Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Table sampling

The vibration frequencies of C-H bond are noticeably higher for gaseous thiazole than for its dilute solutions in carbon tetrachloride or tor liquid samples (Table 1-27). The molar extinction coefficient and especially the integrated intensity of the same peaks decrease dramatically with dilution (203). Inversely, the y(C(2jH) and y(C(5(H) frequencies are lower for gaseous thiazole than for its solutions, and still lower than for liquid samples (cf. Table 1-27). [Pg.61]

A proportional determinate error, in which the error s magnitude depends on the amount of sample, is more difficult to detect since the result of an analysis is independent of the amount of sample. Table 4.6 outlines an example showing the effect of a positive proportional error of 1.0% on the analysis of a sample that is 50.0% w/w in analyte. In terms of equations 4.4 and 4.5, the reagent blank, Sreag, is an example of a constant determinate error, and the sensitivity, k, may be affected by proportional errors. [Pg.61]

Reject Ho if sample > tabled Accept Ho if sample < tabled... [Pg.500]

Once you have developed the program plan and schedule, and estimated resource requirements, you should organize this information in a manageable form for presentation to your PSM sponsor. If you have kept management informed about your progress you should have a clear idea of what is expected in terms of form, content, and level of detail. A sample table of contents for a project plan appears as Figure 5-12, and Figures 5-13 and 5.14 provide additional detail on selected portions of the plan. [Pg.120]

In an ideal SEC separation, the mechanism is purely sieving, with no chemical interaction between the column matrix and the sample molecules. In practice, however, a small number of weakly charged groups on the surface of all TSK-GEL PW type packings can cause changes in elution order from that of an ideal system. Fortunately, the eluent composition can be varied greatly with TSK-GEL PW columns to be compatible with a wide range of neutral, polar, anionic, and cationic samples. Table 4.8 lists appropriate eluents for GFC of all polymer types on TSK-GEL PW type columns (11). [Pg.111]

FEFO, 1,2 DP and the HN mixts. In all the remaining expls, product compn was strongly affected by confinement. In general, confined samples of these materials produced more C(s) and less CO than unconfined samples Table 5... [Pg.867]

Non o the analyzed samples showed the presence of gels and the low M /M and M /M ratios of the highest molecular weight sample (table I) indicate that the SPP is not susceptible to m.w.d. broadening. [Pg.146]

A smaller number of individuals, 132 samples, was analyzed for stable isotopes of nitrogen. There were two objectives to the nitrogen isotope analysis 1) to determine the amount of animal protein in the diet and to look for variation between the sexes and 2) to determine when infants were weaned from the breast. These objectives were addressed by selecting at least ten individuals, when available, from a number of age classes. Figure 1.1 illustrates the age distribution of the sample. Table 1.3 shows the results of these analyses. Individual 5 N values are provided in Herring et al. (1998). [Pg.8]

This concept was introduced in 1948 by Sondheimer and Kertesz who nsed pH values of 2 and 3.4 for analyses of strawberry jams. Since then, the nse of other pH values has been proposed. Fnleki and Francis (1968) used pH 1 and 4.5 bnffers to measure anthocyanin content in cranberries, and modifications of this techniqne have been applied to a wide range of commodities. The absorbance of anthocy-anins at two different pH levels (1 and 4.5) is measured at Kis-max and at 700 mn, which corrects for haze in the sample (Table 6.3.1). The total monomeric anthocy-... [Pg.484]

How critically interdependent matrix and analytical methods can be is illustrated in the example of the analysis of a soil sample. Table 7.1 shows the method dependent certified values for some common trace elements. The soil had been subjected to a multi-national, multi-laboratory comparison on a number of occasions (Houba et al. 1995) which provided extensive data. The data was subjected to a rigorous statistical program, developed for the USEPA by Kadafar (1982). This process allowed the calculation of certified values for a wide range of inorganic analytes. Uniquely, for the soil there are certified values for four very different sample preparation methods, as follows ... [Pg.239]

Another approach to improving agrochemical detection is to apply more of the active ingredient to increase the initial soil concentration. As mentioned previously, however, one must be careful not to exceed greatly the labeled application rate of the compound as questions may arise as to concentration effects on the observed dissipation. A more common and acceptable approach is to section the upper soil core into smaller depth increments, yielding increased residue concentrations as the total amount of soil mixed with the residues decreases in each processed sample (Table 1). [Pg.851]

Both thermogravimetric analysis and differential scanning calorimetric studies were carried out on modified and unmodified PPO samples. Table IV presents the weight losses and the glass transition temperatures of the most representative polymers. [Pg.51]

Technical parathion samples were analyzed in the same manner as the standard samples (Table I). For dust formulations at least 1 gram was taken for a sample and... [Pg.199]

Diquat and paraquat are quaternary ammonium compounds largely used as contact herbicides and crop desiccants. When systemic absorption occurs, paraquat and diquat are rapidly distributed into the body. Paraquat primarily accumulates in the lungs and kidneys, while the highest diquat concentrations have been found in the gastrointestinal tract, liver, and kidneys (WHO, 1984). Urine is the principal route of excretion for both diquat and paraquat, which are primarily eliminated as unmodified compounds. Occupationally exposed workers can be monitored by measuring paraquat and diquat concentrations in urine samples (Table 6). Blood concentrations are useful to monitor acute poisoning cases. [Pg.11]

