Rapid and Sensitive Spectrophotometric Determination of Hafuium(IV) With 2-(5-Bromo-2-Pyridylazo)-5-Diethylaminophenol

Abstract

Hafnium(IV) reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the pH range 3.3–11.0 to yield a sparingly soluble red-coloured chelate that can be dissolved with Triton X-100. Effect of initial pH of metal ion and order of addition of reagents was studied in detail. The 1:3 complex adheres to Beer's law over the concentration range 0.02–1.12 μg/ml of Hf(IV), has a molar absorptivity 1.33x10⁵ 1 mol^?1cm^?1, Sandell sensitivity 1.3 ng cm^?2, formation constant (log K) 11.94 and the method had a relative standard deviation of ± 1.5%. Effect of 60 diverse ions on the determination of hafnium(IV) was studied. This fairly selective method is the most sensitive so far reported for the spectrophotometric determination of hafnium(IV).     

Spectrofluorimetric determination of iridium(IV) traces using 4-pyridone derivatives

A new spectrofluorimetric determination of iridium(IV) with 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) or 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) is reported. Iridium(IV) react with HX or HY and chelates were extracted into chloroform or dichloromethane. The organic phase showed fluorescence. The fluorescence measurements to quantify iridium were carried out in its fluorescent band centred at λ_ex=373 nm and λ_em=480 nm. Under optimal conditions, the calibration graphs were linear over the concentration range of 0.1-7.6 μg ml⁻¹ of iridium for Ir(IV)-HX and 0.1-5.8 μg ml⁻¹ for Ir(IV)-HY with a correlation coefficients of 0.999 and 0.992 and relative standard deviation of ±1.1%.The method is free from interference by Rh(III) and Pt(IV), which normally interfere with other methods. Iridium can be determined in the presence of 300-fold excess of rhodium(III) and 10-fold excess of platinum(IV).The method was applied successfully to the determination of iridium in some synthetic mixtures and mineral sample gave satisfactory results.     

Synergistic extraction and spectrophotometric determination of palladium(II), iron(III), and tellurium(IV) at trace level by newly synthesized p-[4-(3,5-dimethylisoxazolyl)azophenylazo]calix(4)arene

A spectrophotometric method for the determination of palladium, iron and tellurium from nitric acid media after extraction of their p-[4-(3,5-dimethylisoxazolyl)azophenylazo]calix(4)arene [DMIAPAC] complexes has been developed and possible synergistic effects have been investigated. Chloroform, carbon tetrachloride, cyclohexane, 1,2-dichloroethane, toluene and xylene were used as the diluents. The maximum enhancement was obtained in the presence of 30% 1,2-dichloroethane. The trace amounts of metals were determined spectrophotometrically. Beer’s law obeyed in the concentration range of 5.0–95.0 μg, 8.0–120.0 μg and 10.0–140.0 μg/10 mL of the final solution of palladium, iron and tellurium, respectively. The molar absorptivities (l mol^?1cm^?1) and Sandell’s sensitivities (μg cm ^?1) were calculated: Pd(II) = 1.73 × 10⁴ and 0.0061; Fe(III) = 1.08 × 10⁴ and 0.0052; Te(IV) = 1.67 × 10⁴ and 0.0077. Ten replicate analyses containing 20 μg of Pd(II), 12.5 μg of Fe(III) and 32 μg of Te(IV) gave mean absorbance of 0.326, 0.242 and 0.418 with relative standard deviation of 0.36, 0.65 and 0.82% for Pd(II), Fe(III) and Te(IV), respectively. The interference of various ions was studied and optimum conditions were developed for the determination of these metals in certain alloys and synthetic mixtures.     

Extraction—spectrophotometric determination of palladium(ii) with 2-nitroso-5-diethylaminophenol

An extraction—spectrophotometric determination of palladium(II) with 2-nitroso-5-diethylaminophenol is described. Complex formation and extraction of the complex with chloroform are possible with aqueous phases of about 2.5 M sulfuric acid. The molar absorptivity of the complex is 4.38 X 10⁴ l mol^-1 cm^-1 at 486 nm. Few of the common ions interfere at concentrations of 10^-4–10^-3 M; more than 10^-5 M Ir(IV), 10^-5 M W(VI), 5 × 10^-6 M Au(III) and 10^-6 M iodide cause negative errors. The method can be applied to the determination of palladium in catalysts for automobile exhaust purifiers.     

