Determination of platinum and palladium in road dust after their separation on immobilized fungus by electrothermal atomic absorption spectrometry

A flow solid phase extraction procedure based on biosorption of Pt(IV) and Pd(II) on Aspergillus sp. immobilized on cellulose resin Cellex-T was proposed for the separation and preconcentration of Pt and Pd before their determination by electrothermal atomic absorption spectrometry (ETAAS). The analytical conditions including sample pH, eluent type, flow rates of sample and eluent solutions were examined. The analytes were selectively retained on the biosorbent in acidic medium (pH 1) and subsequently eluted from the column with 1 mL of thiourea solution (0.25 mol L^− 1 thiourea in 0.3 mol L^− 1 HCl). The reproducibility of the procedure was below 5%. The limit of detection of the method was 0.020 ng mL^− 1 for Pt and 0.012 ng mL^− 1 for Pd. The method validation was performed by analysis of certified reference materials BCR-723 (tunnel dust) and SARM-76 (platinum ore). The developed separation procedure was applied to the determination of Pt and Pd in road dust samples by ETAAS.The applied biosorbent is characterized by high sorption capacity: 0.47 mg g^− 1 for Pt and 1.24 mg g^− 1 for Pd.     

Monitoring of the exposure to platinum-group elements for two Italian population groups through urine analysis

It is well recognized that automobile catalytic converters are the main source of Pd, Pt and Rh (also called platinum-group elements (PGEs)) in an urban atmosphere. Over recent years, urinary biomonitoring of PGEs has gained considerable importance in assessing the individual human exposure to these elements. This paper reports the concentration ranges of PGEs in the urine of 257 Italian subjects, aged between 23 and 88 years. Subjects were selected on the basis of standardized criteria in two different Italian cities, so as to represent a small urban area surrounded by an essentially rural environment and characterized by low automobile-traffic density (Foligno) and a large urban area with almost constant high-traffic conditions (Rome). The determination of PGEs was performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) after 1:4 (v/v) dilution of the samples. The 5th and 95th percentiles for PGEs in urine of subjects living in Foligno were the following (in ng l⁻¹): Pd 1.99-17.2, Pt 0.24-3.08 and Rh 0.53-14.8. The 5th and 95th percentiles in the urine of subjects from the area of Rome were (in ng l⁻¹): Pd 0.71-17.0, Pt 0.49-8.13 and Rh 4.10-38.6. Platinum and Rh median concentration values showed large and significant differences (P<0.0001) between the two urban settings considered (0.52 and 3.50 ng l⁻¹ for Pt and Rh in Foligno, respectively, and 1.70 and 12.85 ng l⁻¹ for Pt and Rh in Rome, respectively). On the other hand, no striking differences were found in the Pd concentration (median value of 6.02 ng l⁻¹ in Foligno versus 7.79 ng l⁻¹ in Rome). The sex variable correlates only with Pd concentration (P=0.05), pointing out that in males concentrations are higher than in females.     

Elimination of interferences in determination of platinum and palladium in environmental samples by inductively coupled plasma mass spectrometry

Various approaches were evaluated in order to eliminate the spectral interferences noted when Pt and Pd has to be determined in environmental dust samples by ICP-MS. The chemical separation of Pt and Pd from the matrix components on ion-exchange resins was applied. The performance of cation-exchange resins (Dowex 50 WX-8, Dowex 50 WX-2, Dowex HCR-S, Varion KS, Cellex-P) for the separation of interfering ions was then examined. It was found that Dowex 50 WX-8 shows best performance. The effects of mass, mesh number of resin and concentration of Cl⁻ ions on matrix separation were also studied. Another approach was to use the anion-exchange sorbent Cellex-T, which allows almost total retention of both analytes followed by their elution with 0.1 mol L⁻¹ thiourea in 1 mol L⁻¹ HCl. This procedure however can be used only for platinum determination by ICP-MS. The accuracy of proposed procedures was confirmed by the analysis of certified material BCR-723, and then it was used for determination Pt and Pd in samples of road dust.     

