Metal ions tolerance limits

The tolerance limits of metal ions and foreign anions at the optimal conditions were investigated. 

The strategy of wort supplementation with metal ions, lipids and yeast foods , with the aim to improve fermentation performance, is reviewed in detail by Gibson (2011). Among metal ions, zinc and magnesium were identified as elements with a crucial role in wort fermentation, the supplementation of which led to reduced attenuation time (Zn, Mg), increased uptake of trisaccharides (Zn) and increased ethanol production (Zn) and tolerance (Mg). It was also found that zinc has an indirect effect on the synthesis of higher alcohols and esters as well as on foam properties. Calcium supplementation of wort may only be beneficial when Ca concentration is limited in the local water supply (Gibson, 2011). 

For a range of simple substitutional solid solutions to form, certain requirements must be met. First, the ions that replace each other must be isovalent. If this were not the case, other structural changes (e.g., vacancies or interstitials) would be required to maintain electroneutrality. Second, the ions that replace each other must be fairly similar in size. From a review of the experimental results on metal alloy formation, it has been suggested that 15% size difference can be tolerated for the formation of a substantial range of substitutional solid solutions. For solid solutions in nomnetal-lic systems, the limiting difference in size appears to be somewhat larger than 15%, although it is very difficult to quantify this. To a certain extent, this is because it is difficult to quantify the sizes of the ions themselves, but also because solid solution formation is very temperature dependent. 

Since the publication of the third edition in 2004, considerable effort has been focused on the development of monolithic separation materials for use in ion chromatography. Monolithic media offer the potential benefit of faster analysis or improved resolution with comparable analysis speed, thus following the trend toward shorter analysis times observed in conventional liquid chromatography. While method speedup in conventional liquid chromatography (UHPLC) is achieved by utilizing smaller particle sizes and smaller column formats, this pathway can be followed only to a certain extent in ion chromatography due to the limited back pressure tolerance of metal-free components in the fluidic... 

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