Determination of platinum and rhodium in dust and plant samples using microwave-assisted sample digestion and ICP-MS

The platinum group elements (PGEs), particularly platinum, palladium and rhodium, are nowadays increasingly emitted into the environment from automotive catalytic converters. Thus, a method for the determination of PGEs (especially platinum and rhodium) in dust and plant samples was developed. The developed method was based on microwave-assisted sample digestion and inductively coupled plasma mass spectrometric (ICP-MS) determination. Spectral interferences in ICP-MS determination were corrected using mathematical correction equations based on signal ratio measurement. In addition, platinum and rhodium concentrations in the digested dust samples were also determined after Te coprecipitation without correction of the interferences. The results for platinum and rhodium in reference materials (NIST SRM 2557, recycled monolith autocatalyst and BCR-723, road dust) were in good agreement with the certified values. Preliminary results for the anthropogenic platinum and rhodium emissions in Oulu, northern Finland, based on dust and plant samples, indicated a common traffic-related source of these metals.     

Determination of palladium,platinum, and rhodium by HPLC with online column enrichment using 4-carboxylphenyl-thiorhodanine as a precolumn derivatization reagent

In the present work, 4-carboxylphenyl-thiorhodanine (CPTR) was synthesized. A new method for the simultaneous determination of palladium, platinum, and rhodium ions as metal-CPTR chelates was developed using rapid column high-performance liquid chromatography equipped with an online enrichment capability. Palladium, platinum, and rhodium ions were precolumn-derivatized with CPTR to form colored chelates. The Pd-CPTR, Pt-CPTR, and Rh-CPTR chelates can absorbed onto the front of the enrichment column (ZORBAX Stable Bound, 4.6 × 10 mm, 1.8 μm) when they are injected with a buffer solution of 0.05 M sodium acetate-acetic acid (pH 3.5) as mobile phase. After the enrichment had finished, by switching the six-port switching valve, the retained chelates were back-flushed by mobile phase and moved towards the analytical column. The chelate separation on the analytical column (ZORBAX Stable Bound, 4.6 × 50 mm, 1.8 μm) was achieved with 46% acetonitrile (containing 0.05 M of pH 3.5 sodium acetate-acetic acid buffer and 0.01 M tritonX-100) as mobile phase. The palladium, platinum, and rhodium were separated completely within 2 min. The detection limits (S/N = 3) of palladium, platinum, and rhodium are 1.4, 1.6, and 2.0 ng/L, respectively. The method was applied to the determination of palladium, platinum, and rhodium in water, urine, and soil samples with good results. The text was submitted by the authors in English.     

Simultaneous determination of palladium, platinum and rhodium by on-line column enrichment and HPLC with 5-(2,4-dihydroxyphenylazo)-rhodanine as pre-column derivatization reagent

In this paper, a new method for the simultaneous determination of palladium, platinum and rhodium ions was developed using a rapid column high performance liquid chromatography equipped with on-line enrichment technique. The palladium, platinum and rhodium ions were pre-column derivatized with DHAR to form colored chelates. The Pb-DHAR, Pt-DHAR and Rh-DHAR chelates could be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [ZORBAX Stable Bound, 4.6 x 10 mm, 1.8 microm] with a 0.05 mol L(-1) of phosphoric acid solution as mobile phase. After enrichment, and by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and traveling towards the analytical column. The separation of these chelates on the analytical column [ZORBAX Stable Bound, 4.6 x 50 mm, 1.8 microm] was satisfactory with 54% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of tritonX-100) as mobile phase. Palladium, platinum and rhodium were separated completely within 2 min. By on-line enrichment technique, the enrichment factor of 100 was achieved, and the detection limits (S/N = 3) of palladium, platinum and rhodium reaches 1.4 ng L(-1), 1.6 ng L(-1) and 2.0 ng L(-1), respectively. This method was applied to the determination of palladium, platinum and rhodium in water, urine and soil samples with good results.     

Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents

In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium and gold ions in the digested samples were pre-column derivatized with HNATR to form colored chelates. The Pd-HNATR, Pt-HNATR, Rh-HNATR and Au-HNATR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] with a buffer solution of 0.05 mol L(-1) phosphoric acid as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and travelling towards the analytical column. These chelates separation on the analytical column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] was satisfactory with 72% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of Triton X-100) as mobile phase. The palladium, platinum, rhodium and gold chelates were separated completely within 2.5 min. Compared to the routine chromatographic method, more then 80% of separation time was shortened. By on-line solid phase extraction system, a large volume of sample (10 mL) can be injected, and the sensitivity of the method was greatly improved. The detection limits (S/N=3, the sample injection volume is 10 mL) of palladium, platinum, rhodium and gold in the original samples reaches 1.4, 1.8, 2.0 and 1.2 ng L(-1), respectively. The relative standard deviations for five replicate samples were 2.4-3.6%. The standard recoveries were 88-95%. This method was applied to the determination of palladium, platinum, rhodium and gold in human urine, water and geological samples with good results.     

Studies on optimization of conditions for separating rhodium and platinum by cation-exchange

It has been established that, owing to the amphoteric properties of rhodium(III) hydroxide, by making a rhodium chloride solution alkaline (pH approximately 13) with sodium hydroxide and then acidifying to pH 2 with nitric acid it is possible to convert at least 99% of the rhodium into cationic forms. This fact is utilized for separation of rhodium(III) and platinum(IV) from chloride solutions on a sulphonic acid cation-exchanger in hydrogen form. Loss of rhodium in the separation process is < 1%. Platinum elution is complete. This method is suitable for separation of mixtures of rhodium and platinum (present in molar ratio between 1:200 and 20:1).     

Simultaneous Determination of Palladium,Platinum and Rhodium by On‐Line Column Enrichment and a Rapid Column High Performance Liquid Chromatography with 2‐Carboxyl‐1‐Naphthalthiorhodamine as Precolumn Derivatization Reagent

Abstract

In this paper, 2‐carboxyl‐1‐naphthalthiorhodamine (CNTR) was synthesized, and a new method for the simultaneous determination of palladium, platinum, and rhodium ions as metal‐CNTR chelates was developed using rapid column high performance liquid chromatography combined with on‐line enrichment. The palladium, platinum, and rhodium ions were precolumn derivatized with CNTR to form colored chelates. The Pb‐CNTR, Pt‐CNTR, and Rh‐CNTR chelates could be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column (ZORBAX Stable Bound, 4.6×10 mm, 1.8 µm) with a buffer solution of 0.05 mol/L sodium acetate–acetic acid buffer solution (pH 3.5) as mobile phase. After enrichment, and by switching the six ports switching valve, the retained chelates were back‐flushed by mobile phase and traveling towards the analytical column. The separation of these chelates on the analytical column (ZORBAX Stable Bound, 4.6×50 mm, 1.8 µm) was satisfactory with 54% methanol (v/v) in 0.05 mol/L sodium acetate buffer (pH 3.5) containing 1 g/L Triton X‐100 as mobile phase. Palladium, platinum, and rhodium were separated completely within 2 min. The detection limits (S/N=3) of palladium, platinum, and rhodium are 1.4 ng/L, 1.2 ng/L, and 1.8 ng/L, respectively. This method was applied to the determination of palladium, platinum, and rhodium in water, urine, and soil samples with good results.     

Simultaneous Determination of Platinum and Rhodium with Hydroxylamine and Acetone Oxime by Catalytic Adsorptive Stripping Voltammetry (CAdSV)

This paper describes a very sensitive catalytic adsorptive stripping voltammetry (CAdSV) procedure for the simultaneous determination of traces of platinum and rhodium in new supporting electrolyte containing hydroxylamine or acetone oxime and formaldehyde in sulfuric acid medium. Platinum and rhodium were pre‐accumulated simultaneously and after 120 s of accumulation time at 0.0 V, the achieved detection limits were equal 0.1 ng L^?1 and 0.2 ng L^?1 for platinum and rhodium respectively in the presence of acetone oxime and 0.6 ng L^?1 and 0.2 ng L^?1 for platinum and rhodium respectively in the presence of hydroxylamine. Described reagents were successfully applied to the determination of platinum and rhodium in plant material. Inductively coupled plasma mass spectrometry (ICP MS) was used as a reference method to the CAdSV measurements.     

