Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 234U and 230Th determination method based on an extraction chromatographic separation on a flow injection system coupled to a quadruple ICP-MS was developed. Two-milliliter UTEVA (Eichrom Co.) cartridges were applied as separation tool and 236U and 229Th as spikes. Loading and washing steps were carried out in 3 M HNO3 solution and 0.05 M ammonium oxalate applied to elute both uranium and thorium. The method was applied initially to the IAEA-327 soil reference sample and NIST SRM 4357 ocean sediment reference material, with the obtained 234U and 230Th concentrations in agreement with the reference levels. Samples from a deep-sea sediment core (2450 m water depth) were analyzed and based on 230Th/234U dating, a mean sedimentation rate of 3.3 cm ky(-1) was calculated. Samples from two sediment layers were also dated by 14C-AMS and the observed ages agree with the 230Th/234U results.
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PMID:234U and 230Th determination by FIA-ICP-MS and application to uranium-series disequilibrium in marine samples. 1654 93

An on-line Hg reduction technique using stannous chloride as the reductant was applied for accurate and precise mercury isotope ratio determinations by multi-collector (MC)-ICP/MS. Special attention has been paid to ensure optimal conditions (such as acquisition time and mercury concentration) allowing precision measurements good enough to be able to significantly detect the anticipated small differences in Hg isotope ratios in nature. Typically, internal precision was better than 0.002% (1 RSE) on all Hg ratios investigated as long as approximately 20 ng of Hg was measured with a 10-min acquisition time. Introducing higher amounts of mercury (50 ng Hg) improved the internal precision to <0.001%. Instrumental mass bias was corrected using (205)Tl/(203)Tl correction coupled to a standard-sample bracketing approach. The large number of data acquired allowed us to validate the consistency of our measurements over a one-year period. On average, the short-term uncertainty determined by repeated runs of NIST SRM 1641d Hg standard during a single day was <0.006% (1 RSD) for all isotope pairs investigated ((202)Hg/(198)Hg, (202)Hg/(199)Hg, (202)Hg/(200)Hg, and (202)Hg/(201)Hg). The precision fell to <0.01% if the long-term reproducibility, taken over 11 months (over 100 measurements), was considered. The extent of fractionation has been investigated in a series of sediments subject to various Hg sources from different locations worldwide. The ratio (202)Hg/(198)Hg expressed as delta values (per mil deviations relative to NIST SRM 1641d Hg standard solution) displayed differences from +0.74 to -4.00 per thousand. The magnitude of the Hg fractionation per amu was constant within one type of sample and did not exceed 1.00 per thousand. Considering all results (the reproducibility of Hg standard solutions, reference sediment samples, and the examination of natural samples), the analytical error of our delta values for the overall method was within +/-0.28 per thousand (1 SD), which was an order of magnitude lower than the extent of fractionation (4.74 per thousand) observed in sediments. This study confirmed that analytical techniques have reached a level of long-term precision and accuracy that is sufficiently sensitive to detect even small differences in Hg isotope ratios that occur within one type of samples (e.g., between different sediments) and so far have unequivocally shown that Hg isotope ratios in sediments vary within approximately 5 per thousand.
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PMID:High-precision measurement of mercury isotope ratios in sediments using cold-vapor generation multi-collector inductively coupled plasma mass spectrometry. 1655 Apr 18

After decomposition of plant standard reference materials bush twigs and leaves (GBW07602, GBW07603), poplar leaves (GBW07604) and tea (GBW07605) with either dry ashing method or wet digestion method, all kinds of fine particles left in the solution were collected and examined carefully by a scanning electron microscope (SEM), and their chemical composition were investigated by a SEM-affiliated energy-dispersive X-ray spectrometer at the same time. Moreover, the concentrations of some metal elements distributed among four different tea SRM-originated particle fractions extracted following the BCR sequential extraction procedure were determined by AAS and ICP-AES. It was found that decomposition methods have a great influence on the structure of fine particles. When dry ashing method is used, grey-colored, fluffy and porous partices can be produced, whereas fewer white-colored, compact particles can be produced when another method is used. As for chemical composition, all kinds of fine particles are almost the same, with silicon and aluminium as their main constituents, and calcium, iron, potassium, titanium and so on as their minor ones. The elementaI distribution percentages in four different particle fractions in two kinds of plant-originated particles differ from element to element, which can result in severe negative errors when plant samples are decomposed and determined for elemental concentrations.
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PMID:[Study on the characteristics and compositions of fine particles left in the solution after decomposition of plant samples]. 1682 24

