Extraction of iridium(IV) from hydrochloric acid media with crown ether in chloroform, and its determination by ICP–AES

A new method for the quantitative extraction and determination of trace amounts of iridium from hydrochloric acid media has been established based on the formation of an ion-association complex of iridium hexachloro anion IrCl₆ ^2– with dicyclohexyl-18-crown-6 (DC18C6) oxonium cation in chloroform, then determination by inductively coupled plasma atomic emission spectrometry (ICP–AES). The effect of various factors (solvent, acid concentration, crown ether, reagent concentration, shaking time, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of iridium has been investigated. The procedure was used to determine traces of iridium in palladium chloride and rhodium chloride.     

Separation of trace amounts of palladium (II) with crown ether from hydrochloric acid and potassium thiocyanate media

A new method for the separation of trace amounts of palladium from hydrochloric acid and potassium thiocyanate media has been established based on the formation of an ion-pair complex of palladium thiocyanate anion Pd(SCN)4(2-) and the cationic potassium complex of dicyclohexyl- 18-crown-6 (DC18C6) in chloroform. The effect of various factors (solvent, crown ether, potassium thiocyanate, hydrochloric acid, reagent concentration, shaking time, phase volume ratio, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of palladium has been investigated. The method can be combined with subsequent FAAS determination of palladium. The procedure was applied to determine palladium traces in chloroplatinic acid and rhodium chloride.     

Separation of trace amounts of palladium (II) with crown ether from hydrochloric acid and potassium thiocyanate media

A new method for the separation of trace amounts of palladium from hydrochloric acid and potassium thiocyanate media has been established based on the formation of an ion-pair complex of palladium thiocyanate anion Pd(SCN)₄ ^2– and the cationic potassium complex of dicyclohexyl-18-crown-6 (DC18C6) in chloroform. The effect of various factors (solvent, crown ether, potassium thiocyanate, hydrochloric acid, reagent concentration, shaking time, phase volume ratio, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of palladium has been investigated. The method can be combined with subsequent FAAS determination of palladium. The procedure was applied to determine palladium traces in chloroplatinic acid and rhodium chloride.     

Determination of platinum and iridium in reforming catalysts by second derivative and absorptiometric spectrophotometry

Summary Investigations on the spectrophotometric determination of platinum as a complex formed by tin(II)chloride in hydrochloric acid are reported. The determination of platinum was found to be interfered with by iridium, because it also forms a complex with tin(II) chloride. The features of the derivative absorption spectrophotometry for the quantitative determination of platinum and iridium was also studied. The analytical application of the method for the determination of platinum and iridium in catalysts was investigated.     

Extraction of rhodium and iridium with 4-(non-5-yl) pyridine

The extraction of rhodium and iridium with 4-(non-5-yl)pyridine (NP) was investigated. The rate of rhodium extraction increases with increasing concentration of NP and chloride ions. Spectroscopic studies indicate that the extracted species is an ion pair, RhCl^3?₆ 3HNP⁺. Under the conditions of optimum Rh extraction ([Cl^?]=3.7 M, [NP]=0.3 M, [H]=0.08 M), iridium is also extracted by NP with similar efficiency in the form of IrCl^3?₆ 3HNP⁺. The use of hypophosphorous acid to labilize rhodium results in a better extraction of rhodium without significantly changing the extraction of iridium. The efficiency and kinetics of the rhodium extraction improve with increasing chloride concentration. For [Cl^?] ? 3.7 M, [H₃PO₂]=2.5 M, [NP]=0.3 M and Ph ≈ 1.6, 82% of rhodium is extracted in 4 min and 95% in 30 min.     

Polyurethane foam for the extraction of rhodium and its separation from iridium

The rate of reaction of rhodium with thiocyanate at 90 degrees in the presence of lithium chloride or sufficient hydrochloric acid and the subsequent extraction of the metal from hydrochloric acid medium by polyether-type polyurethane foam was investigated. The effect of the chloride salts of different cations decreased in the order Li(+) > Na(+) > K(+) indicating that Rh(SCN)(6)(3-) is extracted through a simple solvent-extraction mechanism rather than the "cation-chelation" mechanism. The separation of rhodium and iridium was also examined and the results indicated that in the presence of 5-fold excess of iridium, an average of 95 +/- 2% iridium remained in the aqueous phase while an average of 93 +/- 2% rhodium was retained by the foam.     

Spectrophotometric determination of gallium (III) after solvent extraction of its chloro-complex with rhodamine B

In the speetrophotometric determination of Ga (III) after extraction of its chloro-complex with Rhodamine B, addition of sodium chloride has been found to be very effective for improving the sensitivity and broadening the operating conditions, e.g., a wider range of acid and dye concentration can be employed. The improvement is due to increased extraction of the gallium in the presence of sodium chloride.     

