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[en] Complete text of publication follows. The use of mathematical correction equations, cool plasma, and dynamic reaction cells is frequent for correcting polyatomic interferences in ICP-MS. For carbon-rich matrixes, the 40Ar12C+ polyatomic ion affects the accuracy of Cr determination based on its main isotope. The aim of this work was to evaluate the employment of an ICP-MS equipped with a collision-reaction interface (CRI, Varian 820-MS) for carbon interference correction on Cr determination at m/z 52. The CRI allowed gas introduction directly into the plasma expansion zone, through modified sampler and skimmer cones, and H2 was tested as collisional and reactional gas. The gas flow-rate, point of introduction and plasma operational settings were systematically evaluated to achieve the lowest detection limits and robust method conditions. Based on typical residual carbon content in acid digestates, solutions containing from 0.1 to 2.0 % m v-1 carbon were prepared to evaluate carbon effect on Cr determination. Oxalic acid was used as carbon source. Preliminary results showed that H2 introduction through the skimmer, kept at 80 mL min-1 flow rate, presented better efficiency than through the sampler because lower BEC values (background equivalent concentration) were obtained. At flow rates lower than 60 mL min-1, Cr recovery value was around 170 % (2.0 % w v-1 carbon) due to the positive interference caused by 40Ar12C+. Using a H2 flow rate of 80 mL min-1, accurate recoveries for 5.0 μg L-1 Cr were achieved. The BEC obtained when using the CRI was ten fold lower than that obtained without using it. The effect of different RF powers (0.60-1.50 kW) and nebulizer flow-rates (0.90-1.10 L min-1) on sensitivity was also studied. The BEC and SBR values were similar for all tested RF powers. The analytical signal was improved using higher flow-rate. However, in order to obtain a low CeO+/Ce+ ratio for plasma (< 3%), plasma was operated at 1.50 kW and 0.90 L min-1. The CRI was fundamental to eliminate carbon effects, and its performance was improved by using robust operation conditions. The authors kindly acknowledge the financial support from the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, Grant 2006/59083-9), CNPq and CAPES.
[en] Full text: First results of a new research project on chemical nanoparticle characterization are presented. Monodisperse micro-droplets of known analyte concentrations are used for calibration since monodisperse standard reference particles are not available. The droplets are injected directly or after prior desolvation into the ICP. Atomization and ionization of analytes are studied spectroscopically by end-on ICPOES, and criteria for complete atomization of particles are given. Our first results already allow estimates on the applicability and some limitations of the method. (author)
[en] This work presents a new chemo sensor Labetalol (LBT) hydrochloride 5 -[1-hydroxy-2-(1-methyl-3-phenylpropylamino)ethyl] salicylamide hydrochloride (LBT) was applied for spectrophotometric determination of UO22+ in aqueous solution. The chemo sensor LBT react with UO22+ forming a new complex UO22+ /LBT at wavelength of 314 nm. The absorbance of the linear calibration curve increases by in creasing UO22 + concentration at linear range of (1.0 – 16.1) × 10-6 mol L-1 with a correlation coefficient (R2= 0.998). The experimental conditions affecting the absorbance development were studied and optimized. The complexes stoichiometry was measured a the absorbance spectra 314 nm and the results were found to be 1:1 (metal: ligand) ratio. The present chemo sensor LBT was effectively validated with respect to linearity, precision, accuracy, detection and quantification limits. For more accurate analysis, the apparent molar absorptivity, Beer’s law, Ringbom and Sandell’s sensitivity have been studied. The results of analysis were statistically compared with those obtained by ICP -OES as a reference method show that, the Student’s t-and F-values at 95% confidence level are less than the theoretical values, which confirmed that there is no significant difference between the chemo sensor LBT and the reference method in the same studied conditions. The chemo sensor LBT provide a simple, sensitive and inexpensive spectrophotometric determination without any complicated equipment. It was also successfully applied for the direct determination of UO22+ in different aqueous samples with satisfactory results
[en] A pneumatically-driven, high efficiency nebulizer is explored for helium inductively coupled plasma mass spectrometry. The aerosol characteristics and analyte transport efficiencies of the high efficiency nebulizer for nebulization with helium are measured and compared to the results obtained with argon. Analytical performance indices of the helium inductively coupled plasma mass spectrometry are evaluated in terms of detection limits and precision. The helium inductively coupled plasma mass spectrometry detection limits obtained with the high efficiency nebulizer at 200 μL/min are higher than those achieved with the ultrasonic nebulizer consuming 2 mL/min solution, however, precision is generally better with high efficiency nebulizer (1-4% vs. 3-8% with ultrasonic nebulizer). Detection limits with the high efficiency nebulizer at 200 μL/min solution uptake rate approach those using ultrasonic nebulizer upon efficient desolvation with a heated spray chamber followed by a Peltier-cooled multipass condenser
[en] Complete text of publication follows. Quantification methods in biological and biomedical applications are a topical research theme. However, accurate determinations of bio-molecules in real-life biological samples represent one of the greatest challenges. MS based approaches often follow the strategy to quantify relative changes, e.g. the relative change in protein amount observed between two biologically different states. ICP-MS is the unrivalled detector for quantification of elemental traces and has been propagated as the method of choice for accurate absolute quantification in biological samples. Quantification via hetero-elements or elemental labelling of the investigated bio-molecules was suggested. This work deals with the evaluation of measurement uncertainty of elemental speciation analysis in the case of bio-analytical applications relying on extraction protocols (e.g. selenium speciation analysis in yeast, speciation studies addressing species metabolism in cell models). Absolute quantification will be critically discussed with regard to sample preparation and ICP-MS detection.