The spatial distribution and concentration of impurities in metallurgical-grade silicon (MG-Si) samples (97-99% w/w Si) were investigated by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The spatial resolution (120 mum) and low limits of detection (mg kg(-1)) for quality assurance of such materials were studied in detail. The volume-dependent precision and accuracy of non-matrix-matched calibration for quantification of minor elements, using NIST SRM 610 (silicate standard), indicates that LA-ICP-MS is well suited to rapid process control of such materials. Quantitative results from LA-ICP-MS were compared with previously reported literature data obtained by use of ICP-OES and rf-GD-OES. In particular, the distribution of element impurities and their relationship to their different segregation coefficients in silicon is demonstrated.
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PMID:Laser ablation inductively coupled plasma mass spectrometry for direct analysis of the spatial distribution of trace elements in metallurgical-grade silicon. 1690 87

Slurry sampling electrothermal vaporization dynamic reaction cell inductively coupled plasma mass spectrometry (ETV-DRC-ICP-MS) has been applied to determine Fe, Co, Ni, Cu, and Zn in biological samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Pd was used as the modifier. The effectiveness of the ETV sample introduction technique and dynamic reaction cell in alleviating various spectral interferences in ICP-MS analysis has been demonstrated. This method has been applied to determine Fe, Co, Ni, Cu, and Zn in NIST SRM 1573a tomato leaves reference material and NRCC DORM-2 dogfish muscle reference material and also real samples such as a tea and a swordfish sample purchased locally. Since the sensitivities of the elements studied in slurry and aqueous solution were different, an analyte addition technique was used for the determinations. The analytical results of the reference materials agreed with the certified values. The precision between sample replicates was better than 6% for all determinations. The method detection limit estimated from analyte addition curves was 0.01, 0.006, 0.007, 0.004, and 0.006 microg g(-1) for Fe, Co, Ni, Cu, and Zn, respectively, in the original biological samples.
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PMID:Electrothermal vaporization dynamic reaction cell inductively coupled plasma mass spectrometry for the determination of Fe, Co, Ni, Cu, and Zn in biological samples. 1729 99

In this study, we examined the influence of the matrix on rare earth element (REE) analyses of carbonate with laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) using carbonate and NIST glass standards. A UV 213 nm Nd:YAG laser system was coupled to an ICP-MS. Laser-ablation was carried out in both He and Ar atmospheres to investigate the influence of ablation gas on the analytical results. A small amount of N2 gas was added to the carrier gas to enhance the signal intensities. Synthetic CaCO3 standards, doped with REEs, as well as NIST glasses (NIST SRM 610 and 612) were used as calibration standards. Carbonatite, which is composed of pure calcite, was analyzed as carbonate samples. The degree of the influence of the matrix on the results was evaluated by comparing the results, which were calibrated by the synthetic CaCO3 and NIST glass standards. With laser-ablation in a He atmosphere, the differences between the results calibrated by the synthetic CaCO3 and NIST glass standards were less than 10% across the REE series, except for those of La which were 25%. In contrast, for the measurements made in an Ar atmosphere, the results calibrated by the synthetic CaCO3 and NIST glass standards differed by 25-40%. It was demonstrated that the LA-ICP-MS system can provide quantitative analysis of REE concentrations in carbonate samples using non matrix-matched standards of NIST glasses.
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PMID:Determination of rare earth element in carbonate using laser-ablation inductively-coupled plasma mass spectrometry: an examination of the influence of the matrix on laser-ablation inductively-coupled plasma mass spectrometry analysis. 1738 60

Slurry sampling electrothermal vaporization (ETV) inductively coupled plasma mass spectrometry (ICP-MS) has been applied to determine As and Se in soil and sludge samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Pd and ascorbic acid were used as mixed modifiers to enhance the ion signals. The effectiveness of ETV sample introduction technique for alleviating various spectral interferences in ICP-MS analysis has been demonstrated. This method has been applied to determine As and Se in NIST SRM 2709 San Joaquin soil reference material and NIST SRM 2781 domestic sludge reference material and a farmland soil sample collected locally. Since the sensitivities of As and Se in slurry solution and aqueous solution were different, analyte addition technique was used to determine As and Se in these samples. The As and Se analysis results of the reference materials agreed with the certified values. The precision between sample replicates was better than 5% for all determinations. The method detection limit estimated from analyte addition curves was about 0.03 and 0.02 microg g(-1) for As and Se, respectively, in original soil and sludge samples.
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PMID:Slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of As and Se in soil and sludge. 1738 7

