Deuterium oxide volume

Several compounds have been proposed for the measurement of the void volume, including sodium nitrate solution, water, deuterium oxide, fructose, acetonitrile, tetrahydrofuran (THF), meso-erythritol, gluconolactone, and 2,4-dinitronaphthol. The elution volume of a number of these compounds has been measured in 10-90% aqueous acetonitrile and acidic-aqueous acetonitrile. The results are given in Figure 3.9 where the volumes in A and B were measured in aqueous acetonitrile and in C and D were measured in aqueous acetonitrile containing 50 mM phosphoric acid. Methanol (a) and deuterium oxide (g) showed two peaks when monitored by a refractive index detector (Figure 3.9C). 

Figure 3.9 Elution volumes (ml) of alternative void volume markers. Column, 5 im octadecyl-bonded silica gel, 15 cm x 4.5 mm i.d. eluents A and B, 10-90% aqueous acetonitrile, eluents C and D, 10-90% aqueous acetonitrile containing 50 mMphosphoric acid flow rate, 1 ml min temperature, 30 °C detection, UV 210 nm and refractometer. Sample a, acetonitrile b, methanol c, fructose d, 2,4-dinitronaphthol e, sodium nitrate, f, tetrahydrofuran g, deuterium oxide, and h, uric acid.

In view of Freeman s studies on the use of normal alkanes and polystyrenes to probe the macroporosity of porous materials (24), the results presented here would suggest that low molecular weight species ranging from twenty (deuterium oxide) to several thousand daltons may be used to define microporosity of a SBC support. The ease with which this is achieved may allow routine examination of microporosity in new support materials and a more exact definition of total permeation volume in SBC. 

To dearly distinguish between these two modes of solvent penetration of the gel, we immersed poly(acrylamide-co-sodium methacrylate) gels swollen with water and equilibrated with either pH 4.0 HQ or pH 9.2 NaOH solution into limited volumes of solutions of 10 wt % deuterium oxide (DzO) in water at the same pHs. By measuring the decline in density of the solution with time using a densitometer, we extracted the diffusion coefficient of D20 into the gel using a least squares curve fit of the exact solution for this diffusion problem to the data [121,149]. The curve fit in each case was excellent, and the diffusion coefficients obtained were 2.3 x 10 5cm2/s into the ionized pH 9.2 gel and 2.4 x 10 5 cm2/s into the nonionized pH 4.0 gel. These compare favorably with the self diffusion coefficient of D20, which is 2.6 x 10 5 cm2/s, since the presence of the polymer can be expected to reduce the diffusion coefficient about 10% in these cases [150], In short, these experiments show that individual solvent molecules can rapidly redistribute between the solution and the gel by a Fickian diffusion process with diffusion coefficients slightly less than in the free solution. 

The direct coupling of liquid chromatography with proton NMR has been attempted numerous times. Early experiments of coupled HPLC- H-NMR were conducted in a stop-flow mode or with very low flow rates [193-195]. This was necessary to accumulate a sufficient number of spectra per sample volume in order to improve the signal-to-noise ratio. Other problems associated with the implementation of on-line HPLC-NMR have included the need for deuterated solvents. However, with the exception of deuterium oxide, the use of deuterated eluents is too expensive for routine analysis. Therefore, proton-containing solvents, such as acetonitrile or methanol, must be used. To get rid of the solvent signals in the spectra, the proton NMR signals of the solvents have to be suppressed. 

D4]Malonic acid Carbon suboxide (6.3 ml) is distilled into a graduated tube that is cooled to —78°. Deuterium oxide (1 g), placed in a Pyrex tube (1.5 x 25 cm), is also cooled to —78°. An equivalent amount of the carbon suboxide (measured by the diminution in volume in the graduated tube Pyrex tube, and carefully dried benzene (10 ml) is added. The tube is then closed and shaken for several days at room temperature, after which it is opened and the crystalline malonic acid is filtered off, washed with benzene, and dried over P205. It melts at 128-130°, and the yield is almost quantitative. 

Samples need to be redissolved for solution P NMR, with the final volume determined by the size of the NMR probe. For a 10-mm probe (the most common size used for environmental P NMR), the final volume should be 2-3 ml, and the sample should not be too viscous, to prevent line broadening from spin-spin coupling. Samples may be redissolved in water, sodium deuteroxide (e.g. Sumann et al., 1998), deuterium oxide plus sodium hydroxide (e.g. 

Preiss et al. [81] reported the use of stopped-flow HPLC-NMR to identify dyes and other pollutants in the effluent from a textile manufacturing plant They utilized a mobile phase of gradient of acetonitrile and deuterium oxide. Although they used conventional volume equipment, stop-flow times of 0 min to 2 h were required to achieve good S/N for individual components. They identified 14 dyes, their degradation products, or other compounds (such as long-chain benzenesulfo-nates). 

