Trace Amounts Of Platinum Research Articles

Rapid spectrophotometric determination and extraction of platinum(IV) from pharmaceuticals assisted by 2-(2-(1-(thiophene-2-yl) ethylidene) hydrazinyl) benzoic acid (TEHBA).

It has been suggested that the chelating agent 2-(2-(1-thiophene-2-yl) ethylidene) hydrazinyl) benzoic acid (TEHBA) be utilized to extract, separate and measure platinum(IV) by UV-visible spectrophotometry at the microgram level. Following 5 min of heating the reaction mixture in a water bath, Pt(IV)-TEHBA complex formed. This complex was formed in the presence of potassium iodide solution with a molar absorption coefficient 1.9 × 103 dm3mol-1cm-1. At 420nm, the substance exhibited the greatest absorption. As Beer's law described, the Pt(IV)-TEHBA complex for platinum(IV) has a beer's range of 10-50μgcm-3. It was determined that the proportion ratio of the Pt(IV)-TEHBA complex was 1:1 after its extraction. Despite the investigation of interference from various ions, it was ascertained that the method exhibited selectivity exclusively towards platinum(IV). The trace amounts of platinum(IV) were extracted and quantified from synthetic mixtures representing alloys, binaries and ternary synthetic mixtures. The process of extracting platinum(IV) from pharmaceutical samples involves the implementation of a specific method. Moreover, the procedure exhibits a progressive segregation of palladium(II), platinum(IV) and nickel(II) while also boasting its ease of operation.

Nickel phosphide decorated with trace amount of platinum as an efficient electrocatalyst for the alkaline hydrogen evolution reaction

Electrocatalytic water-splitting is considered as a highly promising technology for the sustainable production of hydrogen.

The noble metal loading binary iron–zinc electrode for hydrogen production

The binary FeZn was electrodeposited on graphite surface for hydrogen evolution reactions. Then, zinc was leached from the surface by an etching method in alkaline solution. A trace amount of platinum and ruthenium electrochemically deposited on binary FeZn, respectively. All electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy and potentiodynamic polarization techniques in KOH solution. The surface structures were characterized by scanning electron microscopy and energy dispersive X-ray. The results show that etching process enhanced the surface area. The prepared electrodes exhibited much higher activity after noble metal loadings. It is seen from experimental research that the most active electrode is C@FeZn/Ru.

Highly active carbon supported palladium catalysts decorated by a trace amount of platinum by an in-situ galvanic displacement reaction for formic acid oxidation

Aimed at reducing platinum usage and improved catalytic activity for formic acid oxidation, a series of Pt decorated Pd/C catalysts are prepared by an in-situ galvanic displacement reaction between freshly prepared Pd/C ink and H2PtCl6 in an aqueous solution. The catalysts with 4 nm particle sizes and 20 wt.% loadings have been characterized by transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy (XPS). The electrochemical evaluations by cyclic voltammetry are conducted to test out the CO tolerance and catalytic activities. In addition to XPS analysis, a theoretical calculation has been attempted the first time to find out the surface Pd/Pt molar ratios. The decay rate of the catalysts has been evaluated by the percentage of the forward/backward peak current retained using the value at the 20th cycle divided by that in the first cycle. Compared with a Pd/C benchmark, all Pt decorated Pd/C register enhanced activity while the cost remains virtually unchanged. The optimized catalyst is found to have a Pd/Pt molar ratio of 75:1 but with 2.5 times activity relative to that of Pd/C.

Improved low-temperature activity of silver–alumina for lean NOx reduction – Effects of Ag loading and low-level Pt doping

This study focuses on the effect of silver loading and low-level platinum doping on the distribution of silver species, the hydrocarbon activation, and the low-temperature activity for lean NOx reduction over silver–alumina catalysts. Sol–gel prepared Ag/Al2O3 samples, with varying silver loading and doped with trace amounts of platinum, were evaluated as HC-SCR catalysts using n-octane as reductant in a synthetic gas-bench reactor. In addition, the samples were characterized using X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, and the specific surface area was determined using nitrogen sorption. The study shows that as the samples are doped with trace-amounts of platinum, the activity for lean NOx reduction at low temperatures is enhanced. The catalyst composition that displays the highest activity for NOx reduction is a 2wt% Ag/Al2O3 sample doped with 500ppm platinum. This catalyst displays the highest low-temperature activity, most likely owing to an increased ability to adsorb and partially oxidize the hydrocarbon reductant, which is attributed to the Pt doping. Adsorption of a higher amount of hydrocarbons could result in that a lower amount of reducing agent is required for Pt doped Ag–alumina catalysts as compared to un-doped ones, which is beneficial with respect to fuel efficiency.