Selective solid-phase extraction and separation of trace gold, palladium and platinum using activated carbon modified with ethyl-3-(2-aminoethylamino)-2-chlorobut-2-enoate

Activated carbon was chemically modified with ethyl-3-(2-aminoethylamino)-2-chlorobut-2-enoate to obtain a material for selective solid-phase extraction of trace Au(III), Pd(II) and Pt(IV) prior to their determination by inductively coupled plasma atomic emission spectrometry. Experimental conditions such as effects of pH, shaking time, sample flow rate and volume, elution and interfering ions were studied. The ions Au(III), Pd(II) and Pt(IV) can be quantitatively adsorbed on the new sorbent from solution of pH 1. The adsorbed ions were then eluted with 0.1 mol L^?1 hydrochloric acid and containing 4% thiourea. Many common ions do not interfere. The adsorption capacity of the material is 305, 92, and 126 mg g^?1 for Au(III), Pd(II) and Pt(IV), respectively, and the detection limits are 5, 11 and 9 ng mL^?1. The relative standard deviation is less than 3.0% (n?=?8) under optimum conditions. The method was validated by analyzing two certified reference materials and successfully applied to the preconcentration and determination of these ions in actual samples with satisfactory results.

1-(2-氨乙基)吡咯烷树脂的合成及其对贵金属的吸附

研究了试剂摩尔比、反应温度、反应时间对1-(2-氨乙基)吡咯烷树脂合成的影响规律.此树脂的功能基含量2.74 mmol/g树脂,对Au(Ⅲ)、Os(Ⅳ)、Pt(Ⅳ)、Ir(Ⅳ)、Ru(Ⅲ)、Pd(Ⅱ)的吸附容量分别高达950、520、436、418、314、302 mg/g树脂.FT-IR、元素分析表征了树脂结构.测定了吸附速率曲线,配位比,表观吸附活化能△E_(Au)=6.4、△E_(Pt)=33.7kJ/mol.XPS研究了吸附机理.     

Synergistic solvent extraction of copper, cobalt, rhodium and iridium into 1, 2-Dichloroethane at trace level by newly synthesized 25, 26, 27, 28-tetrahydroxy-5, 11, 17, 23-tetra-[4-(N-hydroxyl-3-phenylprop-2-enimidamido) phenylazo] calix[4]arene

A spectrophotometric method for determination of copper, cobalt, rhodium and iridium ions from nitric acid media after extraction of these ions by 25, 26, 27, 28-tetrahydroxy-5, 11, 17, 23-tetra-[4-(N-hydroxyl-3-phenylprop-2-enimidamido) phenylazo] calix [4] arene (THPAC) has been developed and possible synergistic effect has been investigated. The maximum enhancement was obtained in the presence of 30% 1, 2-dichloroethane in DMF and 3M nitric acid. The trace amounts of the metal were determined spectrophotometrically. Beer’s law was obeyed in concentration range 5.0–10.0 μg, 6.0–120.0 μg, 12.0–100.0 μg, and 10.0–130.0 μg/10 mL of the final solution of copper, cobalt, rhodium and iridium, respectively. The molar absorptivities (l mol^?1 cm^?1) and Sandell’s sensitivities (μg cm^?1) were calculated: Cu (II) = 0.96 × 10^4, 0.0066; Co (II) = 1.13 × 10⁴, 0.0052; Rh (III) = 0.98 × 10⁴, 0.012; and Ir (III) = 2.03 × 10⁴, 0.0095, respectively. Seven replicate analyses containing of 20.0 μg of Cu (II), 24.0 μg of Co (II), 36.0 μg of Rh (III) and 25.0 μg of Ir (III) gave mean absorbance 0.302, 0.462, 0.344, 0.264; and relative standard deviation 0.65, 0.85, 1.10, 1.08%, respectively. The interference of various ions was studied and optimum conditions were developed for determination of metals in certain alloys, environmental, pharmaceutical and synthetic samples.     

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.     

