Water bound total

Mullins [37] has described a procedure for determining the concentrations of dissolved chromium species in seawater. Chromium (III) and chromium (VI) separated by co-precipitation with hydrated iron (III) oxide and total chromium are determined separately by conversion to chromium (VI), extraction with ammonium pyrrolidine diethyl dithiocarbamate into methyl isobutyl ketone, and determination by AAS. The detection limit is 40 ng/1 chromium. The dissolved chromium not amenable to separation and direct extraction is calculated by difference. In waters investigated, total concentrations were relatively high (1-5 xg/l), with chromium (VI) the predominant species in all areas sampled with one exception, where organically bound chromium was the major species. 

The amounts of water associated with various components in a typical reaction mixture are shown in Table 1.2. Most of the water is dissolved in the reaction medium, and the amount of water bound to the enzyme is obviously just a minor fraction of the total amount of water. If the solvent was changed to one able to dissolve considerably more water and the same total amount of water was present in the system, the amount of water bound to the enzyme would decrease considerably and thereby its catalytic activity as well. Changing solvent at fixed water activity would just increase the concentration of water in the solvent and not the amount bound to the enzyme. Comparing enzyme activity at fixed enzyme hydration (fixed water activity) is thus the proper way of studying solvent effects on enzymatic reactions. 

International Standard Organization. 1994. Water quality. Determination of fluoride. Part 2 Determination of inorganically bound total fluoride after digestion and distillation. ISO 10359-2. International Organization for Standardization, Case Postale 56, CH-1211, Geneva 20 Switzerland. 

Where the velocity of the transported quantity is denoted by l], pi is the density, and denotes the transition from phases i and j. From here on, the subscripts w, b, v, and s refer, respectively, to free water, bound water, water vapor, and the solid skeleton of wood. Denoting the total volume by V and the volume of the phase i by Vj, the volumetric fraction of this phase is ... 

Figure 8-2. Quantities of water present in different phases when solvents are compared at equal total water content or equal water activity. The behavior of the enzyme is likely to depend only on the amount of water bound to it.

Lead appears to be able to interact with complex small biomolecules as well, such as flavins for example, bis(lO-methylisoalloxazine) perchlorate tetrahy-drate (223). IsoaUoxazine is a planar three-ringed heterocychc amino cofactor associated with riboflavin and is active in oxidation-reduction reactions with metals such as Mo and Fe. Lead binds to bis(lO-methylisoalloxazine) in a 1 1 metal-ligand complex, with two additional waters bound resulting in a four coordinate molecule with a total of four oxygen donors. An active lone pair results in a distorted square-pyramidal structure. As is the case for citrate, extensive hydrogen bonding was observed in the crystal lattice. 

Figure 34 Ratio of bound water-to-total water content (volume of bound water divided by volume of total water) vs. water content. (From Ref. 141. With permission from Elsevier Science.)...

PEMs lEC (mmolg" Water )uptake (%) Total Non- freezable water Loosely bound water Free water a (Scm )... 

Total water = (Water bound to the enzyme) + (Water dissolved in the solvent) [14.4.3.1]... 

The sorption isotherm will than be the sorption isotherm of amorphous cellulose, intimately connected with its swelling. The total amount of water bound at a given pressure and the total heat given out upon complete wetting (integral heat of sorption), will be proportional to the amount of amorphous fibre substance. 

From the point of view of water analysis, "total cyanides" include all those compounds which - in contrast to the "easily decomposed" cyanide compounds - can release even very firmly bound (complexed) cyanide under the right conditions, such as those provided by decomposition distillation in a highly acid environment. 

The water in coal is bound in different forms to its constituents. It can be divided into three types (1) Free moisture, also referred to as external moisture, superficial moisture, or the primary moisture fraction, which is present in large cracks and capillaries. Water bound in this way retains its normal physical properties. (2) Inherent moisture, also referred to as internal moisture or the secondary moisture fraction, whose vapor pressure is lower, since it is absorbed within the pore structure of the coal. (3) Water of constitution, which is mainly combined with mineral matter normally present in coal. This water is generally driven off only at temperatures higher than those normally used for the determination of moisture content. Standard methods do not make use of these terms and define (1) the total moisture content of a coal and (2) the moisture content of the coal analysis sample. Total moisture determination must be made over the sample as received in the laboratory, in an air-proof recipient. The determination consists in drying in an oven at 105 °C till constant weight. Its value is of huge interest both in international and domestic coal trade (ISO 589, ASTM D3173). 

All bound water unfrozen at F<273 K can be assigned to strongly associated water at 8h 5-5.5 ppm. WAW at 5h=1-2 ppm is not observed in any of the studied suspensions of the initial nanooxides. The total amounts of water bound by oxide nanoparticles in these suspensions (Table 2.8 Cuw = Cuw + C"w = lFp.5g/g at a major contribution of weakly bound water frozen at F>260 K Figure 2.40a) are much larger than that observed from the measurements of the water... 

Figure 2.65 shows typical H NMR spectra of unfrozen water bound in wetted powder (total amount of water h=0. gig) and aqueous suspension [C =90 wt%] of SA8 (as a representative sample) recorded at different temperatures. 

Under the experimental conditions and due to the short time of transverse relaxation of proton in solids, the contribution of protons from ice and surface hydroxyls to the recorded NMR signal can be neglected. Only the signal from mobile water molecules remaining unfrozen (due to the interaction with the carbon surface or solute molecules and ions) at temperature below 273 K was measured. The amount of unfrozen water bound to carbon surface and protein molecules is temperature-dependent. It was determined from the ratio of signal intensities before and after freezing using a special calibrated function. The total amount of water in each sample was constant (2 mL). 

The effects of the aqueous suspension of fumed silica A-300 onto water bound in bone tissue of the M37 sample are close to that of pure aqueous medium (Table 7.14). Silica surface is strongly hydrated (Strange et al. 2003, Gun ko et al. 2005d) however, the total amount of water bound to this surface is smaller than that bound in bone tissue. Perhaps, penetration of silica nanoparticles into narrow pores of the studied spongy component of bone tissue (where major amounts of structured water locate) does not occur therefore, silica particles being out (or in macropores) of bone tissue are not capable to affect water locating in bone tissue. An increase in the S value by 21% with the presence of silica is due to its high specific surface area. 

The main difference in the properties of water bound in spongy component of healthy bone and bone affected by osteoporosis is linked to the concentrations of WAW and SAW (Figure 7.58) because of the structural differences in the mineral matrix of these samples (Figure 7.61). In the aqueous medium, the maximum amount of bound water is equal to 900 mg/g for M37 and 1300 mg/g for M61. The greater amounts of water adsorbed onto bone tissues affected by osteoporosis are due to the formation of larger pores (Figure 7.61) and lower density of this bone tissue. The increase in the total amounts of bound water in the aqueous medium causes an increase in concentration of the SAW and contribution of unusual (interstitial Wilson et al. 2005b) water with the chemical shift at 8h= 1.3 ppm decreases. 

---