Are Hofmeister Series Relevant to Modern Ion-Specific Effects Research?

Authors: Evens, Terence; Niedz, Randall

Submitted to: Scholarly Research Exchange
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2008
Publication Date: 5/5/2008
Citation: Evens, T.J., Niedz, R.P. 2008. Are Hofmeister Series Relevant to Modern Ion-Specific Effects Research?. Scholarly Research Exchange. Volume 2008, Article ID 818461 doi:10.3814/2008/818461.

Interpretive Summary: One of the primary challenges facing agricultural research today is establishing the effects of mineral ions in such wide-ranging disciplines as water quality, plant/animal nutrition, salinity responses, enzymatic processes and the generation of alternative energies. Unfortunately, the traditional approaches to quantifying ion-specific effects have been performed with experimental designs unsuited for this purpose. The use of salts to 'intuit' the effects of ions has led to standard methodologies that are predicated upon a number of unsupported and untested assumptions. This situation is further worsened by a fundamental misunderstanding of the experimental role of several factors, the most important of which is ‘pH’. Finally, there has been an unwarranted focus on single-ion effects, which ignores the more realistic and potentially important, multi-ion blending and interaction effects. We describe the multiple flaws inherent to virtually all such ion-specific experimentation and present an alternative approach that corrects for experimental limitations imposed by the use of salts. In addition, this approach allows researchers to properly quantify the effects of complex ion mixtures and the effects of total ionic concentration, thus capturing the full range of ion-specific experimentation. The concepts and experimental framework described in this manuscript are directly applicable to disciplines ranging from agriculture to human medicine to industrial processing and should result in dramatic improvements in how ion-specific effects and interactions are quantified.

Technical Abstract: Traditionally, the quantification of ion-specific effects has been performed with experimental designs unsuited for this purpose. Designs built using salt-based factors rather than ion-based components are potentially confounded and are predicated upon a number of unsupported and untested assumptions. Ion-based experimentation is further exacerbated by a fundamental misunderstanding of the inherently dependent nature of several factors, the most important of which is ‘pH’. Additionally, there is an unwarranted focus on the generation of single-ion rankings, i.e. ‘Hofmeister series’ that ignores potentially important multi-ion blending and interaction effects. We describe the multiple flaws inherent to virtually all such experimentation and present an alternative approach that corrects for ion confounding and quantifies both the proportional blending properties and the effects of total ionic concentration, thus capturing the full range of ion-specific effects.