Sample container, aluminium

Figure 2 The surface area of aluminas calcined at lOOCPC for 2h. The samples contained aluminium sulphate produced from gibbsite. The abscissae shows the fractional conversion of the gibbsite.

These techniques are generally more than adequate for many plastic or standard quality metallised films but can hardly discriminate between samples containing aluminium foil, which generally have water transmission rates much lower than this value. 

Salgado Ordonez et al. [28] used di-2-pyridylketone 2-furoyl-hydrazone as a reagent for the fluorometric determination of down to 0.2 pg aluminium in seawater. A buffer solution at pH 6.3, and 1 ml of the reagent solution were added to the samples containing between 0.25 to 2.50 pg aluminium. Fluorescence was measured at 465 nm, and the aluminium in the sample determined either from a calibration graph prepared under the same conditions or a standard addition procedure. Aluminium could be determined in the 10-100 pg/1 range. The method was satisfactorily applied to spiked and natural seawater samples. 

Precautions may also have to be taken to prevent loss or gain of moisture, and to prevent photochemical degradation. Light-sensitive samples should be stored in the dark, in amber glass containers or in glass containers protected by aluminium foil. Samples containing volatile constituents should be kept in well-sealed containers and preferably stored in the cold to reduce the vapour pressure of such compounds. 

The sample containers most commonly used are cylindrical pans pressed from pure aluminium foil. Alternative materials are used for very high temperatures or corrosive substances, and hermetically sealed pans to withstand several atmospheres pressure can be used for volatile materials. Some heat flux DSC instruments are available which are capable of operation at high pressures, by means of containment of the DSC cell within a pressure vessel. 

Ross et al. [6] analysed samples of soil leachates from laboratory columns and of soil pore water from field porous cup lysimeters for aluminium by atomic absorption spectrometry under two sets of instrumental conditions. Method 1 employed uncoated graphite tubes and wall atomisation method 2 employed a graphite furnace with a pyrolytically coated platform and tubes. Aluminium standards were prepared and calibration curves used for the colorimetric quantification of aluminium. Method 1 gave results which compared favourably with method 2 in terms of both sensitivity and interference reduction for samples containing 1-15 uM aluminium. 

Stabilities of lake and tap water samples for aluminium speciation were investigated (Fairman etal., 1994). Concentrations of 25-1000mgl 1 total aluminium in high-density polyethylene containers were stable for 30 days. Thereafter, increases in pH resulted in the precipitation of aluminium hydroxy species. 

Shinozuka et al. [91] developed a sensitive method for the determination of four anthranilic acid derivatives (diclofenac sodium, aluminium flufenamate, mefenamic and tolfenamic acids) by HPLC procedure. The four drugs were converted into methylphthalimide (MPI) derivatives in a constant yield by reaction with /V-chloromethylphthalimide at 60°C for 30 min. The production of the MPI derivatives were confirmed by mass spectrometry. The MPI derivatives of the four drugs were separated by HPLC using a C-18 bonded phase LiChrospher RP-18 column (250 x 4 mm i.d.) with acetonitrile-water (80 20, v/v) as mobile phase. The flow rate was 0.8 mL/min. The UV absorbance was measured at 282 nm. The calibration curves of the MPI derivatives of the drugs were linear from 1.0 to 5.0 pg/rnL. The detection limits of the four drugs were 0.5-5 ng. The extraction procedure for the four anthranilic acid derivatives added in the plasma and urine was performed by using Extrelut 1 column. Yields of column extraction of 100 pL of plasma and urine samples (containing 0.5 pg of anthranilic acid derivatives) with 6 mL of ethyl acetate were 84-106%. 

NMR-characterization. 27 Corbin et al. (35) were able to show by a systematic study that Z/A1 MAS NMR gives the true Si/Al ratio with a mean error of 10 %, if two conditions are met a) The amount of paramagnetic species is less than 0.05 % and b) the sample does not contain "NMR-invisible" aluminium. Chemical analyses of the samples under study showed that condition one is fulfilled. If samples contain "NMR-invisible" aluminium a difference between the concentration determined by chemical analysis and the framework aluminium concentration determined by NMR should be observed. From the absence of such a difference we conclude that "NMR-invisible" aluminium species do not exist in our samples. Also a line at the position of about 0 ppm due to octahedrally coordinated non-framework aluminium and a broad line at about 30 ppm due to tetrahedrally coordinated nonframework aluminium (36) could not be observed. The values for the concentration of framework aluminium atoms derived from the intensities of the line at about 60 ppm (see below) are in good agreement with those corresponding to the amount of alumina used in the synthesis mixtures. In conclusion, through the Al MAS NMR measurements it was possible to show that all aluminium atoms are incorporated in tetrahedrally oxygen coordinated framework positions. 