Countercurrent extraction separation of some platinum group metals

Distribution coefficients were determined for the partitioning of the chloro-complexes of platinum, palladium, rhodium, and iridium between tributyl phosphate and various concentrations of hydrochloriic acid. Theoretical calculations based on the experimentally determined distribution coefficients indicated that a seventeen stage countercurrent extraction apparatus would resolve mixtures of platinum and palladium, platinum and rhodium, and rhodium and iridium.Mixtures of platinum and palladium, and platinum and rhodium were resolved in a fashion predicted by theory. Mixtures of rhodium and iridium were not completely resolved.     

Comparison of Microwave-Assisted Digestion Methods and Selection of Internal Standards for the Determination of Rh, Pd and Pt in Dust Samples by ICP-MS

Different temperature-pressure controlled microwave-assisted digestion methods were compared for the digestion of dust samples prior to the determination of rhodium and platinum by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained for platinum and rhodium in the digested reference material (BCR-723, road dust) were generally in good agreement with the certified values. However, the determination of matrix elements (Zn, Rb, Sr, Y, Hf and Pb) showed clear differences between the digestion methods. In addition, different internal standards were compared in the determination rhodium, palladium and platinum by ICP-MS. According to the results, even serious non-spectral interferences can be corrected by choosing a suitable internal standard or combination of internal standards.     

钯、铑和铂的同时分光光度测定

贵金属混合物光度分析常需分离,同时测定的报导亦少见。本文提出了一种不用分离,不用萃取,不用解联立方程,灵敏、简便同时分光光度测定三种贵金属的方法。     

Spectrophotometric determination of noble metals with tin(II) in bromide solutions

In presence of tin(II) bromide, noble metals give coloured products which are suitable for spcctrophotometric determinations. The colours are red (platinum), yellow-orange (rhodium), yellow-brown (palladium), yellow (iridium) and violet (gold) They are extracted, except for gold, with isoamyl alcohol Platinum, rhodium and palladium can be separated from irdium, and rhodium and platinum from palladium. Rhodium and platinum can be determined simultaneously.     

Simultaneous Determination of Palladium, Platinum and Rhodium by On-Line Column Enrichment and HPLC with 4-Hydroxy-1-Naphthalthiorhodanine as Pre-Column Derivatization Reagents

In this paper, 4-hydroxy-1-naphthalthiorhodanine (HNTR) was synthesized, and a new method for the simultaneous determination of palladium, platinum and rhodium ions as metal-HNTR chelates was developed using rapid column high-performance liquid chromatography combined with on-line enrichment. The palladium, platinum and rhodium ions were pre-column derivatized with HNTR to form colored chelates. The Pb-HNTR, Pt-HNTR and Rh-HNTR chelates could be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [ZORBAX Stable Bound, 4.6 × 10 mm, 1.8 μm] with a buffer solution of 0.05 mol L⁻¹ sodium acetate-acetic acid (pH 4.0) as mobile phase. After enrichment, and by switching the six-ports switching valve, the retained chelates were back-flushed by mobile phase and traveling towards the analytical column. Separation of these chelates on the analytical column [ZORBAX Stable Bound, 4.6 × 50 mm, 1.8 μm] was satisfactory with 68% acetonitrile (containing 0.05 mol L⁻¹ of pH 4.0 sodium acetate-acetic acid buffer salt and 0.1% of tritonX-100) as mobile phase. Palladium, platinum and rhodium were separated completely within 2 min. The detection limits (S/N = 3) of palladium, platinum and rhodium are 1.2 ng L⁻¹, 1.5 ng L⁻¹ and 1.8 ng L⁻¹, respectively. This method was applied to the determination of palladium, platinum and rhodium in water, urine and soil samples with good results.     