Phase transfer catalyst assisted directly suspended droplet microextraction of platinum from geological and spent automobile converter samples prior to HR-CS AAS determination

A rapid phase transfer catalyst assisted directly suspended droplet micro-extraction (PTC-DSDME) procedure was developed for the separation and pre-concentration of hydrophilic ionic platinum from the digested geological and spent automobile converters prior to its determination by high resolution continuum source atomic absorption spectrometry (HR-CS AAS). The method is based on the formation of extractable hydrophobic species of anionic platinum with quaternary ammonium solubilising sites of a phase transfer catalyst in a bulk aqueous phase, in the presence of an acid mixture. The formed hydrophobic species are separated from the bulk aqueous phase and pre-concentrated into a micro-volume of suspended 1-undecanol droplet, avoiding the addition of an external chelating agent. Several factors influencing the extraction efficiency, such as the nature and volume of organic solvent, stirring rate, different PTCs and extraction time were evaluated and optimized. The proposed method was applied to synthetic samples, spent catalytic converters and geological samples. The spiked recoveries were in the range of 99–102%. Under the optimized conditions, a detection limit of 0.28 ng mL−1 and a good relative standard deviation of ±1.5% at 5.0 ng mL−1 were obtained (n = 6). The accuracy of the procedure was evaluated by analyzing Canadian certified reference materials such as PTC-1a copper–nickel sulphide concentrate and PTM-1a copper–nickel sulphide matte samples. The results showed that PTC-DSDME combined with HR-CS AAS is a rapid, sensitive, and low-cost procedure requiring minimum organic solvent and an efficient analytical method for the separation and determination of trace amounts of platinum from various matrices.

Development of Cloud Point Extraction for Simultaneous Extraction and Determination of Platinum and Palladium Using Inductively Coupled Plasma Optical Emission Spectrometry in Platinum-Palladium Spent Catalysts

A new on-line cloud point extraction system coupled to inductively coupled plasma optical emission spectrometry was designed for simultaneous extraction, preconcentration and determination of trace amounts of platinum and palladium in platinum-palladium spent catalysts. This was based on the complexation of the metal ions with 1,8-diamino-4,5-bis(hydroxyamino)anthraquinone reagent in the presence of non-ionic surfactant of Triton X-114. After phase separation, the surfactant-rich phase was diluted with concentrated HNO3 (70%, w/w); the analytes concentrations were determined by inductively coupled plasma-optical emission spectrometry. Several factors influencing the instrumental conditions and extraction were evaluated and optimized. Under the optimum conditions, the enhancement factors of the proposed method were 35.4 and 29 for platinum and palladium, respectively. The detection limits were 0.3 and 0.45 µ g L−1. Finally, the developed method was successfully applied to the extraction and determination of platinum and palladium in platinum-palladium spent catalysts samples and satisfactory results were obtained.

The Use of Algae Chlorella vulgaris Immobilized on Cellex‐T Support for Separation/Preconcentration of Trace Amounts of Platinum and Palladium before GFAAS Determination

The ability of green algae Chlorella vulgaris, immobilized on Cellex‐T support, for selective binding of platinum (Pt) and palladium (Pd) from acidic solutions (at pH range 1.5–1.8) has been demonstrated. The use of immobilized algae packed into a microcolumn (150 mg) in a flow mode provides good efficiency and reproducibility of the biosorption process (95.2 ± 0.4% for Pt and 99.3 ± 0.9% for Pd). The presence of seven interfering ions up to their 100 µg mL−1 concentration does not influence Pt and Pd retention on the column. The best efficiency of elution for both metals from the column was obtained with 0.3 mol L−1 thiourea (TU) in 1 mol L−1 hydrochloric acid used as a stripping reagent The detection limits obtained by the optimized method, followed by graphite furnace atomic absorption spectrometric detection for Pt and Pd, were 0.2 and 0.096 ng mL−1, respectively. The proposed method was applied for matrix separation and determination of Pt and Pd by graphite furnace atomic absorption spectrometry (GFAAS) in spiked tap water, wastewater, and grass samples.