Investigation of ICP-MS spectral interferences in the determination of Rh, Pd and Pt in road dust: Assessment of correction algorithms via uncertainty budget analysis and interference alleviation by preliminary acid leaching

A method for classification of the potential spectral interferences in inductively coupled plasma mass spectrometry (ICP-MS) was proposed based on statistical assessment of the interfering signals. The concept was applied to investigate the variety of spectral interferences over the isotopes of Rh, Pd and Pt concerning their analysis in road dust samples. For the significant interferences the applicability of mathematical corrections using two alternative algorithms were studied by uncertainty budget analysis and the approach resulting in lower combined uncertainty of the corrected signals was selected. Further the uncertainty evaluation was used for assessment of the most appropriate Pd isotope to be measured. The adequateness of the mathematical corrections for Rh and Pd was highly relevant to the number of elements causing spectral interferences and the relative analyte/interferent concentrations. This was overcome by preliminary road dust leaching with 0.35 mol l⁻¹ hydrochloric acid. Interferents present as easily soluble salts were substantially removed form the samples while the platinum group metals were not leached which allowed a relative analyte preconcentration to be obtained. For the leached samples the isotopes of Rh and Pd were still spectrally interfered from Sr, Y and Pb but at considerably lesser degree thus after mathematical correction the ICP-MS analysis of Rh, Pd and Pt was reliable and robust using the isotopes 103, 105 and 195, respectively. The method was validated via an alternative analysis based on selective separation of the platinum group metals by microwave-assisted cloud point extraction.     

Electrothermal vaporization inductively coupled plasma atomic emission spectrometry determination of gold, palladium, and platinum using chelating resin YPA(4) as both extractant and chemical modifier

A new method for determination of trace gold (Au), palladium (Pd), and platinum (Pt) in environmental and geological samples by electrothermal vaporization (ETV)-inductively coupled plasma atomic emission spectrometry (ICP-AES) with the use of chelating resin YPA₄ as both solid phase extractant and chemical modifier has been developed. The resin loaded with analytes was prepared to slurry and directly introduced into the graphite furnace without any pretreatment. The factors affecting the vaporization behaviors of Au, Pd, and Pt were investigated in detail. It was found that, in the presence of YPA₄, Au and Pd could be quantitatively vaporized at lower vaporization temperature of 1900 °C. Compared with the conventional electrothermal vaporization, the vaporization temperature was decreased by 700 °C, and the detection limits for Au and Pd was decreased by a three-fold. However, a little effect of YPA₄ on the ETV-ICP-AES determination of Pt was found. Under the optimized conditions, the detection limits (3σ) of Au, Pd, and Pt for this method are 75, 60, and 217 pg, respectively; and their relative standard deviations (R.S.D.) are 4.4, 5.6, and 3.7%, respectively (n=9, C=0.2 μg ml⁻¹). The proposed method has been applied to the determination of trace Pd and Pt in sewage sludge, and the results well agreed with the recommended values. In order to further verify the accuracy of the developed method, a GBW07293 certified geological reference material and an auto catalyst NIST SRM 2557 reference material were analyzed, and the determined values coincided with the certified values very well.     

Determination of platinum, palladium and rhodium in biological and environmental samples by low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry with diethyldithiocarbamate as chemical modifier

