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 flow-injection atomic absorption spectrometric method was developed for the determination of trace amounts of arsenic and selenium in proposed spinach and tomato leaves standard reference materials (SRM 1570a and SRM 1573a). The samples were digested with HNO(3), H(2)SO(4) and HClO(4) using reflux column. The experimental details for sample preparation and the flow injection hydride generation method are discussed. The effect of matrix and various acid concentrations on the extraction and absorbance was also studied. The method has detection limits of 0. 15 ng As/ml and 0.17 ng Se/ml. Standard Reference Materials (SRM 1571 and 1547) were analyzed and the results agreed well with the certified values.
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PMID:Determination of arsenic and selenium in spinach and tomato leaves reference materials using flow injection and atomic absorption spectrometry. 1896 33

A simple flow injection on-line dilution procedure with detection by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of copper, zinc, arsenic, lead, selenium, nickel and molybdenum in human urine. Matrix effects were minimized by employing a dilution factor of 16.5 with on-line standard addition, and (103)Rh was used as internal standard to compensate for signal fluctuation. The procedure was validated by the analysis of two standard reference materials SRM 2670 (NIST) and Seronormtrade mark Trace Elements in Urine. Recovery experiments were performed by spiking the reference materials as well as artificial urine. The detection limits (mug l(-1)) were 0.12,0.96,0.30,0.09,0.45,0.08,0.09, and the precisions (RSD,%) were 2.6,2.3,3.0,3.7,3.7,4.9,2.8 for Cu, Zn, As, Pb, Se, Ni and Mo, respectively. The procedure was applied to the analysis of 41 human urine samples. No correlations between the concentrations of the elements were observed.
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PMID:Flow injection on-line dilution for multi-element determination in human urine with detection by inductively coupled plasma mass spectrometry. 1896 53

A sequential extraction procedure for separating inorganic species of selenium in particulate matter of emissions and working areas, has been developed. The proposed procedure has been tested first on synthetic samples prepared in laboratory with the different selenium salts, then in the presence of atmospherical particulate matter sampled in a laboratory of the department of general chemistry, previously checked for the absence of selenium. Finally the speciation was tested on a reference material (urban particulate matter NIST SRM 1648), certified for the total selenium content. The sample was first treated with the proposed procedure, followed by an evaluation of matrix spiking and recovery analyses. The repeatability of the selenium speciation was assessed by performing multiple analyses of the spiked samples. Quantitative determinations have been made by AAS and voltammetry. The possible interferences of the most common ions have been investigated.
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PMID:Sequential extraction procedure for speciation of inorganic selenium in emissions and working areas. 1896 57

A new analytical method has been developed for the determination of total gaseous selenium in the atmosphere by honeycomb denuder collection followed by differential pulse cathodic stripping voltammetry (DPCSV) measurement. Gaseous selenium was collected in a denuder coating solution containing 2% HNO(3) and 2% glycerine. The soluble product, selenious acid, was then extracted by water for DPCSV analysis. The collection efficiency for gaseous selenium was 99.1% at a flow rate of 1 l min(-1) for 3 h. Excellent linearity in DPCSV was maintained up to Se concentration of 40 ng ml(-1). This was equivalent to a working concentration of 220 ng m(-3) of selenium in the atmosphere. A precision of 1.26% RSD (n=5) for 5 ng Se was obtained, and the detection limit (3sigma) and the quantitative determination limit were estimated to be 0.96 and 3.19 ng m(-3). The average recovery of selenium in three standard samples prepared by independent digestion of NIST SRM 1648 (Urban Particulate Matter) using our analytical system was 99.0%. The total content of gaseous selenium in the atmosphere of our laboratories was 3.2-4.4 ng m(-3).
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PMID:Determination of total gaseous selenium in atmosphere by honeycomb denuder/differential pulse cathodic stripping voltammetry. 1896 33

