ANALYTICAL CHARACTERIZATION OF A CHELATING RESIN COLUMN FOR FIELD PRECONCENTRATION OF TRACE-METALS (CHELEX 100, ION EXCHANGE).

摘要

A rapid preconcentration-preservation sampling system for the routine monitoring of trace metals in natural waters designed to be used in conjunction with the inductively coupled argon plasma (ICAP) for cost effective analysis has been described. The system, consisting of a hand-operated pump, a cartridge type filter unit, and an ion exchange column is simple to operate, lightweight, rugged and otherwise well suited to field application. Due to the fast sampling flow rates attainable with the system, up to 500 mL/minute, samples can be preconcentrated 200 fold in just 10 minutes. Once preconcentrated on the resin column, the trace metals of interest do not require any further preservation treatment simplifying sample transport and storage.; Trace metal preconcentration is accomplished on a 15 mL resin bed of the chelating ion exchange resin CHELEX 100. Column loading and elution parameters have been optimized with respect to maximum analyte recovery from solution under conditions typical of natural waters. Cadmium, copper, lead, manganese, and nickel have been shown to be completely recovered from solution, whereas aluminum recovery has been found to be incomplete. The pH dependent recovery of aluminum has been attributed to incomplete uptake of the dissolved mononuclear and polynuclear hydroxo-complexes present in solution.; Potential interferences from common constituents of natural waters have also been evaluated. Normal sample alkalinity, hardness, and conductivity do not interfere with analyte recovery, however, both fulvic and humic acid inhibit quantitative analyte uptake when present in the sample at sufficient concentrations. To eliminate spectral interference problems with the ICAP a modified procedure for removal of the alkali and alkaline earth elements prior to column elution has been included. Comparison studies conducted on natural water samples have shown good correlation of results with preconcentration by evaporation.