Studies on the extraction behavior of Zr(IV), Ce(III), Th(IV) and U(VI) from aqueous solutions of Arsenazo-I with HDEHP,HTTA, TDA and TCMA

The extraction behavior of Zr(IV), Ce(III), Th(IV) and U(VI) from aqueous solutions containing Arsenazo-I with the organic solvents tridodecylamine (TDA), 1-[thenoyl-(2)]-3-3-3-trifluoroacetone (HTTA), di(2-ethylhexyl) phosphoric acid (HDEHP) and tricaprylmethylammonium chloride (TCMA) in xylene has been investigated. Effect of hydrogen ion concentration in the aqueous phase, Arsenazo-I concentration, as well as the effect of solvent concentration on the extraction was studied. Some alternatives for separation of the elements studied were recommended enabling the spectrophotometric determination of these elements using Arsenazo-I without interference.     

Determination of total chlorine in waste oil

Summary A simple method has been developed to determine the concentration of organic chlorine in waste oil. The determination is based on the conversion of organic chlorine to inorganic chloride by reaction with sodium biphenyl followed by extraction with nitric acid and a mixture of nitric acid and water. The concentration of chloride is determined by direct potentiometry with an ion-selective electrode. The limit of determination amounts to 3·10^–5 mol·l^–1 chloride ions with a standard deviation of 3.5%. Different samples of waste oil have been analyzed and the results have been compared to those obtained by combustion in a H₂/O₂ flame followed by potentiometric titration with silver nitrate.     

铱(Ⅳ)-高碘酸钾-丁基罗丹明B体系催化光度法测定铱

研究了在磷酸－氯化钠介质中,痕量铱催化高碘酸钾氧化丁基罗丹明Ｂ（ＢＲＢ）褪色反应及其动力学条件,建立了高灵敏、高选择性痕量铱的新方法。测定的缄性范围为０．４￣３２μｇ／Ｌ,检出限为４．０×１０＾－７ｇ／Ｌ。对质量浓度２０μｇ／Ｌ Ｉｒ（Ⅳ）测定的相对标准偏差为３．１２％（ｎ＝１１）,考察了３０多种共存离子的影响,大多数常见元素不干扰,允许１００倍量Ａｕ、Ｐｄ、和６０倍量Ｐｔ、Ａｇ存在。本法已用于某     

HPLC determination and pharmacokinetic studies of salvianolic acid B in rat plasma after oral administration of Radix Salviae Miltiorrhizae extract

A precise and reproducible HPLC method has been established and validated for determination of salvianolic acid B (SalB) in rat plasma after oral administration of Radix Salviae Miltiorrhizae extract. Liquid-liquid extraction was adopted for the sample preparation. Separation was accomplished on a C(18) column with a linear gradient elution consisting of acetonitrile and aqueous phosphoric acid. Ultraviolet detection was at 280 nm. The method was validated over the concentration range 10.8-259.4 microg/mL using 1 mL of plasma. The assay was linear over this concentration range with a coefficient of variation less than 7%. The extraction recovery of SalB was within the range 71-83% with RSD 11%. The mean recovery of the internal standard was 84% (n = 6) with RSD of 5.6%. This method is suitable to determine SalB in plasma and to investigate the pharmacokinetics of SalB.     

Determination of crotonaldehyde in ethanol by differential pulse polarography

The extraction constant of gold bisdiethyldithiocarbamate chloride has been determined (log K' = 81.5± 0.7) by studying the competition from palladium in the extraction of gold with an excess of copper diethyldithiocarbamate in chloroform. Gold bisdiethyldithiocarbamate chloride is an ion pair which can dissociate: a dissociation constant of this compound has been determined by studying the influence of chloride concentration on the extraction of gold with the same reagent. In sulphuric acid medium, the low extraction ratio of gold observed cannot be attributed to extraction of gold bisdiethyldithiocarbamate sulphate as dependence on sulphate concentration has not been obtained. A program for the computation of this type of stability constant from extraction data for mixtures of cations and ligands is given.     

A new solvent extraction scheme for the separation of platinum,palladium, rhodium and iridium

A new scheme is proposed for the separation of platinum, palladium, rhodium and iridium in hydrochloric acid solutions, by solvent extraction. Platinum and palladium are complexed with 2-mercaptobenzothiazole and potassium iodide and simultaneously extracted into chloroform, thus separating them from rhodium and iridium. Palladium is separated from platinum by extracting its dimethylglyoxime complex into chloroform, while rhodium is separated from iridium by extracting its 2-mercaptobenzothiazole complex into chloroform after reduction with tin(II) chloride.     

Use of solid-phase extraction and high-performance liquid chromatography for the determination of triazine residues in water: validation of the method

A method for determination of some triazine residues in water has been developed. The method involves concentration with C18 solid-phase extraction cartridges followed by high-performance liquid chromatographic analysis using a C18 column with UV detection at 230 nm, a mobile phase of methanol-water (60:40, v/v) at pH 4.6 (phosphoric acid) and a flow-rate of 0.8 ml/min. After optimization of the extraction and separation conditions, the method was validated. The method can be used for determination of atrazine, simazine, cyanazine and ametryn in water, within the international limits of 0.1 microg/l.     