A novel method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace amounts of Pt(II), Pd(II) and Rh(III), based on gaseous compounds introduction into the plasma as their diethyldithiocarbamate complexes by electrothermal vaporization (ETV), was developed. At the temperature of 1100 °C, the trace amounts of Pt, Pd and Rh were vaporized into plasma. The factors affecting the formation of the chelates and their vaporization behaviors, such as ashing temperature and time, vaporization temperature and time, pH and the concentration of chelating reagents were studied in detail. Under the optimized conditions, the limits of detection (LODs) (3σ) of Pt, Pd and Rh for tested solutions were 5.4, 1.4 and 0.8 ng ml⁻¹, and for actual sample (auto-catalyst NIST SRM 2557) were 0.27, 0.07 and 0.04 μg g⁻¹, respectively. The relative standard deviations (RSDs) for Pt, Pd and Rh were 1.4, 2.6 and 2.4% (C_Pt=0.5 μg ml⁻¹, C_Pd,Rh=0.25 μg ml⁻¹, n=7), respectively. The linear ranges of calibration graphs for Pt, Pd and Rh cover three orders of magnitude. Compared with conventional electrothermal vaporization technique, using the reagent of diethyldithiocarbamate as chemical modifier could not only enhance the analytical sensitivities, but also reduce the vaporization temperature. By combination with a separation/preconcentration step, the proposed method had been successfully applied to the analysis of the artificial seawater, tap water and urine with recoveries ranging from 91 to 106%. The two certified reference material meager platinpalladium ore GBW 07293 and auto-catalyst NIST SRM 2557 was also analyzed for validation, and the determined values obtained were in good agreement with the certified values.     

Determination of Pd,Rh, Pt,Au in road dust by electrothermal vaporization inductively coupled plasma mass spectrometry with slurry sampling

Inductively coupled plasma mass spectrometry coupled with ultrasonic slurry sampling electrothermal vaporization (USS-ETV-ICP-MS) has been applied to determine Pd, Rh, Pt and Au in 0.5% m/v slurries of several road dust samples. 2% m/v ammonium pyrrolidine dithiocarbamate (APDC) was used as the modifier to enhance the ion count. The influence of instrument operating conditions, slurry preparation and interferences on the ion count was reported. This method has been applied to the determination of Pd, Rh, Pt and Au in BCR 723 Road Dust and NIST SRM 2709 San Joaquin Soil reference materials and two road dust samples collected locally. The analysis results of the standard reference materials agreed with the certified values. Precision between sample replicates was better than 10% for all the determinations. The method detection limits estimated from standard addition curves were 0.9, 0.4, 0.6 and 0.4 ng g⁻¹ for Pd, Rh, Pt and Au, respectively, in original dust samples.     

Problems,possibilities and limitations of inductively coupled plasma atomic emission spectrometry in the determination of platinum,palladium and rhodium in samples with different matrix composition

The economic and geological importance of platinum group of elements has led to the development of analytical methods to quantify them in different types of samples. In the present paper the quantitative information for spectral interference in radial viewing 40.68 MHz inductively coupled plasma atomic emission spectrometry in the determination of Pt, Pd and Rh in the presence of complex matrix, containing Al, Ca, Fe, Mg, Mn, P and Ti as matrix constituents was obtained. The database was used for optimum line selections. By using the selected analysis lines the following detection limits in ng g^− 1 were obtained: Pt 1700, Pd-1440, Rh-900. The reached detection limits determine the possibilities and limitation of the direct ICP-AES method in the determination of Pt, Pd and Rh in geological and environmental materials. The database for spectral interferences in the presence of aluminum can be used for the determination of platinum group of elements in car catalysts.     

Assessment of ion imprinted polymers based on Pd(II) chelate complexes for preconcentration and FAAS determination of palladium

New ion-imprinted polymeric (IIP) materials were synthesized by copolymerization of 4-vinylpyridine (VP) and styrene as functional monomers and divinylbenzene as a cross-linking agent with chelating complexes of Pd(II) in the presence of 2,2-azobisisobutyronitrile as an initiator. The complexes of Pd(II) with ammonium pyrrolidinedithiocarbamate (APDC), N,N′-diethylthiourea (DET), and dimethylglyoxime (DMG) were used for this purpose. Chloroform, ethanol, and cyclohexanol were applied as porogens. The ion-imprinted polymers were tested in a flow mode as sorbents for solid-phase extraction of palladium from aqueous solutions. The conditions of Pd(II) separation on all polymers were optimized. The efficiencies of retention of Pd on different polymers in the presence of high excess of interfering ions were compared. The effect of the used porogen on the analytical performance of the prepared polymers was also investigated. The calculated sorbent capacities for Pd(II) were in the range from 9.25 mg g⁻¹ to 13.3 mg g⁻¹. The sorbent with Pd(II) imprinted as Pd-DMG-VP complex in chloroform was used for preconcentration of trace amounts of Pd. The detection limit for 100 mL of the sample was 5 μg L⁻¹ using flame atomic absorption spectrometry (FAAS). The developed method was applied for the determination of Pd in water samples.     