Determination of Trace Amounts of Platinum, Palladium, Rhodium and Iridium in High Purity Iron by ICP-OES and ICP-MS after Separation by Coprecipitation with Tellurium

Trace amounts of Pt, Pd, Rh and Ir in an iron solution sample were separated by a reductive co-precipitation process using Te and tin(II) chloride, and determined by ICP-OES and ICP-MS. The recovery test of Pt, Pd, Rh and Ir added in the solution sample was carried out after co-precipitation. The recovery of Pt, Pd and Rh added in the solution sample (100 ng each) were almost 100% under the following conditions: the concentration of hydrochloric acid was adjusted to 0.5 mol.l-1 , and 2.0 mg Te as a co-precipitant and 2.5 g tin(II) chloride as a reductant were added. The suitable standing time for the co-precipitation was 3 hours. On the other hand, the recovery of Ir was about 90%. After co-precipitation with Te, the detection limits by ICP-OES are 0.085 μg.g-1 for Pt, 0.32 μg.g-1 for Pd, 0.099 μg.g-1 for Rh and 0.094 μg.g-1 for Ir, and those by ICP-MS are 3.9 ng.g-1 for Pt, 5.0 ng.g-1 for Pd, 1.6 ng.g-1 for Rh and 1.0 ng.g-1 for Ir.

Preconcentration of Trace Amounts of Platinum in Water on Different Sorbents

Three different sorbents for platinum preconcentration in water were investigated: alumina, silica gel with bonded aminopropyl groups and Cellex-T. The sorbents were tested in a microcolumn at the flow rate 3 ml/min. Elution was performed with 2.0 mol/l ammonia, 2.0 mol/l hydrochloric acid and 1.2 mol/l thiourea solution, respectively. The optimal enrichment factor was 400 for the alumina column, when the eluent volume was 25 μl. Satisfactory precision was obtained for all sorbents. As the detection technique was used either FAAS or GFAAS, depending on the concentration of platinum in the eluate.

Adsorptive stripping voltammetric measurements of trace amounts of platinum(II) and ruthenium(III) in the presence of 1-(2-pyridylazo)-2-naphthol

An extremely sensitive stripping voltammetric procedure for low level measurements of platinum (II, IV) or ruthenium (III, IV) is reported. The method is based on the interfacial accumulation of the platinum (II) or ruthenium (III)-1-(2-pyridylazo)-2-naphthol complex on the surface of a hanging mercury drop electrode, followed by the reduction of the adsorbed complex during the cathodic scan. The peak potential was found to be −0.8 V vs. Ag/AgCl electrode and the reduction current of the adsorbed complex ions of platinum (II) or ruthenium (III) was measured by differential pulse cathodic stripping voltammetry. The optimum experimental conditions were: 1.5×10−7 mol/l of 1-(2-pyridylazo)-2-naphthol solution of pH 9.3, preconcentration potential of −0.2 V, accumulation time of 3 min and pulse amplitude of 50 mV with 4 mV s−1 scan rate in the presence of ethanol-water (30% v/v) — sodium sulphate (0.5 mol/l). Linear response up to 6.4 × 10−8 and 5.1 × 10−8 mol/l and a relative standard deviation (at 1.2×10−8 mol/l) of 2.4 and 1.6% (n=5) for platinum (II) and ruthenium (III) respectively were obtained. The detection limits of platinum and ruthenium were 3.2×10−10 and 4.1×10−10 mol/l, respectively. The electronic spectra of the Pt(II) — PAN and Ru(III) — PAN complexes were measured at pH 9.3 and the stoichiometric ratios of the complexes formed were obtained by the molar ratio method. The effects of some interfering ions on the proposed procedure were critically investigated. The method was found suitable for the sub-microdetermination of ruthenium (IV) and platinum (IV) after their reduction to ruthenium (III) and platinum (II) with sulphur dioxide in acid media. The applicability of the method for the analysis of binary mixtures of ruthenium (III) and (IV) or platinum (II) and (IV) has also been carried out successfully. The method is simple, rapid, precise, and promising for the determination of the tested metal ions at micro-molar concentration level.

Determination of microgram amounts of platinum as dithizonate in the presence of palladium by second-derivative spectrophotometry

A derivative spectrophotometric method, based on digitised secondśderivative absorption spectra, has been developed for the determination of trace amounts of platinum in the presence of palladium (<1 mg), using their dithizonates in carbon tetrachloride. Comparison of the first-, second- and third-derivative spectra revealed that the best conditions for the determination of Pt were obtained using second-derivative spectrophotometry in the range 20 000–19 000 cm–1(500–526 nm). No interference from Pd in the determination of 0.1–2 µg of Pt at 19 510 cm–1(513 nm) was observed when the zero-crossing measurement technique was applied. Good precision and increased sensitivity were attained by a suitable choice of instrument parameters (wavelength scale expansion, scanning speed and integration time) and also by smoothing and recording of multiple spectra. The method was applied to the determination of trace amounts of Pt (about 1 × 10–4%) in preparations of palladium chloride (after preliminary separation of most of the Pd) with good precision and recovery.