Solvent extraction separation of rubidium with a crown ether for neutron activation analysis in rock samples

The extraction behavior of rubidium with a crown ether has been studied and methods for the separation and determination of rubidium have been developed. Rubidium was separated with tetraphenylborate from sample solution, and then quantitatively extracted into nitrobenzene by 18-crown-6 from 0.05 mol/l picric acid (pH 6) and back-extracted by 6 mol/l hydrochloric acid. Rubidium was determined by the neutron activation method in rock samples.     

Determination of benzylpenicillin, oxacillin, cloxacillin, and dicloxacillin in cows' milk by ion-pair high-performance liquid chromatography after precolumn derivatization

A high-performance liquid-chromatographic method has been developed for the determination of five penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, oxacillin, cloxacillin, and dicloxacillin) at trace levels in commercially available milk samples. This method comprises extraction of the lipids with ethyl acetate, clean-up and concentration on a C-18 solid-phase extraction column, and derivatization with 1,2,4-triazole and mercury(II) chloride solution, pH 8, at 65 degrees C for 10 min. The derivatized compounds are eluted from a C-2 column with a mobile phase containing acetonitrile and phosphate buffer loaded with sodium thiosulfate and tetrabutylammonium hydrogen sulfate as ion-pairing reagent. The limit of determination was found to be 4 microg L(-1) milk for benzylpenicillin and 10 microg L(-1) for the others. This meets EU criteria according to decision No. 93/256/EEC.     

Bestimmung von iridiumspuren mit thiodibenzoylmethan mittels substöchiometrischer isotopenverdünnungs-analyse: Determination of traces of iridium with thiodibenzoylmethane by substoichiometric isotope dilution analysis

Determination of traces of iridium with thiodibenzoylmethane by substoichiometric isotope dilution analysisIridium(III or IV) reacts with thiodibenzoylmethane on heating at pH 6 to form a 1:3 complex, which can be concentrated by extraction into chloroform. Based on this reaction, a reproducible, selective determination of iridium is achieved by means of substoichiometric isotope dilution analysis, based on ¹⁹²Ir. The linear range is 1–11 nmol of iridium.     

Kinetics of iridium(III) catalyzed oxidation of benzaldehyde and <Emphasis Type="Italic">p</Emphasis>-nitrobenzaldehyde by cerium(IV) in aqueous acidic medium

Oxidation of benzaldehyde and p-nitro-benzaldehyde by cerium(IV) sulphate in aqueous sulphuric acid is strongly catalyzed by iridium(III) chloride. The complex formed between cerium(IV) and the organic substrate in the first equilibrium step gives another complex in the presence of iridium(III), which ultimately gives the corresponding aromatic acids as the product of oxidation. The order of the reaction follows first-order kinetics at low concentrations to zero order at higher concentrations of both the oxidant and organic substrate. The rate is directly proportional to the concentration of catalyst, but decreases sharply with increasing H⁺ ions and cerium(III) concentrations, while change in ionic strength of the medium or the concentration of acetic acid and Cl⁻ ions has no effect on the rate.     

Further study of extraction equilibrium of uranium(VI) with dicyclohexano-18-crown-6 and its application to separating uranium and thorium

In our publication (1), the extraction of uranium with dicyclohexano-18-crown-6 (mixed isomers) has been described. The extraction equilibrium of uranium(VI) from aqueous hydrochloric acid solution with dicyclohexano-18-crown-6 isomer A (Ia) and isomer B (Ib) in 1,2-dichloroethane is presented in this paper. The extracted species are found to be 1:2 (metal/crown) for Ia and 2:3 for Ib from slope analysis and direct determination of extracted complexes. The extraction equilibrium constants (Kex) have been determined at 25°C, and equal 29.5 for the former and 0.208 for the latter. It is concluded that Ia has stronger coordinate ability for uranium than Ib. The different orientation of the lone pairs of the oxygen atoms in both isomers will be taken into account for interpreting above results. The extraction of uranium(VI) with dicyclohexano-18-crown-6 (mixed isomers) or Ia from aqueous hydrochloric acid solution is effective and selective. In 0.1M crown ether-1,2-dichloroethane-6N HCl system, the separation factor U(VI)/Th(IV) exceeds 1000. The result can be taken in separating uranium and thorium.     

Solvent Extraction Separation of Iridium(III) from Rhodium(III) by N-n-Octylaniline

The use ofN-n-octylaniline for the extraction of iridium(III) from malonate media is studied at pH 8.5. Iridium(III) extracted in the organic phase was stripped with 2.0 M hydrochloric acid and was determined spectrophotometrically by the stannous chloride–hydrobromic acid method at 385 nm. The extraction system is studied as a function of the equilibration time, diluent, reagent concentration and diverse ions. Experimental data have been analyzed graphically to determine the stoichiometry of the extracted species. It was found that the extraction of iridium(III) proceeds by an anion exchange mechanism and transforms into the extracted species [RR"NH₂ ⁺Ir(C₃H₂O₄)₂ ^–]_org. The method is simple, rapid, and selective and has been devised for the sequential separation of iridium(III) from rhodium(III), not only from each other, but also from other accompanying Platinum Group Metals (PGMs), Au(III), and base metals.