Multi-elemental characterization of tunnel and road dusts in Houston,Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152 ± 52, 770 ± 208 and 529 ± 130 ng g⁻¹ respectively in tunnel dusts while they varied between 6 and 8 ng g⁻¹, 10 and 88 ng g⁻¹ and 35 and 131 ng g⁻¹ in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand anthropogenic influences on their biogeochemical cycling.     

On the determination of platinum group elements in environmental materials by inductively coupled plasma mass spectrometry and microwave digestion

The interferences from Cd, Cu, Hf, Pb, Sr, Zn, Zr and Y on the inductively coupled plasma quadrupole mass spectrometry (ICP-MS) determination of Pt, Pd, Rh, Ru and Ir in geological (Pt-ore SARM-7, abundance range for platinum metals 0.07-3.74 μg/g) and environmental samples (sediment JSd-2 abundance range for Pt and Pd 0.0167-0.021 μg/g; road dust and plant sample) are evaluated using model solutions, real samples and comparison to inductively coupled plasma atomic emission spectrometry (ICP-AES) results. Pt, Rh, Ru and Ir can be determined usually after introduction of corrections for the interference in all investigated materials though in sediments the direct determination of Pt might be a problem depending on the actual Hf concentrations. The direct determination of Pd (after microwave-assisted acid digestion) is possible in ores using all investigated isotopes (, , ), in plants using and correction for the interferences of Zr, Mo and Cd, and not possible in sediments and road dust. Therefore, we developed a procedure for isolation of Pd using its diethyl-dithio-carabamate (DDTC) complex. The detection limits for Pt, Pd and Ir are 0.015 ng/g, and for Ru and Rh 0.03 ng/g.     

High selectivity for l-cysteine residue at axial solvated site of trigonal-bipyramidal palladium(II) complex with tripodal tetradentate phosphine

The five-coordinate trigonal-bipyramidal palladium(II) and platinum(II) complexes with sulfur-coordinated glutathione at the axial position, [Pd(gluta)(pp₃)](BF₄) and [Pt(gluta)(pp₃)](PF₆) (gluta = glutathionate, pp₃ = tris[2-(diphenylphosphino)ethyl]phosphine), were prepared and characterized by ³¹P NMR spectroscopy. The dimeric square-planar platinum(II) complex [Pt(pp₃)]₂(PF₆)₄ gave the monomeric five-coordinate solvated complex, [Pt(pp₃)(CH₃CN)]²⁺, in acetonitrile. Extraction experiments for amino acids from the aqueous solution to the chloroform layer were carried out by using [Pd(pp₃)(CH₃CN)]²⁺, [Pt(pp₃)(CH₃CN)]²⁺, and [Pd(p₃)(CH₃CN)]²⁺ (p₃ = bis[2-(diphenylphosphino)ethyl]phenylphosphine) as extractants. High selectivity for the thiolate sulfur atom in l-cysteinate was observed at the solvated coordination site in [Pd(pp₃)(CH₃CN)]²⁺. The selectivity was applied to extraction of l-cysteinate from a mixture of some amino acids and, further, the reduced form of glutathionate from a mixture of the reduced and oxidized forms of glutathione.     