Determination of platinum metals complexes with 2-(6-methyl-2-benzothiazolylazo)-5-diethylaminophenol by reversed-phase high performance liquid chromatography

The use of 2-(6-methyl-2-benzothiazolylazo)-5-diethylaminophenolas a precolumn derivatizing reagent in the reversed-phase high performance liquid Chromatographic separation and determination of Ru(III), Rh(III), Os(IV), Ir(IV), Pt(II), Co(II), Ni(II) and Cu(II) is reported. When the mobile phase consists of methanol-water (76/24% v/v) and 20 mmol/l (pH 5.0) acetate buffer, the eight complexes can be separated within 35 min on a C₈ column. The detection limits are Ru 7.0, Rh 5.1, Os 1.5, Ir 7.6, Pt 3.7, Co 0.62, Ni 0.14 and Cu 1.2 ng/ml, respectively, at a signal-to-noise ratio of 3. RSDs were typically Ca. 1%.     

Highly selective determination of rhodium(III) using silica gel surface-imprinted solid-phase extraction

A novel Rh(III)-imprinted amino-functionalised silica gel sorbent was prepared by a surface imprinting technique for preconcentration and separation of Rh(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher adsorption capacity and selectivity for Rh(III). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Rh(III) was 29.86?mg?g^?1 and 11.23?mg?g^?1, respectively. The imprinted Rh(III) was removed with 2?mL of 3% thiourea?+?2?mol?L^?1 HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Rh(III). The relatively selective factor (α_r) values of Rh(III)/Ru(III), Rh(III)/Au(III), Rh(III)/Pt(IV), Rh(III)/Ir(IV), Rh(III)/Pd(II) were 26.7, 39.0 29.2, 28.1, 43.7, respectively, which were greater than 1. The detection limit (3σ) of the method was 0.26?µg?L^?1. The relative standard deviation of the method was 1.79% for eight replicate determination of 10?µg of Rh³⁺ in 200?mL water sample. The method was validated by analysing standard reference material (GBW 07293), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace rhodium(III) in geological samples with satisfactory results.     

Spectrophotometic Determination Of Tin In Steels With2-(5-Nltro-2-Pyridylazo)-5-[N-n-Propyl-N-(3-Sulfopropyl)Amino]phenol

ABSTRACT

A highly sensitive azo dye, 2-(5-nitro-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (Nitro-PAPS), is used as a colorimetric reagent for the determination of tin(IV) content. Nitro-PAPS reacts with tin(IV) to form a water-soluble complex in 1.0 M acetic acid. Full color development is attained within 5 minutes, and maintains constant absorbance for at least 24 hours. The apparent molar absorptivity is 7.7 x 10⁴ dm³ mol^?1 cm^?1 at a maximum wavelength of 580 ran. Beer's law is obeyed for tin(IV) in the range of 0-1.2 μg ml^?1. The proposed method is successfully applied to the determination of trace amounts of tin in steels.     

Spectrophotometric determination of thorium in food using 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid

A new highly sensitive and selective chromogenic reagent, 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (1), was synthesized and applied to the spectrophotometric determination of trace thorium. In 5 mL of a 6 M perchloric acid medium, which greatly increases the selectivity, thorium reacts with 1 to form a 1: 2 green complex, having a sensitive absorption peak at 670 nm. Under optimal conditions, Beer’s law is obeyed over the range from 0 to 0.8 μg/mL Th(IV) and the apparent molar absorptivity is 2.09 × 10⁵ L/mol cm. It is found that, uranium(VI), Ti(IV), heavy rare earths, and most of other common metal ions do not interfere. The method has been tested on the determination of thorium in food samples with satisfactory results. The text was submitted by the authors in English.     

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrate and separate of trace amount of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ） and Ir (Ⅳ） ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0mL/min at pH2, and can also be desorbed with 15 mL of 4mol/L HCl 3% thiourea from the fiber column with recoveries of 96.5%-100%.The chelating fiber can be reused for ten times,the recoveries of these ions are still over 92%,and hundred to thousand times of excess of Fe(Ⅲ）,Al（Ⅲ）,Ca(Ⅱ），Mg（Ⅱ）,Ni(Ⅱ）,Mn（Ⅱ),Cu(Ⅱ），Zn(Ⅱ），and Cd(Ⅱ） cause no interference on the determination of the analyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES).The static saturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80mmol/g.The relative standard deviations for the determination of 20.0ng/mL each of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ）and Ir(Ⅳ） are in the range of 0.7%-3.0%.The recoveries for test from standard additions to real solution samples are between 96% and 100%.The concentration of each ion in powder sample detected by the method is in good agreement with the certified value.     

