Powdered samples

SORPTOMETER (PERKIN-ELMER). This method is essentially a gas-chromatographic technique with the sample powder in place of the normal chromatographic column. A mixt of He and N2 is passed thru the sample and the concn of N2 in the exit gas is measured by thermal conductivity or gas-density methods,... 

Examples of using reference samples for calibration can be found in several chapters of the uses Methods for Geochemical Analysis (Baedecker 1987). Solid reference sample powders are used in cahbrating the dc arc emission, energy-dispersive X-ray and instrumental neutron activation analyses described, while acid-dissolved rock reference samples are used for IGP emission analyses and fused reference samples are used for wavelength-dispersive X-ray analyses. 

The morphology of the PVC/rubber-blends depends primarily on the maximum temperature reached during manufacturing and to a limited extend on the history of the sample (powder blending or graft polymerization). 

A calibration set containing between 7-9 gg mL of Apt, 1-3 gg mL" of Ace-K, and 2-4 gg mL of Sac was used. The designed and optimized training set of calibration was applied to the determination of three sweeteners of several synthetic mixtures. The method was also applied to commercial drinks and satisfactorily results were obtained. The procedmes do not require any separation step for colorless sample (powder drink), but only an extraction step for colored beverages (powder and liquid) was used. The effect of cyclamate (CA) and ascorbic acid (AA) was also investigated. 

Transmittance and reflectance data are used in color measurements. Transmittance spectra are used for liquid color measurements, while reflectance spectra are used on solid samples (powders, surfaces) and on opaque liquids (paint). A large number of color scales are in use today. Some are specific to a particular industry, while others enjoy broader application. The most common scales are the CIE L a b (Commission... 

If you don t trust your friend s sample, or don t have any clean friends, you can get powdered urine from Martha Butterfield-Jay Foundation. It s produced by Byrd Labs, and supposedly works perfectly however, I got MBJF s powdered urine, and it did not specify the age or gender of the original sample. Powdered urine must be prepared ahead of time. If there is a period of time that you are clean, you can make powdered urine from your own supply. 

Two types of diffraction measurements are typically made on cosmochemical samples. Powder diffraction, where a sample powder is mounted on the end of a fiber and placed in the X-ray beam, is most commonly used. The term powder in this usage means that the crystal lattice domains are randomly oriented. Powder diffraction is used to identify unknown materials and to determine their basic crystal structure. Single-crystal X-ray diffraction is used to solve the complete structure of crystalline materials. For more details, see Cullity (1978). 

Sample powders were dried in a vacuum oven at 60 C for 7 hours and cooled to minimize the hysteresis effect prior to storage in the dessicators of various water activities. In addition to Drierite, five saturated salt solutions were used in dessicators. These salt solutions were lithium chloride, magnesium chloride, potassium carbonate, sodium nitrite and potassium chloride. Their water activities were 0.110, 0.330, 0.440, 0.650 and 0.850, respectively, at 20 C. Each sample contained 1.2 to 1.5 g powder and four-week equilibration time was employed. The percentage of... 

Extraction (adapted from Bushway 1986 (369)) freeze-dried sample powder stirred in THF-H20-ACN. Extract centrifuged, supernatant collected and concentrated in a rotary evaporator, with added HC1, suspension centrifuged and pH adjusted with NH4OH to pH 10-11. Water bath at 70°C, 30 min. The precipitate collected and boiled in MeOH. Hot suspension filtered and evaporated. ACN-H20 added. 

Neutron diffraction studies have the advantage of being able to determine guest and host (both O and H/D) positions. With the difficulty of preparing single crystals of gas hydrates, most diffraction studies are performed on powder samples. Powder x-ray and neutron diffraction can be used with Rietveld analysis of the data for detailed structure determination (Rawn et al., 2003 Hester et al., 2006a). 

There are numerous ways to prepare a solid sample for XPS-analysis 17K Because of the 360° angle of acceptance, the optimum sample geometry is a cylinder of 11 mm diameter and 2 mm width. However, with a certain loss in sensitivity, flat samples as well as odd shaped samples can be analyzed as well, if they do not exceed the maximum size defined by the vacuum interlock. Sample powders are normally mounted on sticky tape or pressed into a metal grid 17). Excellent results were also obtained by pressing pellets 31) or by subliming the sample directly unto the sample holder. 

Figure 2 shows the structure of this sensor which is similar to that of the potentiometric sensor reported earlier (10). The only difference is that in this sensor a short circuit current between the sensing electrode and the counter electrode is measured with an ammeter. The proton conductor, antimonic acid (Sb205 2H20), was prepared from antimony trioxide and hydrogen peroxide according to a method described elsewhere (7,14). The sample powder was mixed with... 

SEM/EDX Measurements. Sample powder was sprayed onto a carbon coated aluminum sample holder. After drying at room temperature, the sample holder was put into the analysis chamber of an AMRAY 1810D scanning electron microscope and evacuated. 

Self-supported wafers obtained by pressing 7-9 mg/cm2 of the zeolite sample powder at 400 MPa were placed in the cell and then degassed at 673 K. 

The panned heavy mineral concentrates have not generally been analysed unless follow-up work has been carried out. However, all are inspected at site and observed minerals and contaminants are recorded. The samples are an excellent resource for identifying drainage catchment mineralisation and lithologies as well as anthropogenic contamination (Fig. 4.8). Indeed, all the G-BASE excess samples are stored at the National Geological Data Centre, Keyworth, UK, and are available for further study. The value of excess sample powders in research should not be underestimated. 

By diluting a reactive sample powder with an inert powder (e.g. AI2O3), the heat capacity of the sample can be made to match more closely that of the reference, hence baseline float can be dampened. This is a useful technique for reactions of significant thermal effect, e.g. combustion, since sample dilution diminishes the intensity of the differential temperature signal. Since the diluent adds a thermal resistance between the reaction zones and the temperature measuring device, the onset of reactions will shift to higher temperatures. 

The gas release from this reaction can occur quite rapidly and has the reputation for discharging sample powder from the container. 

For the determination of the enthalpies of dissolution of solids in HF, a 5. 5 ml aliquot of 25% HF was placed in the sample cell and the acid was covered with a thin layer ( h) of paraffin oil ( Pro-labo. Rectapur) which is inert to HF. The Kel-F capsule (g) containing the solid was placed on the oil layer. Sufficient buoyancy was ensured by the latter any attack of the sample powder by HF vapor or by the solution was thus avoided. The reference cell contained the same volume of HF than the sample cell. 

---