Poly(3-methylthiophene)/palladium sub-micro-modified sensor electrode. Part II: Voltammetric and EIS studies, and analysis of catecholamine neurotransmitters, ascorbic acid and acetaminophen

Promising voltammetric sensors based on the modification of Pt and poly(3-methylthiophene) (PMT) electrodes with Pd nanoparticles were achieved for the determination of catecholamine neurotransmitters, ascorbic acid and acetaminophen. Electrochemistry of the indicated compounds was studied at these electrodes and interesting electrocatalytic effects were found. Furthermore, simple, easily prepared one electrochemical step Pd-modified Pt electrode (Pt/Pd) is reported for the first time. Cyclic voltammetry (CV) and chronocoulometry (CC) were used for the determination of the apparent diffusion coefficients in different electrolytes at these electrodes and the values are in the range from 10⁻⁴ to 10⁻⁵ cm² s⁻¹. Furthermore, it was found that the method of polymer formation had a substantial effect on the synergism between the polymer film and the loaded metal particles towards the oxidation of dopamine (DA) in different supporting electrolytes. This was confirmed by the CV, CC and EIS (electrochemical impedance spectroscopy) as well as SEM (Scanning Electron Microscopy) results. Pt and PMT electrodes modified with Pd nanoparticles showed excellent results for the simultaneous determination of tertiary and quaternary mixtures of the studied compounds.     

On-line preconcentration and recovery of palladium from waters using polyaniline (PANI) loaded in mini-column and determination by ICP-MS; elimination of spectral interferences

The applicability of polyaniline (PANI) for the on-line preconcentration and recovery of palladium from various water samples has been investigated. Batch experiments were performed to optimize conditions such as pH and contact time to achieve quantitative separation of Pd spiked at high (μg ml⁻¹) and low levels (ng ml⁻¹). During all the steps of the removal process, it was found that Pd was selectively removed by PANI even in the presence of various ions. Quantitative removal of Pd occured in the entire studied pH range (1-12) and the K_d value was found to be >10⁶. Kinetic studies show that a contact time of <4 min was adequate to reach equilibrium. The retained Pd was subsequently eluted with a mixture of HCl and thiourea, optimized using a factorial experimental design approach. ICP-OES was used for the micro-level determinations of Pd whereas ICP-MS was used for the determination of Pd at sub-ppb levels.Breakthrough curve using column experiments demonstrated that PANI has an excellent ability to accumulate up to ∼120 mg g⁻¹ of Pd from synthetic sample solutions. A preconcentration factor of about 125 was achieved for Pd when 250 ml of water was passed. PANI columns prepared were used up to 10 times in consecutive retention-elution cycles without appreciable deterioration in their performance. The proposed on-line method also has the ability to remove interfering elements Cu and Y for the determination of Pd in waters by ICP-MS. The reported method has been applied successfully for the determination of Pd in ground water, lake water sea-water and waste water samples. The recoveries were found to be >95% in all cases. These studies indicate that PANI has an excellent ability to preconcentrate Pd from various waters making the method very promising for the determination of Pd.     

PdNi- and Pd-coated electrodes prepared by electrodeposition from ionic liquid for nonenzymatic electrochemical determination of ethanol and glucose in alkaline media

Nonenzymatic electrochemical determination of ethanol and glucose was respectively achieved using PdNi- and Pd-coated electrodes prepared by electrodeposition from the novel metal-free ionic liquid (IL); N-butyl-N-methylpyrrolidinium dicyanamide (BMP-DCA). BMP-DCA provided an excellent environment and wide cathodic limit for electrodeposition of metals and alloys because many metal chlorides could dissolve in this IL where the reduction potentials of Pd(II) and Ni(II) indeed overlapped, leading to the convenience of potentiostatic codeposition. In aqueous solutions, the reduction potentials of Pd(II) and Ni(II) are considerably separated. The bimetallic PdNi coatings with atomic ratios of ∼80/20 showed the highest current for ethanol oxidation reaction (EOR). Ethanol was detected by either cyclic voltammetry (CV) or hydrodynamic amperometry (HA). Using CV, the dependence of EOR peak current on concentration was linear from 4.92 to 962 μM with a detection limit of 2.26 μM (σ = 3), and a linearity was observed from 4.92 to 988 μM using HA (detection limit 0.83 μM (σ = 3)). The Pd-coated electrodes prepared by electrodeposition from BMP-DCA showed electrocatalytic activity to glucose oxidation and CV, HA, and square-wave voltammetry (SWV) were employed to determine glucose. SWV showed the best sensitivity and linearity was observed from 2.86 μM to 107 μM, and from 2.99 mM to 10.88 mM with detection limits of 0.78 μM and 25.9 μM (σ = 3), respectively. For glucose detection, the interference produced from ascorbic acid, uric acid, and acetaminophen was significantly suppressed, compared with a regular Pt disk electrode.     

