Synthesis of coin-like hollow carbon and performance as Pd catalyst support for methanol electrooxidation

The coin-like hollow carbon (CHC) has been synthesized by only using ethanol as the carbon source with a novel Mg/NiCl₂ catalytic system via a facile solvothermal method for the first time. The CHC synthesized at optimized conditions shows an average thickness of less than 154 nm and the coin diameter of 1–3 μm. The CHC is characterized by SEM, TEM, XRD and electrochemical techniques. Pd on CHC (denotes as Pd/CHC) electrocatalysts are prepared for methanol oxidation in alkaline media. The Pd/CHC electrocatalyst gives a mass activity of 2930 A g⁻¹ Pd for methanol oxidation against 870 A g⁻¹ Pd on Pd/C electrocatalyst. One main reason for the higher mass activity of the Pd/CHC is the higher electrochemical active surface area (EASA) of the Pd/CHC.     

Column solid phase extraction and determination of ultra-trace Au,Pd and Pt in environmental and geological samples

A new sorbent based on cysteine modified silica gel (SiG-cys) was prepared and studied for preconcentration and separation of noble metals Au(III), Pd(II), Pt(II), Pt(IV). Its extraction efficiency was examined by batch and column solid phase extraction procedures. Laboratory experiments performed showed that sorbent is characterized with high selectivity, permiting quantitative sorption (93–97%) of noble metals Au, Pd and Pt from acidic media 0.1–2 mol L^? 1 HCl and unsignificant sorption (less than 2%) for common base metals like Cu, Fe, Mn and Zn. The analytes retained on the sorbent are effectively eluted with 0.1 mol L^? 1 thiourea in 0.1 mol L^? 1 HCl and measured by ETAAS or ICP OES under optimal instrumental parameters. The sorbent showed high mechanical and chemical stability and extraction efficiency was not changed after 500 cycles of sorption/desorption. The sorbent was successfully applied in analyticals procedures for preconcentration and determination of Au, Pd and Pt in geological and soil samples. Detection limits (3σ criteria) achieved, depending on the instrumental methods used are: ETAAS (0.005 μg L^? 1 for Au in river and sea water, 0.002 μg g^? 1 for Au in copper ore and copper concentrate); ICP OES (0.03 μg L^? 1 for Pd and 0.06 μg L^? 1 for Pt in river and sea water, 0.006 μg g^? 1 for Pd in copper ore and copper concentrate and 0.002 μg g^? 1 for soluble Pt in soil). The accuracy of the procedures developed was confirmed by added/found method for sea and river water; by the analysis of national certified materials (copper ore and copper concentrate for Au and Pd) and by determination of the sum of soluble Pt(II) + Pt(IV) in spiked soil samples.     

Minimization of mass interferences in quadrupole inductively coupled plasma mass spectrometric (ICP-MS) determination of palladium using a flow injection on-line displacement solid-phase extraction protocol

A flow injection on-line displacement solid-phase extraction protocol was employed to minimize mass interferences with determination of palladium by inductively coupled plasma mass spectrometry (ICP-MS). The developed method involved in on-line complexing of Ag⁺ with pyrrolidine dithiocarbamate (PDC), presorption of the resultant Ag–PDC onto a microcolumn packed with the cigarette filter, displacement sorption of Pd²⁺ through loading the sample solution onto the microcolumn due to on-line displacement reaction between Pd²⁺ and the presorbed Ag–PDC, elution of the retained Pd²⁺ with 50 μL of ethanol for on-line ICP-MS detection. Interferences from co-existing heavy metal ions with lower stability of their PDC complexes relative to Ag–PDC were minimized/eliminated. No interferences from 5 mg L^− 1 Zn and 3 mg L^− 1 Pb for ¹⁰⁴Pd, 0.4 mg L^− 1 Cu for ¹⁰⁵Pd, 6 mg L^− 1 Zn and 2 mg L^− 1 Cd for ¹⁰⁶Pd, 6 mg L^− 1 Zn and 3 mg L^− 1 Cd for ¹⁰⁸Pd, and 2 mg L^− 1 Cd for ¹¹⁰Pd were observed for the determination of 100 ng L^− 1 Pd. The enhancement factors of 71–75, sample throughput of 23 samples h^− 1 and detection limits of 2.8–3.5 ng L^− 1 were achieved with the consumption of 3.0 mL of sample solution. The precision (RSD) for eleven replicate determinations of Pd at the 100 ng L^− 1 level was 1.8–2.7%. The developed method was applied to the determination of palladium in rock samples.     

