Gravimetric measurement

In volatilization gravimetry, thermal or chemical energy is used to decompose the sample containing the analyte. The mass of residue remaining after decomposition, the mass of volatile products collected with a suitable trap, or a change in mass due to the loss of volatile material are all gravimetric measurements. 

Industrial Hquid chlorine is routinely analy2ed for moisture, chlorine, other gaseous components, NCl, and mercury foUowing estabHshed procedures (10,79). Moisture and residue content in Hquid chlorine is determined by evaporation at 20°C foUowed by gravimetric measurement of the residue. Eree chlorine levels are estimated quantitatively by thiosulfate titration of iodine Hberated from addition of excess acidified potassium iodide to the gas mixture. 

Owing to the laborious task of obtaining corrosion rates from gravimetric measurements, data for the effect of exposure time on corrosion rates have been very limited. However, with the more recent use of polarisation resistance measurements it would appear that in the absence of macro-biofouling... 

The results of the gravimetric measurements of the hybridization are presented in Table 10. As in the case of fluorescence, normal hybridization results in a frequency shift that is much higher with respect to the unspecific and cold hybridization. Nonspecific hy-... 

TABLE 10 Results of Fluorescent and Gravimetric Measurements of DNA Hybridization Against a Reference Containing only LB-Immobilized Single-Stranded DNA/Amine Sandwich... 

Amount of soluble polymer generated in this reaction (Figure 9) was only 18-19% solids, which was well below the 29% total solids found after reaction completion. Differences between calculated soluble solids and gravimetrically measured total solids were large, but variable, for all three polymerizations studied. Thus, amount of soluble polymer was not proportional to total solids. However, a good correlation between total solids and the sum of refractometer peak areas for both polymer peaks was obtained. Figure 10. This correlation included all three polymerizations and there was little or no batch bias. 

Figure 3.49. Gravimetric measurement of chemisorption of N2O on a supported Cu eatalyst (Luys et al., 1989). Surface and bulk oxidation can be easily discriminated.

When ethanol was added to potassium perchlorate, formed during a gravimetric measuring of potassium, it caused a very violent detonation. 

The penetration front was measured from the images in Figure 3.4.9 and plotted against the square root of time in Figure 3.4.10. The plot indicates that this relationship is linear and its slope is a measure of the sorptivity [28]. This type of experiment, coupled with gravimetric measurements, allow for the modeling of... 

Figure 10. Dependence of degradation of pigmented PE sheets (anatase, 0.2% p.v.c.) of different thickness on weathering time, by gravimetric measurement (1)...

The determination of these curves requires not only the measurement of small amounts of heat in a microcalorimeter, but also the simultaneous determination of the corresponding quantity of adsorbed gas. Volumetric measurements are to be preferred to gravimetric measurements for these determinations because it would be very difficult indeed to ensure a good, and reproducible, thermal contact between a sample of adsorbent, hanging from a balance beam, and the inner cell of a heat-flow calorimeter. 

Pinkerton, F.E., B.G. Wicke, C.H. Oik, G.G. Tibbetts, G.P. Meisner, M.S. Meyer, J.F. Herbst, Thermo gravimetric measurement of hydrogen absorption in alkali-modified carbon materials. J. Phys. Chem. 104(40), 9460-9467, 2000. 

Hannaker and Buchanan [82] used a method based on wet oxidation with potassium persulfate [83] for the determination of dissolved organic content in concentrated brines following the removal of inorganic carbonates with phosphoric acid. The method involves wet oxidation with potassium persulfate at 130 °C followed by a hot copper oxidation and gravimetric measurement of the carbon dioxide produced. The technique overcomes difficulties of calibration curvature, catalytic clogging, and instrument fouling often encountered with instrumental methods. 

Figure 6.14. Scheme of the experimental apparatus for gravimetric measurements described by Zavrazhnov et al. (2003) in their investigation of the phase composition control in chemical transport reactions. (1) quartz ampoule, (2) thermocouples, (3) two-zone furnace, (4) quartz rods, (5) wire for suspending the ampoule, (6) support, (7) weighing beam of the analytical balance,... 

Hydrazine sulfate is used as a reducing agent in analytical chemistry for gravimetric measurement of nickel, cobalt, and other metals, and in peptide analysis in the separation of polonium from tellurium as an antioxidant in... 

Fig. 5.4 Amount of adsorbed water on carbon R1 measured by WAXS, compared to gravimetric measurements conducted over a long time period (several months)...

Therefore the elution isotherm should be very similar to the one that results from a static gravimetric measurement. This is shown in Figure 2. ... 

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