Determination of precious metals in geological samples by continuous powder introduction microwave induced plasma atomic emission spectrometry after preconcentration on activated carbon

A novel method was developed for analysing geological materials for Au, Ag, Pd and Pt by continuous powder introduction microwave induced plasma atomic emission spectrometry (CPI-MIP-AES). The preconcentration of the trace metals on activated carbon (AC) was performed before conducting MIP-AES measurements in order to obtain accurate and precise analytical results. The method proposed is based on the selective sorption of precious metals that are subsequently introduced to the plasma as a dry particulate aerosol consisted of analytes collected on the sorbent. The technical design and operating conditions of the novel sample introduction system based on the fluidized-bed concept has been optimized. The microwave excitation source with integrated rectangular cavity TE₁₀₁ and vertically positioned plasma torch has been used. The signal stability proved to be adequate for sequential mode of measurements due to the vertical plasma configuration as well as the MIP-AES system compatibility with the CPI technique. Calibration was done using home-made standards obtained by sorption of metals of interest from standard solutions on activated carbon. Precision is typically 1-4% relative standard deviation at the 1 μg g⁻¹ level. Under measurement conditions the detection limits for Ag, Au, Pd and Pt were 24, 43, 57 and 550 ng per 1 g of AC, respectively. The proposed procedure was used for Au, Ag, Pd and Pt determination in the platinum ore SARM-7 as well as Au and Ag in the Chinese soil GBW-07405 certified reference materials. The standard addition technique was used and recoveries revealed that the proposed method shows good accuracy and precision.     

Application of Metalfix Chelamine prior to the determination of noble metals by the inductively coupled plasma atomic emission spectrometry

Metalfix Chelamine chelating resins of two different bead sizes (150-300 and 40-80 μm) were examined and compared regarding their application for sorption of Au, Ir, Pd, Pt, Rh and Ru ions from medium of HCl, HNO₃ and mixtures of HCl and HNO₃. The quantitative enrichment of Au, Ir, Pd and Pt was established for the resin of 150-300 μm particle size and for solutions acidified with HCl and HNO₃ (3:1) up to the concentration of 0.50 mol l⁻¹. In the case of Rh and Ru, the uptake of these metals by the resin was lower than 50%. For the elution, solutions of different reagents, i.e. HCl, HNO₃, KCN, KI, KSCN and (NH₂)₂CS, were studied with respect to the complete release of the analytes retained by the resin. In addition, influence of various base metals, i.e. Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, on the retention of the noble metals was investigated. Under the selected conditions for the retention and elution of Au, Ir, Pd and Pt, the analytical performance of the proposed pre-concentration procedure was evaluated and it was applied to the determination of these noble metals in anodic sludge sample.     

Structural and spectroscopic trends in mononuclear arylchalcogenolato-palladium(II) and -platinum(II) complexes: Crystal structures of [M(TeAr)2(dppe)] {M = palladium, platinum; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane}

