Hofmeister ion series

The ion series gained by change of water spectra determined by Tstr is similar to the lyotropic ion series or so called Hofmeister ion series according to these observations. The cause of the lyotropic ion series is identified as an effect on the water structure. The salt series in the order of changing the water spectra is ... 

Negative values ofN —N0, the electrolyte effect on the association numbers of water, are called the structure-breaker effect. One can speak of negative hydration31. The estimation of the hydration numbers by spectroscopic or solubility methods gives only an approximation of the sum effect. The spectra of the H-bond bands show in second approximation distinct differences between the ion effects on the H-bonds7 ). — The partial molar volume Vx of water in electrolyte solutions is negative in all solutions but the series of -values corresponds to the Hofmeister ion series too. The negative V1 volume indicates an electrostriction effect around the ions. 

The dependence of /fmoi on the salt concentration varies a little with the salt s type. Therefore, this salt series varies a little with G. The influence of the different ions to K corresponds to the Hofmeister ion-series or the ion-series got by the influence of the water structure31,72 ... 

It has been remarked that the ion effects on the stability of proteins are caused by interactions or bindings of the ions to the polymers181 215,220 221 But this seems to be very improbable, because the ion series is mainly the Hofmeister ion series. We have shown that the Hofmeister ion series is the series influencing the water structure (see Chapter II a). In addition the similar ion series obtained with very different polymers or oligomers is a second point in favour of the change of the water structure. This can be substantiated by comparing our very different experiments with polyethylenoxide products. 

The rejection of anions by cellulose acetate membranes is a mirror of the Hofmeister ion series again242 ) Citrate > tartrate > SO4 " > Ac" > Cl" > Br" >... 

The Hofmeister ion series gives the order in which changes occur in water structure. The positions in this series denote specific effects, one parameter being the ion size ( ) ... 

The interactions of equations 3 and 6 may be smaller or bigger than in 1. The structure of electrolyte solutions depends therefore in Hofmeister ion series on the specific ion-water interaction, on the coordination numbers and on the concentration if the hydration spheres are large enough to disturb each other. 

There eire a lot of salt effects on biological samples, which can be ordered by the Hofmeister ion series (10). All these effects indicate changes of the water structure and its importance for living cells. 

The Hofmeister lyotropic series can be used to select an anionic (F > Cr > Br > 1 > NO3) or cationic (Al > Mg > Ca > Na > K+ > NH ) species, where the precipitation ability is related to the hydration of the ion and its ability to separate water molecules from the hydrophilic regions of the molecule. Overall, anions hydrate more strongly than cations for the same ionic radius because they can approach closer to the hydrogen atoms when compared to the oxygen atoms, respectively (Grossfield et al., 2003). Anions are also usually more polarizable than cations due to their diffuse extra electrons (Kropman and Bakker, 2001). 

On the other hand, despite the information about long chain sulfates, sulfonates, phosphates, and carboxylates that indicates stronger interaction with Ca2+ than with Mg2+ (i.e., in apparent harmony with the sequence of the Hofmeister (44) series), several difficulties remain. For example, while Miyamoto s data for DS (10) indicate the interaction sequence Mg < Ca < Sr < Ba from solubility measurements (as well as from temperature/CMC measurements if one accepts the Mg—Ca sequence of the present paper), this sequence, with the exception of the position of Mg and Ca, is the opposite of that found by Deamer et al. (33) from condensation effects on the force/area curves of ionized fatty acids. At the same time, the ion sequence obtained by these authors from phase transition temperatures of spread fatty acids (33) differs from that deduced from the above-mentioned condensation effects, and the latter depended strongly on pH. Lastly, definite differences in ion sequence effects exist for the alkaline earth metals in their interaction with long... 

Prague together with some colleagues and students [5]. He was essentially interested in physiological effects of salts. For example, he studied the influence of salts on protein precipitation and on swelling processes. From this work the so-called Hofmeister series was deduced. It should be mentioned that Hofmeister only made classifications of entire salts and not of separate ions. Such ion series were introduced much later, for example, by Voet and Pearson [6,7], based on the lyotropic series and classifications according to the softness and hardness. ... 

With the help of selectivity coefficients, such as in Eqs. (4.51) and (4.52) a general order of affinity can be given. For most clays the Hofmeister series (the same series as was given in Eq. (2.17) for the affinity of ions to oxide surfaces)... 

A number of studies have reported the abilities of different eluting salts to produce both different resolution and different selectivities.17 23 As expected, polyvalent ions are stronger eluters than monovalent ions. Some studies have suggested a correlation between eluting ability and ranking in the Hofmeister series. Others fail to observe this correlation, but nevertheless note differences in elution behavior. Overall, it is impossible to predict which eluting ions, if any, may produce a... 

An empirically derived relationships that describes the systematic effects of different neutral salts on the solubility of proteins. Collins and Washabaugh indicate that the order of ionic species eluding from a Sephadex G-10 column corresponds to the known order of effectiveness ions in the Hofmeister series on protein solubility ... 

Substances destroying the water structure, fhe so-called chao-tropic substances such as urea, guanidinium hydrochlorid, or some organic solvents such as mefhanol, efhanol, or acetonitrile, suppress hydrophobic interactions. Ions also alter the water structure. The power of destruction of water structure is given by the Hofmeister series ... 

Differences in both the charge density and the hydration of ions determine the Hofmeister series (lyotropic series).91... 

Figure 8.6 Hofmeister series of kosmotropic and chaotropic ions.

K. D. Collins. Ions from the Hofmeister series and osmolytes Effects on proteins in solution and in the crystallization process. Methods, 34(3) 300-311, 2004. 

In considering the differential or selective binding of one anion or another, the intrinsic properties of anions mean that we are not on a level playing field it is considerably easier to bind some anions than others. In general, in the absence of specific chemical recognition between anion and host, anion binding selectivity, particularly in solvent extraction experiments or in the detection of anions by membrane-based ion selective electrodes, follows the order of anion hydrophobicity. This order is termed the Hofmeister series, or lyotropic series and was first outlined in 1888 from experiments based on the... 

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