Addition and migration of ligands on a metal atom pair: The oxidative addition of hexafluoro-2-butyne to dinuclear dihydridoiridium(II) complexes [Ir(H)(μ-SBu-t)(CO)(PR3)]2(IrIr) (R = OMe or Me), and its dehydrogenation reaction when R = OMe

Dissymmetric dinuclear complexes (PR₃)(CO)(H)₂Ir(μ-SBu-t)₂Ir(C₄F₆(CO)-(PR₃) (III, R = OMe or Me), which can be described as the juxtaposition of dihydrido and alkyne adducts of Vaska's complex associated through thiolato bridges, were obtained by the reaction of hexafluoro-2-butyne with symmetric dinuclear dihydridoiridium(II) complexes, [Ir(H)(μ-SBu-t)(CO)(PR₃)]₂(]IrIr) (II). When R = OMe, after the loss of H₂, a molecular rearrangement leads to the symmetric dinuclear iridium(II) complex [Ir(μ-SBu-t)(CO)(P(OMe)₃)]₂(C₄F₆) (IV). A correlation between the presence of an intense absorption near 230 nm in the UV-visible spectra and the existence of a metal—metal bond is established. A sequence of formation, splitting and re-formation of the metal—metal bond is observed along the series of derivatives obtained from [Ir(μ-SBu-t)(CO)P(OMe)₃]₂ (I) to IV, via II and III.     

Ion flotation studies of the chlorocomplexes of some platinum group metals

The anionic chlorocomplexes of Au(III), Pt(IV), Pd(II), Ir(IV), Ir(III) and Rh(III) can be floated from aqueous solutions with cationic surfactants of the type RNR'₃Br. The flotation behavior of each metal is reported with respect to variations of hydrochloric acid and sodium chloride concentrations, the R and R' chain lengths, initial surfactant concentrations and initial metal ion concentrations. The flotation behavior of the metals is compared to the anion-exchange selectivity coefficients and a flotation selectivity sequence of Au(III) > Pt(IV), Ir(IV), Pd(II) > Ir(III) > Rh(III) is generally observed. Nearly 100% of Au(III), Pt(IV), Ir(IV) and Pd(II) can be recovered from dilute solutions using the ion flotation procedures.     

Thin-layer chromatographic separation of rhodium(III) and iridium(III, IV) by anion exchange

Summary The TLC behaviour of Rh(III), Ir(III) and Ir(IV) has been investigated in the two systems consisting of DEAE-cellulose or ECTEOLA-cellulose and 5 M HCl media containing H₂O₂. These systems, especially in combination with a simple chemical pretreatment of samples (with LiCl, HCl and H₂O₂), can effectively be applied to the complete separation of mixtures of Rh(III) and Ir(III) or Ir(IV) in a wide range of ratios and amounts (Rh: Ir=1100 to 1001).

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Dünnschicht-chromatographische Trennung von Rhodium(III) und Iridium(III, IV) durch Anionenaustausch

Zusammenfassung Das dünnschicht-chromatographische Verhalten von Rh(III), Ir(III) und Ir(IV) wurde in H₂O₂-haltiger 5 M salzsaurer Lösung auf DEAE-sowie ECTEOLA-Cellulose untersucht. In Kombination mit einer einfachen chemischen Vorbehandlung der Probe (mit LiCl, HCl, H₂O₂) kann eine wirkungsvolle Trennung von Rh(III) und Ir(III) oder Ir(IV) über einen weiten Konzentrationsbereich erzielt werden (Rh: Ir=1100 bis 1001).