Cu determination in crude oil distillation products by atomic absorption and inductively coupled plasma mass spectrometry after analyte transfer to aqueous solution

Cu was determined in a wide range of petroleum products from crude oil distillation using flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Different procedures of sample preparation were evaluated: (i) mineralization with sulfuric acid in an open system, (ii) mineralization in a closed microwave system, (iii) combustion in hydrogen–oxygen flame in the Wickbold's apparatus, (iv) matrix evaporation followed by acid dissolution, and (v) acidic extraction. All the above procedures led to the transfer of the analyte into an aqueous solution for the analytical measurement step. It was found that application of FAAS was limited to the analysis of the heaviest petroleum products of high Cu content. In ICP-MS, the use of internal reference method (with Rh or In as internal reference element) was required to eliminate the matrix effects in the analysis of extracts and the concentrated solutions of mineralized heavy petroleum products. The detection limits (in original samples) were equal to, respectively, 10, 86, 3.3, 0.9 and 0.4 ng g^− 1 in procedures i–v with ETAAS detection and 10, 78, 1.1 and 0.5 ng g^− 1 in procedures i–iii and v with ICP-MS detection. The procedures recommended here were validated by recovery experiments, certified reference materials analysis and comparison of results, obtained for a given sample, in different ways. The Cu content in the analyzed samples was: 50–110 ng g^− 1 in crude oil, < 0.4–6 ng g^− 1 in gasoline, < 0.5–2 ng g^− 1 in atmospheric oil, < 6–100 ng g^− 1 in heavy vacuum oil and 140–300 ng g^− 1 in distillation residue.     

Evaluation of tungsten–rhodium coating on an integrated platform as a permanent chemical modifier for cadmium,lead, and selenium determination by electrothermal atomic absorption spectrometry

A tungsten–rhodium coating on the integrated platform of a transversely heated graphite atomizer is proposed as a permanent chemical modifier for the determination of Cd, Pb, and Se by electrothermal atomic absorption spectrometry. It was demonstrated that coating with 250 μg W+200 μg Rh is as efficient as the conventional Mg(NO₃)₂+NH₄H₂PO₄ or Pd+Mg(NO₃)₂ modifiers for avoiding most serious interferences. The permanent W–Rh modifier remains stable for 300–350 firings of the furnace, and increases tube lifetime by 50%–100% when compared to pyrolytic carbon integrated platforms. Also, there is less degradation of sensitivity during the atomizer lifetime when compared with the conventional modifiers, resulting in a decreased need of re-calibration during routine analysis. The characteristic masses and detection limits achieved using the permanent modifier were respectively: Cd 1.1±0.4 pg and 0.020 μgL⁻¹; Pb 30±3 pg and 0.58 μgL⁻¹ and Se 42±5 pg and 0.64μgL⁻¹. Results from the determination of these elements in water reference materials were in agreement with the certified values, since no statistical differences were found by the paired t-test at the 95% level.     

Determination of traces of Sb(III) using ASV in Sb-rich water samples affected by mining

Chemical speciation [Sb(V) and Sb(III)] affects the mobility, bioavailability and toxicity of antimony. In oxygenated environments Sb(V) dominates whereas thermodynamically unstable Sb(III) may occur. In this study, a simple method for the determination of Sb(III) in non acidic, oxygenated water contaminated with antimony is proposed. The determination of Sb(III) was performed by anodic stripping voltammetry (ASV, 1–20 μg L⁻¹ working range), the total antimony, Sb(tot), was determined either by inductively coupled plasma mass spectrometry (ICP-MS, 1–100 μg L⁻¹ working range) or inductively coupled plasma optical emission spectrometry (ICP-OES, 100–10,000 μg L⁻¹ working range) depending on concentration. Water samples were filtered on site through 0.45 μm pore size filters. The aliquot for determination of Sb(tot) was acidified with 1% (v/v) HNO₃. Different preservatives, namely HCl, L(+) ascorbic acid or L(+) tartaric acid plus HNO₃, were used to assess the stability of Sb(III) in synthetic solutions.The method was tested on groundwater and surface water draining the abandoned mine of Su Suergiu (Sardinia, Italy), an area heavily contaminated with Sb. The waters interacting with Sb-rich mining residues were non acidic, oxygenated, and showed extreme concentrations of Sb(tot) (up to 13,000 μg L⁻¹), with Sb(III) <10% of total antimony. The stabilization with L(+) tartaric acid plus HNO₃ appears useful for the determination of Sb(III) in oxygenated, Sb-rich waters. Due to the instability of Sb(III), analyses should be carried out within 7 days upon the water collection. The main advantage of the proposed method is that it does not require time-consuming preparation steps prior to analysis of Sb(III).     