A simple solid phase extraction procedure for speciation of selenium(IV) and selenium(VI) in environmental samples has been proposed prior to graphite furnace atomic absorption spectrometry. The method is based on the solid phase extraction of the selenium(IV)-ammonium pyrrolidine dithiocarbamate (APDC) chelate on the Diaion HP-2MG. After reduction of Se(VI) by heating the samples in the microwave oven with 4moll(-1) HCl, the system was applied to the total selenium. Se(VI) was calculated as the difference between the total selenium content and Se(IV) content. The experimental parameters, pH, amounts of reagents, eluent type and sample volume were optimized. The recoveries of analytes were found greater than 95%. No appreciable matrix effects were observed. The adsorption capacity of sorbent was 5.20mgg(-1) Se (IV). The detection limit of Se (IV) (3sigma, n=11) is 0.010mugl(-1). The preconcentration factor for the presented system was 100. The proposed method was applied to the speciation of selenium(IV), selenium(VI) and determination of total selenium in natural waters and microwave digested soil, garlic, onion, rice, wheat and hazelnut samples harvested various locations in Turkey with satisfactory results. In order to verify the accuracy of the method, certified reference materials (NIST SRM 2711 Montana Soil, NIST SRM 1568a Rice Flour and NIST SRM 8418 Wheat Gluten) were analyzed and the results obtained were in good agreement with the certified values. The relative errors and relative standard deviations were below 6 and 10%, respectively.
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PMID:Speciation of selenium(IV) and selenium(VI) in environmental samples by the combination of graphite furnace atomic absorption spectrometric determination and solid phase extraction on Diaion HP-2MG. 1907 60

A flow injection hydride manifold was coupled to a 150W tungsten coil electrothermal atomizer for in situ hydride collection followed by selenium and arsenic determination by ET AAS. Rhodium (200mug), thermally reduced over the double layer tungsten atomizer, was very efficient at collecting selenium or arsenic hydrides. Prior to analysis, biological samples were digested in closed-vessels microwave digestion system. Prior to the hydride formation, both selenium and arsenic were reduced to valence state (IV) and (III), respectively. The detection limit was 35ngL(-1) for selenium and 110ngL(-1) for arsenic. Sample throughput was 70h(-1) using 30s of hydride trapping time. Method accuracy was evaluated by analyzing biological-certified reference materials from the National Institute of Standard and Technology (SRM-1577a and SRM-1577b "bovine liver" and RM-8414 "bovine muscle powder") and from the International Agency for Energy Atomic (A-13 "animal blood") and one water-certified reference material from the National Institute of Standard and Technology (SRM-1640 trace elements in natural water). By applying a t-test, there was no significant difference at the 95% probability level between the results obtained with the proposed method and those certified values.
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PMID:Exploiting in situ hydride trapping in tungsten coil atomizer for Se and As determination in biological and water samples. 1907 55

Innovative research and diagnostic techniques for biological testing have advanced during recent years because of the development of semiconductor nanocrystals. Although these commercially available, fluorescent nanocrystals have a protective organic coating, the inner core contains cadmium and selenium. Because these metals have the potential for detrimental environmental effects, concerns have been raised over our lack of understanding about the environmental fate of these products. U.S. Environmental Protection Agency test protocol and fluorescence microscopy were used to determine the fate and effect of quantum dots (QDs; Qdot 545 ITK Carboxyl Quantum Dots [Fisher Scientific, Fisher part Q21391MP; Invitrogen Molecular Probes, Eugene, OR, USA]) using standard aquatic test organisms. No lethality was measured following 48-h exposure of Ceriodaphnia dubia to QD suspensions as high as 110 ppb, but the 96-h median lethal concentration to Pseudokirchneriella subcapitata was measured at 37.1 ppb. Transfer of QDs from dosed algae to C. dubia was verified with fluorescence microscopy. These results indicate that coatings present on nanocrystals provide protection from metal toxicity during laboratory exposures but that the transfer of core metals from intact nanocrystals may occur at levels well above toxic threshold values, indicating the potential exposure of higher trophic levels. Studies regarding the fate and effects of nanoparticles can be incorporated into models for predictive toxicology of these emerging contaminants.
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PMID:Aqueous toxicity and food chain transfer of Quantum DOTs in freshwater algae and Ceriodaphnia dubia. 1908 11

