Metal-ion content

However, as soon as at the eluate-side H ions are replaced with an equivalent amount of Na or K ions, which elute, the then asymmetric cell acquires a potential that reflects the Donnan equilibrium potential on the basis of the ion mobilities concerned. Hence the potential change as a function of time represents the ionic chromatogram and the peaks concerned yield the alkali metal ion contents via calibration. 

Table 10.13 Metal ion content of six different cotton samples obtained by atomic absorption studies [236]...

To start our approach we divide this chapter into parts. In the first part we outline the general chemical element content of all organisms (Sections 4.2-4.4) next, we look at the uses of non-metal elements and their in small molecule combinations (Sections 4.5 1.8) while in the third part we extend this description to their major biopolymers (Sections 4.9-4.13). Section 4.14 is a summary of these sections. In Sections 4.15 and 4.16 we examine the metal ion content of cells and combinations of these ions with organic molecules. The final sections integrate these descriptions with those of the principles of bioenergetics outlined in Chapter 3. 

Table II. Metal Ion Content (ppm) of Cottonwood and Acid-washed Cottonwood...

The many tyrosinases in nature differ in cofactor requirement, metal ion content, substrate specificity, molecular weight, and oligomeric structure. The diverse properties of the tyrosinases will not be discussed instead, the properties of a single enzyme, mushroom tyrosinase, will be outlined. 

Water quality (metal-ion content) may be responsible for shifts in shade. Sequestrants are used as a safety measure. 

There are a number of alternative approaches to lability measurements, and three which involve different timescales are listed in Table 2.8. The level of labile electro-active metal species present in aqueous samples can be determined using ASV (see Section 2.7.4). The electrochemical response (i.e. peak area values) reflects the hydrated metal ion content together with contributions from any metal complexes present which rapidly dissociate in the diffusion layer (around the mercury cathode). The labile metal is measured either at the natural sample pH, or after pH adjustment (e.g. after addition of pH 5 acetate buffer). 

The electro-chemical response (i.e. peak area values) reflects the hydrated metal ion content, and contributions from any labile complexes present. The size of the peak can be affected by experimental parameters such as the deposition potential used, the rate of stirring, the mercury drop diameter, the pulse frequency, the stripping solution composition, the system pH and the temperature. The size and position of the ASV peak can also be influenced by the chemical nature of the original test sample through processes such as... 

Visual inspection and the results of metal ion content in water samples, shows internal pipe corrosion in various locations in the hot water distribution system that compromises the quality of hot water. The cause of the internal pipe corrosion can be attributed to the following factors or a combination of the factors. 

According to a recent report by Hultberg (1983), toxicity in aquatic systems is due not only to direct action of the low pH of the water and to the increase of metal ion content but also to the change of the carbon source from HCOs" to CO2. This may influence the retention of phosphorous in soils by alluminium precipitation. This indicates substantial modification in the ecological equilibria in the aquatic system. 

Literature reports that indigenous metal ions can be removed from coal char by acid washing. In order to lower the metal ion content in our charcoal, we stirred some charcoal in an aqueous HCl solution (18 wt.-%) for 52 h, filtered and dried it. The metal removal efficiency was checked by metal content analysis which is discussed further down in the text. 

The data show that the transition metal ion contents of (S)ZSM—5 and (L)ZSM-5 differ significantly, the (S)ZSM-5 samples containing much more transition metal ion than required for 100% ion-exchange. Apart from Cu(S)ZSM-5, therefore these samples are regarded as "over-exchanged" materials. 

McBride, M. B. (1980b). Influence of pH and metal ion content on vanadyl ion fulvic acid interactions. Can. J. Soil Sci. 60, 145-149. 

Sorption samples were prepared for XAS using the same procedures described above for generating the pH edges and isotherm data. All samples were equilibrated for a minimum of 24 h prior to pH measurement and centrifugation. An aliquot of supernatant was then removed and stored in acid prior to subsequent analysis for metal ion content. Most of the remaining supernatant solution was then removed and the remaining wet pastes were placed into aluminum sample holders, sealed with mylar or Kapton tape windows for XAS analysis. 

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