Sensitive flotation-spectrophotometric determination of platinum based on systems with chlorostannate(II) and basic dyes

Sensitive flotation-spectrophotometric methods are based on the ion-associates formed by the anionic chlorostannate(II) complex of platinum with the basic dyes rhodamine 6G, Victoria blue B, Victoria blue 4R and Capri blue. The ion-associates finally formed are sparingly soluble in water; when shaken with a suitable organic liquid, they accumulate quantitatively at the phase boundary or on the wall of the separatory funnel. The compound with rhodamine 6G, separated and washed, is dissolved in acetone; those ones with the other basic dyes are dissolved in methanol. In the best method, with rhodamine 6G, the molar absorptivity is 2.8 × 10 5 l mol −1 cm −1; with the other dyes, the molar absorptivities are 2.0–2.45 × 10 5. Beer's law is obeyed over the range 0.08-0.6 μg Pt ml −1. The separated ion-associate formed with rhodamine 6G (R6G) is considered to have the formula [(R6G +) 3] [Pt(SnCl 5) 3- 5]. The effects of other platinum metals on the determination of platinum with rhodamine 6G were examined; some interference was found from palladium and rhodium. Trace amounts of platinum in palladium could be determined after separation of platinum by extraction with triphenylphosphine oxide in 1,2-dichloroethane.

Alkyl ketoximes as analytical reagents. VI

A study of the chloroform extraction of the platinum(IV), rhodium(III), iridium(IV), iridium(III) and platinum(II) chlorides after reaction with 4-heptanone oxime in 1.0M hydrochloric acid solution indicates that platinum(II) constitutes a major interference in the quantitative extraction of the palladium(II) chloride-4-heptanone oxime complex. Trace amounts of platinum(IV) and rhodium(III) are extracted. Iridium(IV) and iridium(III) constitute a minor interference.

Trace analysis for platinum in glasses by neutron activation

Trace amounts of platinum were determined in eight glasses. These glasses had been prepared under special conditions, and information on both the surface and interior platinum was desired. Previous microscopic examination of the glass samples had identified platinum on the surface of at least four of the samples. The platinum was analyzed by means of the nuclear reaction ▪ The 199Au product has a 3.15-day T 1 2 and E γ of 158 and 208 keV. Samples were irradiated in the NBSR for 2 h at 1.3·10 13 n cm -2 sec -1. After irradiation, the glasses were etched with aqua regia for the determination of surface platinum, and then dissolved in hydrofluoric and perchloric acids for the determination of interior platinum. The radioactive 199Au was separated from the matrix by spontaneous deposition on metallic zinc. Experimental sensitivities of 0.04 μg of platinum were obtained.

The determination of trace amounts of platinum in glass by colorimetry, spark-source mass spectrography and X-ray fluorescence spectrometry

Methods for the determination of less than 1 µg g–1 of platinum in glass have been investigated and evaluated. The p-nitrosodimethylaniline colorimetric method has been adapted to enable 0·2 µg g–1 of platinum to be determined on 2 g of sample, while the tin(II) chloride colorimetric method has been shown to be too insensitive to permit the determination of such low concentrations. Spark-source mass spectrography, while confirming the heterogeneous distribution of the platinum throughout the glass, has also been shown to be too insensitive for the direct determination of platinum in this matrix. An X-ray fluorescence procedure has been successfully developed to enable 0·5 µg of platinum in a 1-g sample of glass to be determined with a relative standard deviation of 10 per cent. The time required for the complete analysis is 3 to 4 hours.The proposed methods depend on the pre-concentration of platinum by co-precipitation with tellurium.

Spectrographic Determination of Platinum in Synthetic Fluor-Phiogopite

In growing crystals of synthetic fluor-phlogopite, a trace amount of platinum might be found in them because of the use of platinum vessel.A study is made on spectrographic method of determining platinum in fluor-phlogopite specimens heated in a platinum vessel.Standard samples are prepared by adding a certain amount of platinum to fluor-phlogopite which is free from platinum. As internal standards, Au, Ru and Os are examined by the moving plate method, and Ru is found suitable for the analysis.The sample is mixed with an equal amount of carbon powder which contained 200 ppm of Ru.D.C.arc discharge is used for the excitation.The line pair of Pt 3064.7A/Ru 2988.9 A is used and each line intensity is corrected by background effect.A working curve is obtained for the range between 5 and 500 ppm. Standard deviation in ten times repetition of excitation at each concentration is 10-45 per cent.Satisfactory results are obtained from actual fluor-phlogopite specimens.