Table of Contents
Scholarly Research Exchange
Volume 2008, Article ID 818461, 9 pages
Research Article

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

USDA, Agricultural Research Service, U.S. Horticultural Research Laboratory, 2001 South Rock Road, Ft. Pierce, FL 34945-3030, USA

Received 29 February 2008; Revised 17 April 2008; Accepted 5 May 2008

Copyright © 2008 Terence J. Evens and Randall P. Niedz. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Ion-specific effects underlie a vast array of physicochemical and biological phenomena ranging from human physiology to biotechnology to ecology. These effects have traditionally been quantified by measuring the response of interest in a series of salt solutions at multiple concentrations; pH has consistently been shown to be of primary concern. However, salt-based approaches violate critical tenets of proper experimental design and introduce confounding errors that make it impossible to quantify ion-specific effects. For example, pH is a variable dependent on the type and concentration of ions in a solution, but is typically treated as an independent factor, thus confounding experiments designed to determine ion-specific effects. We examined the relevancy of ion-specific effects research in relation to these concepts and demonstrated how these ideas impact protein precipitation and enzyme activity. Based on these results, we present a conceptual and experimental framework of general applicability for proper quantification of ion-specific effects.