Determination of mercury in organic solvents and gas condensates by μflow-injection — inductively coupled plasma mass spectrometry using a modified total consumption micronebulizer fitted with single pass spray chamber

A high-throughput flow-injection — inductively coupled plasma mass spectrometry (ICP MS) analytical method was developed for the determination of mercury in gas condensates and carbon-rich solvents. The sample (undiluted or diluted 10-fold) was introduced via a modified total consumption micronebulizer working at a flow rate of 30 μl min^− 1 and fitted with a singlepass spray chamber. This low flow rate and the addition of oxygen (70 ml min^− 1) assured the plasma stability and reduced the carbon build-up on the interface and on ion lenses. A limit of detection of 0.5 ng g^− 1 (2.5 μl sample) was obtained owing to the reduction of dead volume and sample dispersion (peak-width was 3 s at half-height) in the liquid pass of the nebulizer. The elimination of the memory effect reduced the washout time down to 30 s which resulted in a throughput of ca. 60 h^− 1. The method was validated by the analysis of 3 gas condensates by cold vapour atomic absorption spectrometry.     

Study of the chemical composition of particulate matter from the Rio de Janeiro metropolitan region,Brazil, by inductively coupled plasma-mass spectrometry and optical emission spectrometry

Air quality in the metropolitan region of Rio de Janeiro was evaluated by analysis of particulate matter (PM) in industrial (Santa Cruz) and rural (Seropédica) areas. Total suspended particles (TSP) and fine particulate matter (PM_2.5) collected in filters over 24 h were quantified and their chemical composition determined. TSP exceeded Brazilian guidelines (80 μg m^− 3) in Santa Cruz, while PM_2.5 levels exceeded the World Health Organization guidelines (10 μg m^− 3) in both locations. Filters were extracted with water and/or HNO₃, and the concentrations of 20 elements, mostly metals, were determined by inductively coupled plasma mass spectrometry (ICP-MS) and optical emission spectrometry (ICP OES). Water soluble inorganic anions were determined by ion chromatography (IC). To estimate the proportion of these elements extracted, a certified reference material (NIST SRM 1648a, Urban Dust) was subjected to the same extraction process. Concordant results were obtained by ICP-MS and ICP OES for most elements. Some elements could not be quantified by both techniques; the most appropriate technique was chosen in each case. The urban dust was also analyzed by the United States Environmental Protection Agency (US EPA) method, which employs a combination of hydrochloric and nitric acids for the extraction, but higher extraction efficiency was obtained when only nitric acid was employed. The US EPA method gave better results only for Sb. In the PM samples, the elements found in the highest average concentrations by ICP were Zn and Al (3–6 μg m^− 3). The anions found in the highest average concentrations were SO₄^2 − in PM_2.5 (2–4 μg m^− 3) and Cl⁻ in TSP (2–6 μg m^− 3). Principal component analysis (PCA) in combination with enrichment factors (EF) indicated industrial sources in PM_2.5. Analysis of TSP suggested both anthropogenic and natural sources. In conclusion, this work contributes data on air quality, as well as a method for the analysis of PM samples by ICP-MS.     

Laser ablation–inductively coupled plasma–dynamic reaction cell–mass spectrometry for the multi-element analysis of polymers

In this work, the potential of laser ablation–inductively coupled plasma–mass spectrometry for the fast analysis of polymers has been explored. Different real-life samples (polyethylene shopping bags, an acrylonitrile butadiene styrene material and various plastic bricks) as well as several reference materials (VDA 001 to 004, Cd in polyethylene) have been selected for the study. Two polyethylene reference materials (ERM-EC 680 and 681), for which a reference or indicative value for the most relevant metals is available, have proved their suitability as standards for calibration.Special attention has been paid to the difficulties expected for the determination of Cr at the μg g^− 1 level in this kind of materials, due to the interference of ArC⁺ ions on the most abundant isotopes of Cr. The use of ammonia as a reaction gas in a dynamic reaction cell is shown to alleviate this problem, resulting in a limit of detection of 0.15 μg g^− 1 for this element, while limiting only modestly the possibilities of the technique for simultaneous multi-element analysis. In this regard, As is the analyte most seriously affected by the use of ammonia, and its determination has to be carried out in vented mode, at the expense of measuring time.In all cases studied, accurate results could be obtained for elements ranging in content from the sub-μg g^− 1 level to tens of thousands of μg g^− 1. However, the use of an element of known concentration as internal standard may be needed for materials with a matrix significantly different from that of the standard (polyethylene in this work).Precision ranged between 5% and 10% RSD for elements found at the 10 μg g^− 1 level or higher, while this value could deteriorate to 20% for analytes found at the sub-μg g^− 1 level. Overall, the technique evaluated presents many advantages for the fast and accurate multi-element analysis of these materials, avoiding laborious digestion procedures and minimizing the risk of analyte losses due to the formation of volatile compounds.     