[en] In this study, the mineral composition of a pate made with red deer meat (maral meat), beans and a protein enriching additive was determined. To do so, three formulations of the pate (with different meat, additive and bean ratios) were produced. For each formulation, the content of mineral elements was then determined using inductively coupled plasma mass-spectrometry (ICP-MS). Increased level of minerals, such as K, P, Na, Ca and Mg were obtained in formulations where the additive and the beans were added. The addition of beans significantly increased Ca and P content. The mineral content of the overall better balanced formulation of the maral meat pate was compared to that of other pates. (author)
[en] This short course includes information on these topics and subtopics: (I) Nuclear Properties: (A) Historic roots; (B) Nomenclature; (C) Nuclear Stability and abundance; (D) Uses of isotopic techniques; (II) Instrumentation: (A) Sources; (B) Mass resolving elements; (C) Detectors; (III) Making Isotopic Measurements by ICP-MS: (A) Deadtime Correction; (B) Mass Discrimination; (C) Signal /Noise considerations; (IV) Applications and examples: (A) Isotope dilution; (B) Double Spike; (C) Biological Application; (D) Environmental Application; (E) Geological
[en] This paper describes the development of a very simple micro-flow pneumatic ICP-MS nebulizing solution based on a commercial glass concentric slurry nebuliser and a fused-silica capillary. It appears as a well-performing, low cost system able to nebulize efficiently at a low liquid flow rate (40 000 cps for a 1 ppb 238U solution at 1 μLmin-1). Experimentally, it provides a practical set-up for studying the influence of not only operating conditions (liquid and gas flow rates, temperature) but also nebuliser design (nozzle configuration, capillary tip shape, capillary inner diameter). More precisely it allows the study of liquid-capillary-tip to gas-exit stick-out, i.e. recessed position (e ≤ 0), coplanar liquid and gas exits (e = 0) or liquid protruding configuration (e ≥ 0) in combination with various liquid capillary inner diameters or tip shapes. This investigation brings out several practical results even if the relation between the primary aerosol characteristics (studied by three complementary techniques (PIV, shadowgraphy and ILIDS)) and the ICP-MS signal measured on a tertiary aerosol is not easy to establish precisely. These results are systematically compared to the literature data, replacing them in a more global perspective. It highlights the prime importance of the nozzle configuration i. e. stick-out and liquid capillary inner diameter. The stick-out (e) parameter is of crucial importance both for the primary spray homogeneity in terms of droplet velocity distribution and for tertiary signal intensity and stability but shows no influence on the oxide ratio or on the droplet size distribution. This last characteristic may not be the most relevant criterion for low liquid uptake nebulizers, contrary to millilitre flow-rate ones. The authors hypothesize that this may be linked to the evaporation capacity of the nebulising gas largely exceeding the liquid uptake, creating a fundamentally different situation for the two types of nebulizers. This study also displays the interest of using a flat-end capillary instead of a tapered end which is the solution most commonly employed, and it highlights the existence of an optimum nozzle configuration (e ≥ 0) in terms of sensitivity and stability, that is dependent on the capillary inner diameter. (authors)
[en] Current methods used in document examinations are not suitable to associate or discriminate between sources of paper and gel inks with a high degree of certainty. Nearly non-destructive, laser-based methods using laser induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to improve the forensic comparisons of gel inks, ballpoint inks and document papers based on similarities in elemental composition. Some of the advantages of these laser-based methods include minimum sample consumption/destruction, high sensitivity, high selectivity and excellent discrimination between samples from different origins. Figures of merit are reported including limits of detection, precision, homogeneity at a micro-scale and linear dynamic range. The variation of the elemental composition in paper was studied within a single sheet, between pages from the same ream, between papers produced by the same plant at different time intervals and between seventeen paper sources produced by ten different plants. The results show that elemental analysis of paper by LIBS and LA-ICP-MS provides excellent discrimination (> 98%) between different sources. Batches manufactured at weekly and monthly intervals in the same mill were also differentiated. The ink of more than 200 black pens was analyzed to determine the variation of the chemical composition of the ink within a single pen, between pens from the same package and between brands of gel inks and ballpoint inks. Homogeneity studies show smaller variation of elemental compositions within a single source than between different sources (i.e. brands and types). It was possible to discriminate between pen markings from different brands and between pen markings from the same brand but different model. Discrimination of ∼ 96-99% was achieved for sets that otherwise would remain inseparable by conventional methods. The results show that elemental analysis, using either LA-ICP-MS or LIBS, provides an effective, practical and robust technique for the discrimination of document paper and gel inks with minimum mass removal (9-15 μg) and minimum damage to the document's substrate.
[en] An ion exchange method was established for the effective removal of sodium matrix for iodine determination by ICP-TOF-MS technique. Since the direct determination of trace level analytes in the presence of heavy matrix is not recommended by this technique. Therefore, the removal of matrix is essentially required to achieve better detection limits and to avoid memory effects. The extraction system was designed for the removal of matrix prior to the analysis by ICP-MS, various parameters were optimized to achieve efficient removal of matrix. The accuracy of the method was evaluated by spiking salt samples with known amount of iodine (50 mu g/g) and % recoveries were calculated. The recoveries obtained were > 98% with relative standard deviation (RSD) < 5%. The established method was applied for the analysis of commercially available iodized table salt samples. The results and % recoveries are given. The most commonly used iodo metric titration method is not satisfactory as it has 5-10 % quantitative error. Our method is reliable and could be conveniently applied for the determination of iodine in table salt samples. (Orig./A.B.)