     

ICP-OES determination of traces of Ru, Au, V and Ti preconcentrated and separated by a new poly(epoxy-melamine) chelating resin from solutions

A new poly(epoxy-melamine) chelating resin is synthesized from epoxy resin and used for the preconcentration and separation of traces of Ru(III), Au(III), V(V) and Ti(IV) ions from sample solutions. The ions analyzed can be quantitatively enriched by the resin at a flow-rate of 2 mL/min at pH 4, and quantitatively desorbed with 10 mL of 1 mol/L HCl + 0.2 g CS(NH₂)₂ at a flow-rate of 1 mL/min with recoveries of over 97%. The chelating resin can be reused 7 times without obvious loss of efficiency. Thousand-fold excesses of coexistent ions caused little interference during the enrichment and determination steps. The RSDs for the determination of 50 ng/mL Ru(III) and Au(III), 5.0 ng/mL V(V) and Ti(IV) were in the range of 1.5–4.5%. The recoveries of added standards in a real sample solution are between 96% and 100%, and the results for the ions analyzed in a nickel alloy sample are in good agreement with their reported values.     

Analysis of Metal Ions in Environmental Samples - III Synergistic Determination of Vanadium (V) As its Mixed Complex with N-0-Methoxyphenyl-2-Thenohydroxamic Acid and 3-(0-Carboxyphenyl)-1-Phenyltriazine-N-0Xide

Abstract

A highly sensitive, selective, and rapid method for the spectrophotometry determination of vanadium(V) at trace levels is described. The method is based on the selective extraction of vanadium(v) from strongly acidic (3–6 M hydrochloric acid) met ium with solution of N-0-methoxyphenyl-2- thenohydroxamic acid (0MTHA) in chloroform. The extract is then equilibrated with 3-(0-carboxyohenyl)-1-phenyltriazine-N-oxide(CPPTNO) at pH ? 1.5 and the resulting colour is measured at 445 nm. The colour system obeys Beer's law over the range 0–20 -μg/ml of vanadium; the molar absorptivityat the wavelength of maximum absorption (445 nm), and the Sandell sensitivity of the method are 1.1 × 10⁴1. mole^?1 cm^?1 and 0.005 μg/ml respectively.     

Anion-exchange TLC of rhodium(III) and iridium(III,IV) on DEAE-cellulose or ECTEOLA-cellulose

Summary The TLC behaviour and separation of Rh(III), Ir(III) and Ir(IV) has been investigated in the two systems composed of DEAE-cellulose or ECTEOLA-cellulose using 3 M or 5 M HCl containing NaClO₃ as solvent. These systems, especially in combination with a sample treatment with LiCl, HCl and H₂O₂ solutions, allow the clean-cut separations of Rh(III) from Ir(III) as well as Ir(IV), coexisting in an extremely wide range of amounts and ratios (RhIr=1500 to 2001). A brief discussion on the characteristic adsorption behaviour of Rh(III), dependent on the previous history of the sample solutions, is also included.

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Anionenaustausch-Dünnschicht-Chromatographie von Rhodium(III) und Iridium(III, IV) auf DEAE- oder ECTEOLA-Cellulose

Zusammenfassung Zur dünnschicht-chromatographischen Trennung von Rh und Ir wurden DEAE- bzw. ECTEOLA-Cellulose mit 3 M bzw. 5 M NaClO₃-haltiger Salzsäure als Lösungsmittel benutzt. Besonders in Verbindung mit einer Probevorbehandlung mit LiCl, HCl und H₂O₂ konnten mit diesen Systemen scharfe Trennungen von Rh(III), Ir(III) und Ir(IV) in einem weiten Konzentrationsbereich erzielt werden (RhIr=1500 bis 2001). Das Adsorptionsverhalten des Rh(III) in Abhängigkeit von der Vorbehandlung der Probelösung wird diskutiert.

     

Analytical applications of m- and p-phenylene-di(1-tetrazoline-5-thione) Gravimetric determination of ruthenium(lll) in presence of large amounts of rhodium (III)

A simple and rapid method is described for the gravimetric determination of ruthenium(III) with two new isomeric reagents, m-and p-phenylene-di(1-tetrazoline-5-thione). Solutions containing milligram amounts of ruthenium(III)on treatment with the acetone or alcohol solutions of the reagents at pH 5.5-7.0 give a quantitative yield of an intensely green insoluble 1:1 complex which can be easily filtered off and dried at 110-115 degrees . Amounts of ruthenium down to 0.5 mg can be determined with fairly good accuracy and precision. Even large amounts of rhodium do not cause any interference. The following cations interfere: Pd(II), Pt(IV), Au(III), Ir(IV), Bi, Fe(III), Cu(II), Hg(I), Hg(II), Pb, Cd, T1(I) and Ag.