1-[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl]-1<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazole from hydrochloric acid solutions

The extraction of gold(III), palladium(II), and platinum(IV) with 1-[[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole from hydrochloric acid solutions into toluene has been studied. The extraction follows the anion-exchange mechanism. The concentration constants and thermodynamic parameters of the extraction reaction have been calculated. The reagent is proposed for use in the extraction of the sum of precious metals.     

Spectrophotometric determination of trace amounts of thallium with 7-(4,5-dimethylthiazolyl-2-azo)-8-hydroxyquinoline-5-sulphonic acid

A new reagent, 7-(4,5-dimethylthiazolyl-2-azo)-8-hydroxyquinoline-5-sulphonic acid, has been examined to evaluate its usefulness as a spectrophotometric reagent for thallium(III). A purple-red complex is formed in aqueous solution at pH 4-5 in the presence of cetylpyridinium chloride and the stoichimetric ratio is 1:2 (Tl:reagent). The apparent stability constant is 1.5 x 10(11). The effect of diverse ions has been studied and a method for determining trace amounts of thallium is proposed.     

A highly sensitive spectrophotometric determination of platinum(IV) using leuco xylene cyanol FF

A new, simple, highly sensitive and rapid spectrophotometric method has been described for the determination of platinum(IV). The method is based on the oxidation of leuco xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by platinum(IV) in sulfuric acid medium (pH 1.0-2.5), the formed dye shows an absorption maximum at 620 nm in acetate buffer medium (pH 3.0-4.5). The method obeys Beer's law over a concentration range of 0.3 to 2.6 micro g mL(-1) platinum, having molar absorptivity and Sandell's sensitivity of 5.1x10(4) L mol(-)(1) cm(-1) and 0.0038 micro g cm(-2), respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of platinum in pharmaceutical preparations, soil, natural water, plant material, platinum-containing catalyst, and synthetic alloy samples.     

1-(4-nitrophenyl)-3-(2-quinolyl) triazene as an extremely sensitive reagent for spectrophotometric determination of mercury

1-(4-Nitrophenyl)-3-(2-quinolyl)triazene has been synthesized, and used as an extremely sensitive reagent for the spectrophotometric determination of mercury by the decrease in the absorbance of the reagent at 490 nm and pH 9.0-10.8 in the presence of cetylpyridinium bromide. Beer's law is obeyed over the range 0-120 ng/ml Hg(II), the apparent molar absorptivity being 1.0 x 10(6) l.mole(-1).cm(-1). The effect of 69 ionic species or compounds has been examined. Trace mercury in waste water has been determined satisfactorily.     

Liquid anion exchanger study of gold (III) from aqueous halide media with N-n-octylaniline

N-n-octylaniline in xylene is used for the extractive separation of gold(III) from halide media. Gold(III) was extracted quantitatively with 10 ml of 2% reagent in xylene from 0.5-10 M and 0.5-8 M hydrochloric acid and hydrobromic acid, respectively. It was stripped from the organic phase with ammonia buffer solution (pH 10.1) and estimated spectrophotometrically with stannous chloride. The effect of metal ion, acids, reagent concentration and of various foreign ions has been investigated. Method is applicable to the analysis of synthetic mixtures containing platinum metals and alloy samples. The method is fast, accurate and precise.     

Disulphides of dithiophosphinic acids as analytical reagents-I Extractive spectrophotometric determination of palladium with some bis(dialkylthiophosphoryl)- and bis(diarylthiophosphoryl)disulphides

The disulphides of dithiophosphinic acids (DS) with the general formula R(2)P(S)SSP(S)R(2), where R = C(2)H(5), C(3)H(7), C(5)H(11), C(6)H(5) (I-IV) form coloured complexes of 1:3 stoichiometry with Pd(II). The absorption maxima and molar absorptivities are: a lambda(I) = 302 nm, epsilon(I) = 2.04 x 10(4) 1.mole(-1).cm(-1); lambda(II) = 305 nm, epsilon(II) = 2.58 x 10(4); lambda(III) = 303 nm, epsilon(III) = 2.60 x 10(4); lambda(IV) = 315 nm, epsilon(IV) = 3.25 x 10(4). The reaction takes about 3 min at room temperature, and the colour is stable for 24 hr. The influence of time, pH, reagent concentration, organic solvents and interferences have been studied. An extractive photometric method of determination of Pd(II) is described and applied to the determination of Pd(II) in a mixture of platinum metals.     

