Characterization of soluble and colloidal phase metal complexes in river water by ultrafiltration. A mass-balance approach

Ultrafiltration, anodic stripping voltammetry, and atomic absorption spectrophotometry have been used to determine the distribution and degree of association of major trace metals with discrete size fractions of dissolved organic matter which passes initially through a 0.4-pm membrane filter. A novel mass-balance approach has been developed for fractionation of operationally defined, dissolved organic matter and organometallic complexes into well-defined molecularsize ranges. The highest concentrations of trace metals were found in intermediate molecular weight fractions ( 10^3-10^4) with no detectable free or labile metal as determined by anodic stripping voltammetry.