A series of mononuclear [M(EAr)₂(dppe)] [M = Pd, Pt; E = Se, Te; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane] complexes has been prepared in good yields by the reactions of [MCl₂(dppe)] and corresponding ArE⁻ with a special emphasis on the aryltellurolato palladium and -platinum complexes for which the existing structural information is virtually non-existent. The complexes have crystallized in five isomorphic groups: (1) [Pd(SePh)₂(dppe)] and [Pt(SePh)₂(dppe)], (2) [Pd(TePh)₂(dppe)] and [Pt(TePh)₂(dppe)], (3) [Pd(SeTh)₂(dppe)], (4) [Pt(SeTh)₂(dppe)] and [Pd(TeTh)₂(dppe)], and (5) [Pt(TePh)₂(dppe)]. In addition, solvated [Pd(TePh)₂(dppe)] · CH₃OH and [Pd(TeTh)₂(dppe)] · 1/2CH₂Cl₂ could be isolated and structurally characterized. The metal atom in each complex exhibits an approximate square-planar coordination. The Pd-Se, Pt-Se, Pd-Te, and Pt-Te bonds span a range of 2.4350(7)-2.4828(7) Å, 2.442(1)-2.511(1) Å, 2.5871(7)-2.6704(8) Å, and 2.6053(6)-2.6594(9) Å, respectively, and the respective Pd-P and Pt-P bond distances are 2.265(2)-2.295(2) Å and 2.247(2)-2.270(2) Å. The orientation of the arylchalcogenolato ligands with respect to the M(E₂)(P₂) plane has been found to depend on the E-M-E bond angle. The NMR spectroscopic information indicates the formation of only cis-[M(EAr)₂(dppe)] complexes in solution. The trends in the ³¹P, ⁷⁷Se, ¹²⁵Te, and ¹⁹⁵Pt chemical shifts expectedly depend on the nature of metal, chalcogen, and aryl group. Each trend can be considered independently of other factors. The ⁷⁷Se or ¹²⁵Te resonances appear as second-order multiplets in case of palladium and platinum complexes, respectively. Spectral simulation has yielded all relevant coupling constants.     

Radiochemical neutron activation analysis for determination of Au,Ag, Pt and Pd in geological samples

A procedure for separation of Au, Ag, Pt, and Pd in geological samples has been developed. After irradiation, samples were fused with Na₂O₂ and silver was separated by filtering through a PbCl₂ filter in 4M nitric acid solution. Au, Pt and Pd were concentrated with rhodium and thiourea as rhodium sulfide and the separation process of these elements was carried out by a chromatographic method. Au, Pt and Pd were retained on a Dowex-1×8 anion column in 1M HCl. Pd was eluted from the column by using a mixture of 75% HCl acid-25% acetone. Au was eluted by using a mixture of 10% HCl-90% acetone. In the gold fraction, Pt was also determined through the photopeak of¹⁹⁹Au radionuclide (158 keV). The method was simple and rapid.     

A sensitive amperometric sensor for hydrazine and hydrogen peroxide based on palladium nanoparticles/onion-like mesoporous carbon vesicle

Onion-like mesoporous carbon vesicle (MCV) with multilayer lamellar structure was synthesized by a simply aqueous emulsion co-assembly approach. Palladium (Pd) nanoparticles were deposited on the MCV matrix (Pd/MCV) by chemical reduction of H₂PdCl₄ with NaBH₄ in aqueous media. Pd(X)/MCV (X wt.% indicates the Pd loading amount) nanocomposites with different Pd loading amount were obtained by adjusting the ratio of precursors. The particular structure of the MCV results in efficient mass transport and the onion-like layers of MCV allows for the obtainment of highly dispersed Pd nanoparticles. The introduction of Pd nanoparticles on the MCV matrix facilitates hydrazine oxidation at more negative potential and delivers higher oxidation current in comparison with MCV. A linear range from 2.0 × 10⁻⁸ to 7.1 × 10⁻⁵ M and a low detection limit of 14.9 nM for hydrazine are obtained at Pd(25)/MCV nanocomposite modified glassy carbon (GC) electrode. A nonenzymatic amperometric sensor for hydrogen peroxide based on the Pd(25)/MCV nanocomposite modified GC electrode is also developed. Compared with MCV modified GC electrode, the Pd(25)/MCV nanocomposite modified GC electrode displays enhanced amperometric responses towards hydrogen peroxide and gives a linear range from 1.0 × 10⁻⁷ to 6.1 × 10⁻³ M. The Pd(25)/MCV nanocomposite modified GC electrode achieves 95% of the steady-current for hydrogen peroxide within 1 s. The combination of the unique properties of Pd nanoparticles and the porous mesostructure of MCV matrix guarantees the improved analytical performance for hydrazine and hydrogen peroxide.