Kooli, F., Rives, V. and Ulibarri, M. A. (1995). Preparation and study of decavanadate-pillared hydrotalcite-like anionic clays containing transition metal cations in the layers. 1. Samples containing nickel-aluminium prepared by anionic exchange and reconstruction. Inorg. Chem. 34, 5114. 

One study has suggested that researchers looking for a connection between aluminium and Alzheimer s disease may have ignored the most important source of aluminium for the average person—foodstuffs that contain aluminium additives (36). The results implied that aluminium, added to such foods as anticaking agents, emulsifiers, thickeners, leaveners, and stabilizers, may have long-term adverse effects on health. However, the small sample size hampers any definitive conclusions, the odds ratios were very unstable, and the study had limited statistical power to rule out random errors. 

The research of adsorption properties has shown, that adsorption isotherms of benzene for dealuminated (NH4)2SiF6 zeolite lay below adsorption isotherms of benzene for NaY obtained even at more high adsorption temperatures. In a fig. 1 are shown adsorption isotherms for a sample 2. It is characteristic that at different temperatures (180, 200, 230 C) isotherms are not divided. Apparently, it is connected that so a little benzene is kept on a surface, that the distinction in adsorption at given temperature interval is not fixed. Probably, the samples contain impurities of complex compounds of aluminium with fluorine, that is agreed XRD data. Also relative concentration of defect sites of structure is increased during dealumination, that also can affect on adsorption property. 

Sample containers are thin-walled cells of either aluminium or vanadium. Vanadium is required if diffraction measurements are to be included. Solids can be simply wrapped in aluminium foil. Liquids, however, must be held in sealed cans. Indium wire provides a good seal, because it is ductile, easily created and, more importantly, it has a very low coefficient of thermal expansion. Thus a can that is sealed at room temperature will remain sealed after having been cycled to 20K. If the compounds are air or moisture sensitive (solid or liquid) they are loaded into the cans in a glove-box. Gases are more problematic, one successful method is have a suitable volume of the gas attached above the cell. The whole is lowered into the cryostat where the gas is first liquefied and allowed to fill the cell, subsequently the temperature is lowered to freeze the liquid. 

Pitchblende is one of the most fertile sources of radioactive material. Its composition varies widely, but it always contains an oxide of uranium, associated with oxides of other metals, especially copper, silver, and bismuth the Austrian mineral contains cobalt and nickel the American, samples contain no cobalt or nickel but are largely associated with iron pyrites and arsenic zinc, manganese, and the rare earths are frequently present, while occasionally calcium, barium, aluminium, zirconium, thorium, columbium, and tantalum are reported. Dissolved gases, especially nitrogen and helium, are present in small proportions. 

The Si, Al, P composition is generally not homogeneous throughout the individual SAPO-n crystals [4]. SAPO-n crystals contain aluminosilicate domains (SA), where the silicon is concentrated, and silicoaluminophosphate (SAPO) domains. The Brpnsted acid sites of the SAPO-5 crystals of this work are located in the SAPO domains [21]. The SA domains do not contain aluminium and are catalytically inactive [21]. The Si(4Al) environment generates the Br0nsted acidity in SAPO-5. It represents 4% of the Si+A1 + P atoms in this particular sample [21]. In the SAPO-11 crystals used in this work, the Brqnsted acid sites are located in the SA crystal domains and at the interface of SA and SAPO domains [21]. Si(nAl) environments responsible for the Brpnsted acidity of SAPO-11 are not resolved from the 29 i resonance envelop (Fig.6). Their amount was estimated at ca. 1% of the Si+Al+P atoms [21]. 

In general, absorbers can be metal foils, compacted powders, mixtures with inert solid diluents, mixtures with inert greases, frozen liquids, or frozen solutions. The only limitation is on the material used for the windows of the sample container this must be free of the resonant isotope and have a low mass attenuation coefficient for the y-ray being studied. Organic plastics and aluminium foil are most commonly used. 

The aluminium cover of a DSC-2 system was replaced by a polycarbonate cover (see Figure 1.22) provided with a spring loaded, moveable magnetic system to remove the mild steel lids from the sample containers, while the DSC cell is closed. Two experimental parameters can be varied to vaporise samples with boiling temperatures ranging from 50°C to 200°C within maximal 30 minutes i.e. the sample container hole diameter and the sample weight. Besides, the DSC sensitivity can be varied. 

ALPO-5 samples contained a minor amount (<5%) of cristobalite however, a pure sample of this dense phase was found to be inactive in catalytic experiments. The phosphorus/aluminium ratio was 1 within experimental error ( 3 %). SAPO-5 had the composition AI P Si = 1 0.98 0.06. 

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