Evaluation of four sample treatments for determination of platinum in automotive catalytic converters by graphite furnace atomic absorption spectrometry

Conventional and microwave assisted digestion, both using aqua regia, alkaline fusion with lithium metaborate and aqueous slurries were evaluated as sample treatments for determination of Pt in automotive catalytic converters by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). Determination of platinum by GF-AAS in samples of the catalytic converter's substrates, prepared by the four methods described, indicates that the highest platinum concentration i.e. maximum Pt extraction in the range of 748 ± 15–998 ± 10 μg mL^− 1, is obtained for samples dissolved by alkaline fusion, closely followed by analysis of aqueous plus Triton X-100 slurries 708 ± 14–958 ± 10 μg mL^− 1, while neither one of the acid digestion procedures achieved total dissolution of the samples. Slurry analysis is thus shown to be a viable alternative and is recommended, based on its speed and ease of implementation. Aqueous standards calibration curves and the standard addition methods were also compared. The results showed that no appreciable matrix effects are present, regardless of the sample preparation procedure used. Precision of the measurements, expressed as percentage relative standard deviation, ranged between 2.5 to 4.9%. Accuracy of the results was assessed by recovery tests which rendered values between 98.9 and 100.9%.     

Copper film electrode for anodic stripping voltammetric determination of trace mercury and lead

A novel in-situ prepared copper film electrode (CuFE) for anodic stripping voltammetric measurement of trace levels of Hg(II) and Pb(II) is presented. The optimal electroanalytical performance of the CuFE was achieved in electrolyte solution comprising 0.1 M HCl and 0.4 M NaCl. The CuFE exhibited excellent operation in the presence of dissolved oxygen with calculated LoD of 0.1 μg L^− 1 Hg(II) and 0.06 μg L^− 1 Pb(II) in combination with 300 s accumulation time, repeatability with RSD of 4.5% for Hg(II) and 0.9% for Pb(II) (n = 12), and favourable linear response in the examined concentration range of 10–100 μg L^− 1 (R² = 0.997) for Hg and 5–70 μg L^− 1 (R² = 0.999) for Pb after 120 s accumulation. The electrode enabled also simultaneous detection of both investigated metal ions and revealed promising electroanalytical characteristics similar to or in certain cases surpassing those of commonly used gold electrodes.     

Direct determination of trace rare earth elements in ancient porcelain samples with slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

A method for the direct determination of trace rare earth elements in ancient porcelain samples by slurry sampling fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry was developed with the use of polytetrafluoroethylene as fluorinating reagent. It was found that Si, as a main matrix element in ancient porcelain sample, could be mostly removed at the ashing temperature of 1200 °C without considerable losses of the analytes. However, the chemical composition of ancient porcelain sample is very complicated, which makes the influences resulting from other matrix elements not be ignored. Therefore, the matrix effect of ancient porcelain sample was also investigated, and it was found that the matrix effect is obvious when the matrix concentration was larger than 0.8 g l^− 1. The study results of particle size effect indicated that when the sample particle size was less than 0.057 mm, the particle size effect is negligible. Under the optimized operation conditions, the detection limits for rare earth elements by fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry were 0.7 ng g^− 1 (Eu)–33.3 ng g^− 1(Nd) with the precisions of 4.1% (Yb)–10% (La) (c = 1 μg l^− 1, n = 9). The proposed method was used to directly determine the trace rare earth elements in ancient porcelain samples produced in different dynasty (Sui, Ming and Qing), and the analytical results are satisfactory.     