A method of fluorination assisted electrothermal vaporization (FETV)-ICP-MS with polytetrafluoroethylene as fluorinating reagent was developed for the direct determination of trace rare earth elements (REEs) in coal fly ash and atmospheric particulates. Under the optimal conditions, the detection limits for REEs were 0.1 pg m(-3)(Eu) to 6.7 pg m(-3)(Nd) with the precisions of 4.1%(Yb) to 10%(La) (c=1 microg L(-1), n=9). The proposed method was applied to determine trace REEs in coal fly ash, airborne particulates and NIES SRM No. 8 Vehicle Exhaust Particulates. It was found that the determined values for Y, La, Pr and Nd obtained by slurry sampling FETV-ICP-MS with external calibration coincided with that obtained by pneumatic nebulization (PN)-ICP-MS and slurry sampling FETV-ICP-MS with standard addition. However, the determined values for Ce and Sm obtained by slurry sampling FETV-ICP-MS with external calibration were lower than that obtained by PN-ICP-MS and slurry sampling FETV-ICP-MS with standard addition.
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PMID:Determination of trace rare earth elements in coal fly ash and atmospheric particulates by electrothermal vaporization inductively coupled plasma mass spectrometry with slurry sampling. 1746 23

A demountable design of the static high sensitivity ICP (SHIP) for optical emission spectrometry is presented, and its use as an excitation source with the introduction of wet aerosols was investigated. Aerosols were produced by standard pneumatic sample introduction systems, namely a cross flow nebulizer, Meinhard nebulizer and PFA low flow nebulizer, which have been applied in conjunction with a double pass and a cyclonic spray chamber. The analytical capabilities of these sample introduction systems in combination with the SHIP system were evaluated with respect to the achieved sensitivity. It was found that a nebulizer tailored for low argon flow rates (0.3-0.5 L min(-1)) is best suited for the low flow plasma (SHIP). An optimization of all gas flow rates of the SHIP system with the PFA low flow nebulizer was carried out in a two-dimensional way with the signal to background ratio (SBR) and the robustness as optimization target parameters. Optimum conditions for a torch model with 1-mm injector tube were 0.25 and 0.36 L min(-1) for the plasma gas and the nebulizer gas, respectively. A torch model with a 2-mm injector tube was optimized to 0.4 L min(-1) for the plasma gas and 0.44 L min(-1) for the nebulizer gas. In both cases the SHIP system saves approximately 95% of the argon consumed by conventional inductively coupled plasma systems. The limits of detection were found to be in the low microgram per litre range and below for many elements, which was quite comparable to those of the conventional setup. Furthermore, the short-term stability and the wash out behaviour of the SHIP were investigated. Direct comparison with the conventional setup indicated that no remarkable memory effects were caused by the closed design of the torch. The analysis of a NIST SRM 1643e (Trace Elements in Water) with the SHIP yielded recoveries of 97-103% for 13 elements, measured simultaneously.
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PMID:Introducing wet aerosols into the static high sensitivity ICP (SHIP). 1759 58

A method for the direct multi-element determination of Cl, S, Hg, Pb, Cd, U, Br, Cr, Cu, Fe, and Zn in powdered coal samples has been developed by applying inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with laser-assisted introduction into the plasma. A sector-field ICP-MS with a mass resolution of 4,000 and a high-ablation rate laser ablation system provided significantly better sensitivity, detection limits, and accuracy compared to a conventional laser ablation system coupled with a quadrupole ICP-MS. The sensitivity ranges from about 590 cps for (35)Cl+ to more than 6 x 10(5) cps for (238)U+ for 1 microg of trace element per gram of coal sample. Detection limits vary from 450 ng g(-1) for chlorine and 18 ng g(-1) for sulfur to 9.5 pg g(-1) for mercury and 0.3 pg g(-1) for uranium. Analyses of minor and trace elements in four certified reference materials (BCR-180 Gas Coal, BCR-331 Steam Coal, SRM 1632c Trace Elements in Coal, SRM 1635 Trace Elements in Coal) yielded good agreement of usually not more than 5% deviation from the certified values and precisions of less than 10% relative standard deviation for most elements. Higher relative standard deviations were found for particular elements such as Hg and Cd caused by inhomogeneities due to associations of these elements within micro-inclusions in coal which was demonstrated for Hg in SRM 1635, SRM 1632c, and another standard reference material (SRM 2682b, Sulfur and Mercury in Coal). The developed LA-ICP-IDMS method with its simple sample pretreatment opens the possibility for accurate, fast, and highly sensitive determinations of environmentally critical contaminants in coal as well as of trace impurities in similar sample materials like graphite powder and activated charcoal on a routine basis.
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PMID:Development of an accurate, sensitive, and robust isotope dilution laser ablation ICP-MS method for simultaneous multi-element analysis (chlorine, sulfur, and heavy metals) in coal samples. 1765 33


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