Let us now look into the basic characteristics of the freezing/melting process of water. Under normal conditions (and probably in the presence of impurities), bulk water fijeezes into a hexagonal lattice with a release of 1.44 kcal/mol of latent heat This is accompanied by an increase of volume, as mentioned earher, of 8%. Water also has a variety where two hydrogen atoms can be replaced by deuterium. This is called deuterium oxide or heavy water (D2O). It has physical properties similar to normal water Avith some modification due to the isotope effect In the case of heavy... 

Validation of body water measurements, using dilution principles and either of the hydrogen isotopes, can only be achieved from complementary desiccation studies. In fact it has been repeatedly demonstrated in animals that the volume of dilution of deuterium oxide corresponds closely to the total body water space [249—252]. A single report has suggested that the difference between isotope dilution using tritium and desiccation, was statistically significant in the rat and that the former method overestimated body water by 12% of the desiccation value [253]. 

In an unusual study, H n.m.r. was used in the detection and analysis of pressure-dependent changes in polylAf -(3-hydroxypropyl)-L-glutamine) in water-deuterium oxide. Increased pressure appeared to induce volume changes associated with transition from helix to random coil, resulting in the exposure of hydrophobic groups to solvent. 

Triatomic Gases.—Kell et al measured mass, p, and T of water vapour in a nearly constant volume for various temperatures between 150 and 450 C, and pressures in the range 0.6 to 94 bar. They calculated B, C, and A and expressed B and C as functions of T. The same workers carried out a similar study of deuterium oxide vapour, the range of variables being 150 to 500 °C and 1.0 to 101 bar. They calculated B and C, and showed that B for D2O is very slightly more negative than B for HgO. 

The unsaturated ester (0.5 mmole) is dissolved in anhydrous dioxane (5 mL) at room temperature, and deuterohydrazine (5 mmole) in twice its volume of deuterium oxide is added. The mixture is stirred at 55-60 C in air, but in the absence of atmospheric moisture, for 8 hr when the reagents are evaporated in vacuo. The product is purified by preparative silver ion chromatography (see Chapter 6)". 

Angyal s group has reported a detailed n.m.r. study of the tautomeric equilibria of the 2-hexuloses and some of their derivatives in aqueous solution -all the resonances in the n.m.r. spectra were assigned with the aid of specifically deuteriated compounds. The proportions of the anomeric furanoses and pyranoses present in solutions of the 2-hexuloses at equilibrium in deuterium oxide at 27 °C are shown in the Table (cf. Volume 8, p. 172), and the results were discussed in terms of conformational analysis. 

It is not easy to see how the first of these criteria could be applied to two-phase catalysis. The rate of the catalysed reaction depends upon the volume of the resin phase (for constant chemical composition of the resin) and hence on the total amount of catalyst per unit volume of suspension, quite irrespective of mechanism and even when the catalyst is a strong acid and catalysis is simply due to the higher concentration of hydrogen ions in the resin phase. The second criterion is, in principle, applicable, as discussed in the next section, but is complicated by the lack of an entirely satisfactory quantitative theory of the dissociation of poly-acids [38, 48, 50]. It should be possible to make some use of the third criterion, based on the solvent change to deuterium oxide. 

Lejeek, R Matous, J. Novak, J. R Rick, J. Rhase equilibria and excess molar volumes of tetrahydrofuran (1) + deuterium oxide (2). J. Chem. Thermodyn. 1975, 7, 927-935. 

The infrared spectra were recorded on a Perkin-Elmer model 237 grating spectrometer. Alkali halide and silver chloride cell windows were used with appropriate Teflon spacers to obtain comparable band intensities from several concentrations of PEO in benzene and deuterium oxide. A variable path cell was used in the reference beam to compensate for solvent absorption in the spectra of benzene solutions with low concentrations of PEO. Deuterium oxide was used instead of water as a solvent because, in the spectral regions of interest, it contributed less back-ground absorption. All solution compositions are given in volume per cent. 

The study of hydrogen and deuterium electrosorption in palladium limited volume electrodes (LVE) was carried out by the same group in both acidic and basic solutions [124,130,134]. It was found that the hydrogen capacity, H (D)/Pd, measured electrochemically, depends significantly on sweep rate in cyclic voltammetric experiments and also on the thickness of the LVE. Two different mechanisms of hydrogen desorption, that is, the electrochemical oxidation and the nonelectrochemical recombination step, which take place in parallel within the Pd—LVE, have been postulated. 

Figure 3.21. A dynamic SIMS depth profile showing the volume fraction of a polystyrene of relative molecular mass 29000, with both ends carboxy terminated, in a matrix of deuterium-labelled, normally terminated polystyrene of relative molecular mass 500000, after annealing at 160 °C for 36 h. The volume fraction, derived from the intensity of the CH ion, is measured as a function of the distance from the substrate, which is a native-oxide-coated silicon wafer. After Zhao et al. (1991).

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