Development of a solid phase extraction method for the multielement determination of trace metals in natural waters including sea-water by FI-ICP-MS

An automated solid phase extraction method by flow analysis on-line inductively coupled plasma mass spectrometry (FI-ICP-MS) for the determination of cobalt, chromium, nickel, cadmium, manganese, zinc, copper and lead in sea-water and other natural waters is described. The system is based on retention of the analytes onto a minicolumn packed with a chelating resin, 1,5-bis (2-pyridyl)-3-sulphophenyl methylene thiocarbonohydrazide immobilized on aminopropyl-controlled pore glass, placed in the injection valve of a simple flow manifold. The effects of chemical and flow variables were investigated and selected as a compromise between sensitivity and sampling frequency. So, the sample solutions (adjusted to pH 8.0 ± 0.5) were passed through the column. After washing the column with water, the adsorbed metals were subsequently eluted into the plasma with 4% m/m nitric acid. Detection limits of the trace metals (180 s sample loading time at a sample flow rate of 0.7 mL min^? 1; sampling frequency 8.6 h^? 1) were 0.002 μg L^? 1 for Co, 0.057 μg L^? 1 for Cr, 0.117 μg L^? 1 for Ni, 0.004 μg L^? 1 for Cd, 0.210 μg L^? 1 for Mn, 0.260 μg L^? 1 for Zn, 0.030 μg L^? 1 for Cu and 0.020 μg L^? 1 for Pb, with enrichment factors between 2.2 and 6.8. The accuracy of the proposed method was checked with certified reference materials (CRMs) of sea-water SLEW 3, LGC6016 and CASS-5, river water SLRS-5 and fortified lake water TMDA-54.4. The results from the determination of these metals were in agreement with the certified values and recovery values ranged between 92.2 and 110.6%. The method was applied to the determination of these metal ions in sea-water samples collected in the Málaga Bay in order to realize a pilot study necessary to generate preliminary information on which to base a more detailed pollution study by heavy metals of the Bay.     

Determination of zinc and copper in human hair by slurry sampling employing sequential multi-element flame atomic absorption spectrometry

The present work proposes a direct method based on slurry sampling for the determination of zinc and copper in human hair samples by multi-element sequential flame atomic absorption spectrometry. The slurries were prepared by cryogenic grinding and sonication of the samples. The optimization step was performed using univariate methodology and the factors studied were: nature and concentration of the acid solution, amount sample/slurry volume, sonication time, and particle size. The established experimental conditions are the use of a sample mass of 50 mg, 2 mol L^− 1 nitric acid solution, sonication time of 20 min and slurry volume of 10 mL. Adopting the optimized conditions, this method allows the determination of zinc and copper with detection limits of 88.3 and 53.3 ng g^− 1, respectively, and precision expressed as relative standard deviation (RSD) of 1.7% and 1.6% (both, n = 10) for contents of zinc and copper of 100.0 and 33.3 μg g^− 1, respectively. The accuracy was checked and confirmed by analysis of two certified reference materials of human hair. The procedure was applied for the determination of zinc and copper in two human hair samples. The zinc and copper contents varied from 100.0 to 175.6 and from 3.2 to 32.8 μg g^− 1, respectively. These samples were also analyzed after complete digestion in a closed system and determination by FAAS. The statistical comparison by t-test (95% confidence level) showed no significant difference between these results.     

Direct determination of bromine in plastic materials by means of solid sampling high-resolution continuum source graphite furnace molecular absorption spectrometry

This work investigates the potential of high-resolution continuum source graphite furnace molecular absorption spectrometry for the direct determination of bromine in polymers, which could be interesting in view of the current regulations restricting the use of organobrominated compounds. The method developed is based on the addition of Ca (300 μg) and Pd (30 μg) to favor the formation of CaBr, which is monitored at the main molecular “lines” (rotational spectra) found in the vicinity of 625.315 nm.It was found that accurate results could be obtained for all the samples investigated (polyethylene, polypropylene and acrylonitrile butadiene styrene certified reference materials) using any of the lines studied and constructing the calibration curve with aqueous standards. Furthermore, the combined use of the main four CaBr lines available in the spectral area simultaneously monitored permits to easily expand the linear range up to 2000 ng, provides a limit of detection of 1.8 ng (1.8 μg g^− 1 for a mass of 1 mg) and further improves precision to values between 3–7% RSD. Overall, the method proposed seems suited for the fast and simple control of these types of samples (approximately 10 min for sample are required), circumventing the traditional problems associated with sample digestion (e.g., losses of volatile compounds), and providing sufficient sensitivity to easily comply with regulations.     

