Analytical methodology for the determination of aluminium fractions in natural fresh waters (technical report)

The distribution among different species, ''speciation'', is essential for understanding the toxicity, bioavailability and transport mechanisms for elements in the natural environment. The distribution of Al among different species has been in focus during the last twenty years or so, and many methods for fractionating Al have been developed. Most of them are operationally defined, since validation of what is really measured in natural systems is very difficult. This review is a thorough and critical survey of the existing methods for Al fractionation in natural waters, that covers the literature up to and including June, 1994. The methods have been classified into six groups, according to the principles used: 1) Kinetic or Binding Strength Discriminations; 2) Ion Chromatographic Separations; 3) Size Exclusion; 4) Non-Invasive Methods; 5) Ion Mobility in an Electric Field; 6) Minimized Disturbance. In addition to this, in order to validate the different techniques, we scrutinize some of the method comparisons published.