4-(9-fluorenylmethyloxycarbonyl)phenylhydrazine (FmPH): a new chromophoric reagent for quantitative monitoring of solid-phase aldehydes(1-3)

A direct method for quantifying solid-phase aldehydes has been developed, using a new reagent, 4-(9-fluorenylmethyloxycarbonyl)phenylhydrazine (FmPH). The FmPH reagent was synthesized in three steps (24% overall yield) from commercially available p-hydrazinobenzoic acid. Resin-bound aldehydes reacted quantitatively with FmPH, in the presence of trimethylorthoformate (TMOF) as a dehydrating agent, to form a highly conjugated, immobilized FmPH-hydrazone. Next, mild treatment of the hydrazone with an excess of piperidine-N,N-dimethylformamide (1:1) released the piperidine-dibenzofulvene adduct chromophore (epsilon(301nm) = 7800 M(-1) cm(-1)) from the support. FmPH quantitation of aldehydes proved to be a straightforward, sensitive, and reproducible technique for monitoring resin-bound aldehydes [albeit insufficiently reactive to allow reliable quantification of ketones]. The FmPH aldehyde assay is applicable to a range of solid supports, as demonstrated specifically for poly(ethylene glycol)-polystyrene (PEG-PS), aminomethylpolystyrene (AMP), and cross-linked ethoxylate acrylate resin (CLEAR).     

Synthesis of New Reagent 2‐Acetylthiophenethiocynate and its Use in Extraction of Pt(IV) Spectrophotometrically

2‐Acetyl thiophenethiocynate (ATT) was synthesized and its characterization study was carried out using elemental analysis, IR and NMR techniques. The new reagent was proposed as an extractant for the development of the extractive spectrophotometric method for determination of Pt(IV) metal. The reagent complexes with the metal to produce a yellow colored complex which was then extracted into ethyl acetate at pH 11.2–11.6 having an absorption maxima at 400 nm. The thermal study showed that the extraction reactions are exothermic in nature with the reagent, and the stoichiometric ratio of Pt(IV) to 2‐acetyl thiophenethiocynate in the organic phase was 1:2. The method permits separation and determination of platinum from real and binary mixtures. The separation of Pt(IV) from bivalent metal ions has been also studied.     

Extractive-spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone

The optimum conditions for the extractive-spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone have been established. Iron(II) reacts with this reagent at pH 2.0-7.5 to form an uncharged 1:2 (metal-to-ligand) complex, which can be extracted with toluene. Beer's law is obeyed over the range up to 0.84 mug/ml of iron(II) at 505 nm. The molar absorptivity of the extracted species is 5.83 x 10(4) 1.mole(-1).cm(-1). The proposed method is extremely sensitive and reproducible, and has been satisfactorily applied to the determination of total iron in freshwater samples by adding ascorbic acid to reduce iron(III).     

Extraction and separation studies of platinum(IV) with N-n-octylaniline

N-n-octylaniline in xylene is used for the extractive separation of platinum(IV) from acidic media. Platinum(IV) was extracted quantitatively with 10 ml of 3% reagent in xylene from 0.5 to 10 and 2.5 to 10 M hydrochloric and sulphuric acid, respectively. It was stripped from organic phase with water and estimated photometrically with stannous chloride. The effect of metal ion, acids, reagent concentration and of various foreign ions has been investigated. The method affords binary separation of platinum(IV) from iron(III), cobalt(II), nickel(II) and copper(II), and is applicable to the analysis of synthetic mixtures and alloys. The method is fast, accurate and precise.     