超微量铂丶铑连续催化极谱测定及其催化波机理的探讨

For simultaneous determination of ultramicro amounts of platinum and rhodium the optimum condition has been described as 1.5N H2SO4-1.2% NH4Cl-0.0012M (CH2)6N4-0.003% N2H4XH2SO4. Both platinum and rhodium produce hydrogen catalytic waves with peak potential at-1.03 V and - 1.27 V (vs. S. C. E.) and the peak height of differential wave in single-sweep polarograph is directly proportional to the concentration of the metals in the range from 0.05 ppb to 1.0 ppb for platinum and from 0.0025 ppb to 0.1ppb for rhodium, respectively. The influence of other platinum group metals and some base metals on the height of catalytic waves has been examined. It has been shown that the method is very selective. It is applied even at 200:1 or at 1:10 (Pt:Rh). The mechanism of the catalytic waves has been discussed. The catalytic waves of both platinum and rhodium are due to "surface catalytic wave of hydrogen". The wave of rhodium can be attributed to catalytic discharge of hydrogen ion by the complex (Rh(CH2O)2Cl4)-. One of the ligands, formaldehyde, is the product of hydrolysis of hexamethylenetetramine. The wave of plainum can be attributed to catalytic discharge of hydrogen ion by the complex (PtACl5)-, where a denotes intermediate product (a substance containing CH2=N group) formed during the hydrolysis of hexamethylenetetramine. The role of hydrazine sulfate in catalytic system has been shown. Hydzazine can react with formaldehyde to from (CH2=N)2 which promotes the growth of platinum catalytic wave and in this way the concentration of formaldehyde in the system can be controlled.     

Ion exchange equilibria in simultaneous extraction of platinum(II,IV) and rhodium(III) from hydrochloric solutions

Regularities of sorption extraction of platinum(II, IV) and rhodium(III) by anion exchangers of various physical and chemical structure in the presence of hydrochloric media were studied. It is established that AM-2B, Purolite A 500, and Purolite S 985 ionites adsorb complex anions of platinum metals employing mixed mechanism. A high affinity of the studied anionites for the studied complex anions of platinum and rhodium is established.     

On the re-assessment of the optimum conditions for the determination of platinum, palladium and rhodium in environmental samples by electrothermal atomic absorption spectrometry and microwave digestion

The experimental conditions for the determination of platinum, palladium and rhodium by graphite furnace atomic absorption spectrometry (GFAAS) are re-assessed. A certified material (BCR-723) was used as a working sample and analyzed using various extraction and atomization procedures in order to find the optimal experimental conditions that enable the quantitative and reproducible detection of platinum, palladium and rhodium in environmental matrices. Evidently, literature observations regarding the atomization conditions were proven fairly adequate. However, the provision of the optimum extraction conditions revealed several parameters that lie behind the reported uncertainties. The appropriate combination between extraction conditions and atomization programs afforded a considerable improvement in the recoveries and analytical features of platinum, palladium and rhodium determination with GFAAS. Cross-examination of the analytical data with various CRMs (certified reference materials) was used to validate the robustness of the method in heterogeneous matrices bearing different element levels. Under the optimum experimental conditions the method permits the determination at concentrations as low as (LOD(3S/N)) 1.9 ng g(-1), 0.45 ng g(-1) and 0.6 ng g(-1) for Pt, Pd and Rh, respectively affording recoveries in the range of 93-101%. The method was successfully applied to the assessment of Pt, Pd and Rh accumulation in real road dust and soil samples in Greece.     

二氧化硅-聚硅氧烷负载硫杂-15-冠-5铂、铑配合物的合成及其催化硅氧化性能

6－(ω'-十一碳烯氧甲基)-1-硫杂-4,7,1O,13-四氧杂环十五烷与三乙氧基硅烷进行硅氢加成,产物依次以气相法二氧化硅固载、氯亚铂酸钾或三氯化铑络合,合成了相应的二氧化硅-聚硅氧烷负载硫杂-15-冠-5-铂、铑配合物,并研究了它们在烯烃与三乙氧基硅烷的硅氢加成反应中的催化性能.结果表明,二者均为硅氢加成反应的高效催化剂.     