Microanalysis is the common name used to refer to a variety of techniques for identifying, characterizing, and evaluating minute amounts of materials. Some microanalytical techniques are scaled-down versions of well-known conventional or physical analytical techniques others are specialized techniques that can be implemented only on extremely small samples. Table 11 lists the minimum size of samples required for microanalysis and the minimum amount of substance detectable by microanalytical techniques (Janssens and Van Grieken 2004). [Pg.63]

The usability of the various available machines, in particular in regard to time-resolved measurements, is proportional to the flux that they are able to shine on the sample. Table 4.1 shows typical data. Modern laboratory instrumentation (rotating anode) is approaching the performance of older synchrotron light sources. [Pg.59]

Perfection of Structure in Nanostructured Materials. An aim of modern nanotechnology is the fabrication of materials with highly perfect structure on the nanometer scale. The distortion of such nanostructured materials can be studied by SAXS methods. Frequently the material is supplied as a very thin film with predominantly uniaxial correlation among the nanodomains. Under these constraints the nanodomains are frequently arranged in such a way that the normal to the film is a symmetry axis rotation of the film on the sample table does not change the scattering (fiber symmetry). [Pg.200]

Mossbauer spectra of calcined samples (Table 1). The Fe3+(3) and Fe3+(4) components are probably located in tetrahedral (framework) positions. The charge distribution around the Fe3+(3) is asymmetric (large QS), thus here the charge compensation is probably provided by Fl+, i.e. indicating the existence of Bronsted sites. The charge symmetry around Fe3+(4) is more symmetric, thus the counterion is probably Na+ or Fe(OFl)+. Fe2+ ions are probably located outside of the framework (due to their larger ionic radius). Thus, in the hydrogen a small part of Fe3+ is reduced to Fe2+, and is probable removed to extra-framework sites. [Pg.114]

The chemical analysis by ICP-AES showed that the determined M2+/M3+ molar ratio in Zn2Al (Table 1) was very close to the nominal ratio of the synthesis mixture, and is supporting the XRD results. For Zn2Ga, the Zn/Ga ratio was slightly higher than 2 due to the presence of an excess of ZnO, also evidenced by XRD. ICP-AES analysis of the Rh exchanged LDH indicated a similar Rh content in the two samples (Table 1). The TPPTS Rh (wt%) ratio was found to be a value of 2.83, in agreement with the structure of the expected complex [9c]. [Pg.305]

These data clearly indicate that the NiMCM-36 catalyst exhibits very interesting properties for ethylene oligomerization, by comparison with the microporous NiMCM-22 zeolite at both reaction temperatures (70 and 150°C, respectively). Compared with other catalysts, the NiMCM-36 behaviour is intermediate between Ni-exchanged dealuminated Y zeolite and Ni-exchanged mesoporous materials. Taking into account that the amount of Ni2+ sites is near the same for all samples (Table 1), in order to explain these differences in catalytic behaviors, two mains categories of properties could be considered (i) the concentration and strength of acid and nickel sites and (ii) the diffusional properties (determined by the size and the architecture of pores). [Pg.387]

The potential for the employment of plasma emission spectrometry is enormous and it is finding use in almost every field where trace element analysis is carried out. Some seventy elements, including most metals and some non-metals, such as phosphorus and carbon, may be determined individually or in parallel. As many as thirty or more elements may be determined on the same sample. Table 8.4 is illustrative of elements which may be analysed and compares detection limits for plasma emission with those for ICP-MS and atomic absorption. Rocks, soils, waters and biological tissue are typical of samples to which the method may be applied. In geochemistry, and in quality control of potable waters and pollution studies in general, the multi-element capability and wide (105) dynamic range of the method are of great value. Plasma emission spectrometry is well established as a routine method of analysis in these areas. [Pg.305]

When the 575 remaining Coso spectra (from samples not used in the 5-class model) were tested against the model, 574 out of 575 were correctly classified with the other Coso samples in the model. In other words, the model remains valid even for unknown samples (Table 2). [Pg.286]

Limits of detection (LOD) and limits of quantification (LOQ) for C and S have been evaluated through consecutive measurements of blank crucibles containing accelerator reagents without any sample (Table 3). [Pg.504]


See other pages where Table sampling is mentioned: [Pg.128]    [Pg.304]    [Pg.306]    [Pg.203]    [Pg.501]    [Pg.2197]    [Pg.219]    [Pg.149]    [Pg.152]    [Pg.514]    [Pg.123]    [Pg.485]    [Pg.485]    [Pg.975]    [Pg.339]    [Pg.342]    [Pg.124]    [Pg.339]    [Pg.358]    [Pg.37]    [Pg.131]    [Pg.72]    [Pg.41]    [Pg.442]    [Pg.175]    [Pg.1286]    [Pg.1459]   
See also in sourсe #XX -- [ Pg.437 ]




SEARCH



Operating limits sample tables

Sample Analysis Tables

Sample apertures table

Sample table

Sample table

Table, circular rotating sample

© 2024 chempedia.info