A microwave-assisted enzymatic extraction (MAEE) method was developed for the simultaneous extraction of arsenic (As) and selenium (Se) species in rice products. The total arsenic and selenium content in the enzymatic extracts were determined by inductively coupled plasma mass spectrometry (ICP-MS), while the speciation analysis was performed by ion chromatography coupled to inductively coupled plasma-mass spectrometry (IC-ICP-MS). The main factors affecting the enzymatic extraction process were evaluated in NIST SRM-1568a rice flour. The optimum extraction conditions were 500 mg of sample, 50 mg of protease XIV, and 25 mg of alpha-amylase in aqueous medium during 40 min at 37 degrees C. The extraction recoveries of total As and Se reached 100 +/- 3 and 80 +/- 4%, respectively. The species stability study during the MAEE process did not show transformation of the target species in rice products. The results of As speciation obtained for SRM-1568a were in agreement with previous studies of As speciation performed on the same reference material. The proposed method was applied to the determination of As and Se species in rice and rice-based cereals. Arsenite [As(III)], arsenate [As(V)], dimethylarsinic acid (DMA), and selenomethionine (SeMet) were the predominant species identified in rice products.
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PMID:Simultaneous extraction of arsenic and selenium species from rice products by microwave-assisted enzymatic extraction and analysis by ion chromatography-inductively coupled plasma-mass spectrometry. 1930 14

This paper presents a method based on the cloud point extraction for the separation and preconcentration of Se (IV) and Se (VI) in environmental water samples as well as total selenium in animal blood and tissue samples. 3,3'-Diaminobenzidine (DAB) is a selective and sensitive reagent and is known to form an intense yellow compound piazselenol with selenium (IV). When a system consisting of sample, DAB and surfactant Triton X-114 is warmed above the cloud point of the surfactant, it was seen that the DAB-Se (IV) complex gets extracted into the surfactant rich phase while the Se (VI) remains in the aqueous phase. Se (VI) in the sample was reduced to Se (IV) by microwave heating of solution in 4 mol L(-1) HCl and total Se was estimated by carrying out the CPE. The quantification of selenium was carried out using ETAAS. The analytical parameters for the quantitative cloud point extraction of the Se-DAB complex were investigated and optimized. The proposed procedure was validated by applying it to the determination of the content of Se in Certified Reference Material BND 701-02. (NPL, India). The detection limit of selenium in environmental water samples was 0.0025 microg L(-1) with an enrichment factor of 100. The relative standard deviation (RSD) for ten replicate measurements of 5 microg L(-1) was 3.6%. The proposed method was successfully applied to the determination of selenium (IV), (VI) in environmental water samples and determination of total selenium in human blood, SRM-IAEA-A-13 animal blood and SRM-IAEA-407 fish tissue.
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PMID:Cloud point extraction and electrothermal atomic absorption spectrometry of Se (IV)--3,3'-diaminobenzidine for the estimation of trace amounts of Se (IV) and Se (VI) in environmental water samples and total selenium in animal blood and fish tissue samples. 1993 63

A dynamic reaction cell ICP-MS was used as a CE detector for the speciation analysis of arsenic and selenium. Samples containing arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, selenite, selenate, selenocysteine, selenomethione, and Se-methylselenocysteine were subjected to electrophoretic separation before being introduced into the microconcentric nebulizer (CEI-100) for their determination by ICP-MS. The separation has been achieved in a 60 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used was 25 mmol/L CAPS, and 0.5 mmol/L SDS at pH 9.5, whereas the applied voltage was set at 25 kV. The potentially interfering (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+) at the selenium masses m/z 78 and 80 were reduced in intensity by approximately three orders of magnitude by using 1.4 mL/min CH(4) as reactive cell gas in the dynamic reaction cell. Arsenic was determined as the adduct ion (75)As(12)CH(2) (+) at m/z 89. The LOD for arsenic and selenium was in the range of 0.6-1.8 ng/mL, and 0.5-1.4 ng/mL, respectively, based on peak height. This method has been applied to determine various arsenic and selenium compounds in NIST SRM 1633a Coal Fly Ash and NRCC DOLT-3 Dogfish Liver reference materials and a selenium dietary supplement. The arsenic and selenium compounds were extracted from fish liver and dietary supplement by using Protease XIV and Lipase, and from coal fly ash with HF solution. The spike recoveries were in the range 91-103% for all the species studied.
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PMID:Speciation analysis of arsenic and selenium compounds by CE-dynamic reaction cell-ICP-MS. 2059 4


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