Spectrophotometric determination of microgram amounts of platinum

2-Ethyl-10-[3-(dimethylamino-2-methyl)propyl]phenothiazine hydrochloride (ethylisobutrazine hydrochloride) forms an orange-red complex with platinum(IV) at room temperature (26 ± 2 °C) in hydrochloric acid-sodium acetate buffer medium containing copper(II) ions. The complexation is complete within 10 min. The complex exhibits an absorption maximum at 529 nm with a molar absorptivity of 1.90 × 10⁴ liters mol^?1 cm^?1. Beer's law is obeyed over the concentration range 0.4–7.8 ppm of platinum. A 50-fold molar excess of the chromogenic reagent is necessary for the development of maximum color intensity. Job's method of continuous variation, the molar-ratio method, and the slope-ratio method indicate a 1:1 composition for the complex. The effects of pH, time, temperature, reagent concentration, order of addition of reagents, and interference of various ions are reported. The reagent has also been used successfully for the determination of platinum in minerals and alloys.     

Analytical application of a new thiazolylazo reagent, 2-(2-benzothiazolylazo)-5-dimethylamino-4-tolylarsonic acid Spectrophotometric determination of palladium

A new thiazolylazo reagent, 2-(2-benzothiazolylazo)-5-dimethylamino-4-tolylarsonic acid, has been synthesized and found to be a good chromogenic reagent for palladium. A 1:1 blue chelate (lambda(max) = 718 nm) is formed in a sulphuric or nitric acid medium. The molar absorptivity is 6.65 x 10(4) l. mole(-1).cm(-1). Beer's law is obeyed in the range 0-1.6 mug/ml Pd. Relatively large amounts of co-existing elements, including noble metals, can be tolerated.     

8-喹啉偶氮显色剂QADCB的合成及其分析性能的研究

报道了8-喹啉偶氮显色剂2-(8-喹啉偶氮)-5-二羧甲氨基苯甲酸(QADCB)的合成、提纯与鉴定,研究了其与Co(Ⅱ)、Ni(Ⅱ)、Fe(Ⅲ)的显色反应,对QADCB与Co(Ⅱ)的显色反应作了研究。在pH5.9的缓冲体系中,试剂与Co(Ⅱ)形成棕红色配合物,其最大吸收波长位于650nm,表观摩尔吸光系数为4.2×104L.mol-1.cm-1,钴量在0~20μg/25mL范围内符合比耳定律。方法简便、快速,选择性较好,已用于纯铜、维生素B12中微量钴的测定,结果满意。     

1-(4-硝基苯基)-3-(2-吡嗪)-三氮烯的合成及与镉(Ⅱ)的显色反应

报道了显色剂1-(4-硝基苯基)-3-(2-吡嗪)-三氮烯化合物的合成及其与镉(Ⅱ)的显色反应。在非离子表面活性剂Triton X-100存在下,pH 10.5的Na2B4O7-NaOH的缓冲介质中,该试剂能与镉(Ⅱ)与发生显色反应,形成摩尔比为4∶1的黄棕色配合物,配合物在波长453 nm处有最大吸收峰,表观摩尔吸光系数ε为6.90×104L.mol-1.cm-1,镉(Ⅱ)质量浓度在0~0.56μg/mL范围内遵守比尔定律。用拟定方法测不同废水中的镉(Ⅱ)。     

Palladium(II) Extraction from Hydrochloric Acid Solutions with 4-[(Hexylsulfanyl)methyl]-3,5-Dimethyl-1H-Pyrazole

Palladium(II) extraction from hydrochloric acid solutions with a novel weakly basic complexing reagent, 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1H-pyrazole, dissolved in chloroform was studied. Palladium(II) was found to be highly efficiently extracted from 0.1–3 mol/L HCl solutions. A coordination mechanism of palladium(II) extraction with a protonated form of the reagent via fast interphase transfer of ion associates was proposed. The composition of the extracted compound, [PdCl₂μ-L]_n (n > 2), was found, and the way of coordination of the reagent to metal ions through N(2) nitrogen atom and thioether sulfur atom was determined. The reagent can be recommended for concentrating palladium(II) and selectively separating it from platinum(IV), copper(II), nickel(II), and iron(III).