Comparison of performances of bioanodes modified with graphene oxide and graphene–platinum hybrid nanoparticles

The performances of graphene oxide (GO) and graphene–platinum hybrid nanoparticles (Gr-Pt hybrid NPs) were compared for biofuel cell (BFC) systems. This is the first study that constitutes these nanomaterials in BFC systems. For this purpose, fabricated bioanodes were combined with laccase modified biocathode in a single cell membraneless BFC. Power and current densities of these systems were calculated as 2.40 μW cm^− 2 and 211.90 μA cm^− 2 for GO based BFC and 4.88 μW cm^− 2 and 246.82 μA cm^− 2, for Gr-Pt hybrid NPs based BFC. As a result, a pioneer study which demonstrates the effective performances of combination of graphene with Pt was conducted.     

Studying the oxygen reduction and hydrogen oxidation reactions under realistic fuel cell conditions

A new approach to test fuel cell catalysts under conditions of high mass transport and variable temperature is described. This approach relies upon utilising a 5 μm thick gold grid to act as a catalyst support in contact with a perfluorsulfonic acid (PFSA) membrane in a true three electrode electrochemical configuration. The gold grid has 20 μm × 20 μm sized holes in it which allow the reactant gas to reach the catalyst layer. The high electrical conductivity and low profile of the grid ensure that electrical and mass transport losses are minimal. We have used this configuration to look at the oxygen reduction reaction (orr) and the hydrogen oxidation reaction (hor) on a platinum-black and platinum on carbon catalyst at a loading of about 10 μg cm⁻². We find that for the orr we can measure kinetic currents over the entire range of relevant fuel cell operating potentials (0.55–1 V). Although platinum-black shows higher specific catalytic activity towards the orr than platinum on carbon at high potentials, this performance benefit is reduced at lower potentials. For the hor we measure exchange current densities of 0.022 A cm⁻² and 0.026 A cm⁻² respectively on the Pt-Black and Pt/C. These values indicate that there does not appear to be a size effect for the hor, unlike the orr.     

Determination of Exemestane in bulk and pharmaceutical dosage form by HPTLC

An HPTLC method for analysis of Exemestane in bulk and pharmaceutical formulation has been established and validated. The analyte was separated on aluminium plates precoated with silica gel 60 F₂₅₄. The mobile phase was chloroform:methanol 9.2:0.8 (v/v). Quantification was done by densitometric scanning at 247 nm. Response was a linear function of Exemestane concentration in the range of 100–500 μg mL⁻¹. The limit of detection and quantification for Exemestane were 5.8 and 17.58 μg mL⁻¹, respectively. Average recovery of Exemestane was 100.1, which shows that the method was free from interference from excipients present in the formulation. The established method enabled accurate, precise, and rapid analysis of Exemestane in bulk as well as pharmaceutical formulation.     

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N₂ adsorption–desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L^?1 HCl–3% thiourea solution at a flow rate of 2.0 mL min^?1. The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g^?1 for Pd(II).The detection limit (3σ) of the method was 0.29 ng mL^?1, and the relative standard deviation (RSD) was 3.1% (n = 11). The method was validated using certified reference material, and has been applied for the determination of trace Pd(II) in actual samples with satisfactory results.     

Electrothermal vaporization coupled with inductively coupled plasma array–detector mass spectrometry for the multielement analysis of Al2O3 ceramic powders

An electrothermal vaporization (ETV) system useful for the analysis of solutions and slurries has been coupled with a sector-field inductively coupled plasma mass spectrometer (ICP–MS) equipped with an array detector. The ability of this instrument to record the transient signals produced for a number of analytes in ETV–ICP–MS is demonstrated. Detection limits for Mn, Fe, Co, Ni, Cu, Zn and Ga are in the range of 4–60 pg μL^− 1 for aqueous solutions and in the low μg g^− 1 range for the analysis of 10 mg mL^− 1 slurries of Al₂O₃ powders. The dynamic ranges measured for Fe, Cu and Ga spanned 3–5 orders of magnitude when the detector was operated in the low-gain mode and appear to be limited by the ETV system. Trace amounts of Fe, Cu and Ga could be directly determined in Al₂O₃ powders at the 2–270 μg g^− 1 level without the use of thermochemical reagents. The results well agree with literature values for Fe and Cu, whereas deviations of 50% at the 90 μg g^− 1 level for Ga were found.