Preparation of Colloidal Transition Metals in Polymers by Reduction with Alcohols or Ethers

Colloidal dispersions of rhodium, palladium, osmium, iridium, and platinum are prepared by refluxing the methanol-water solutions of rhodium(III) chloride, palladium(II) chloride, osmium(VIII) oxide, sodium chloroiridate, and chloroplatinic acid, respectively, in the presence of poly(vinyl alcohol) as a protective colloid. The preparations of colloidal dispersions of rhodium are successful in the presence of vinyl polymer with polar group such as poly(vinyl alcohol), polyvinylpyrrolidone, or poly(methyl vinyl ether). Polyethyleneimine, gelatin, polyethylene glycol), and dextran are ineffective as the protective colloid. Water-soluble primary alcohols such as methanol and ethanol, water-soluble secondary alcohols such as 2-propanol, and water-soluble diethers such as 1,4-dioxane are available as reductants for preparation of the colloidal dispersion of rhodium. The average diameters of metal particles in the colloidal dispersions of palladium, rhodium, platinum, iridium, and osmium in poly(vinyl alcohol) are determined by electron microscopy to be 53, 40, 27, 14, and < 10 Å, respectively. The particle size distribution in each colloidal dispersion is sharp within 50 Å wide. The particles in the colloidal dispersions of both iridium and osmium are highly dispersed with no aggregation, while in the colloidal dispersions of rhodium, palladium, and platinum, there exist aggregates of 5-15, 5-30, and 100-200 particles, respectively. Colloidal dispersions of rhodium, palladium, osmium, and platinum are effective as catalysts for hydrogenation of cyclohexene at 30.0°C under atmospheric hydrogen pressure.     

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.     

贵金属冶金物料中微量钯、铂、铑的双波长分光光度法同时测定的研究

本文提出了用二苄基二硫代乙二酰胺（ＤｂＤＯ）为显色剂分光光度测定铑的方法，并进一步研究了该试剂与钯、铂的反应，从而建立了可在一个试样中同时测定该三元素的方法。在２～３ｍｏｌ／ＬＨＣ１溶液中，钯与ＤｂＤＯ在室温显色，用氯仿萃取并用８．４ｍｏｌ／ＬＨＣ１振荡有机相，然后在４５４ｎｍ测定。在萃余液中加入ＳｎＣｌ＿２，并在沸水浴中加热，使铂、铑的ＤｂＤＯ络合物生成，再用氯仿萃取，８．４ｍｏｌ／ＬＨＣ１振荡有机相，以双波长分光光度法同时测定。其中铂用双波长系数倍率法（λ′＿２＝５２１ｎｍ，λ′＿１＝５００ｎｍ，Ｋ＝２．５６３），铑用双波长等吸收波长法（λ＿２＝４００ｎｍ，λ＿１＝５４６ｎｍ）。铂和铑的含量为１：５或５：１时互不干扰。     

The Catalytic Isomerization of Terminal Carbon–Carbon Double Bonds in Liquid Crystalline Polyesters at Hydrosilation with 1-(1′-Arylethoxy)-1,1,3,3-Tetramethyl Disiloxanes

In the present article, we report on the synthesis and investigation of the hydrosilylation of liquid crystalline compounds with terminal carbon–carbon double bonds in aliphatic tails mediated by complexes of rhodium (I) and platinum (II). New liquid crystalline compounds based on terephthaloyl-bis-4-oxybenzoate with terminal carbon-carbon double bonds in aliphatic tails were synthesized. The introduction in aliphatic tails of polar and light polarizible fragments lead to a decrease of mesomorphogenic ability-resulting compounds. The hydrosilylation of liquid crystalline compounds with terminal carbon-carbon double bonds in aliphatic tails with 1-(1′-arylethoxy)-1,1,3,3-tetramethyl disiloxanes mediated by complexes of rhodium (I) and platinum (II) was investigated. The main process in these conditions was the isomerization of olefin fragments.