The determination of trace metals in mixed matrices

Abstract

Investigations into the determination of < ppb levels of Fe, Pb and Si0 2 in high purity water and Fe and Pb in buffer reagent solution, employed in chemical detector systems, have been carried out by employing the technique of electrothermal atomization - atomic absorption spectrometry (ETA-AAS). Various experimental parameters have been optimized and procedures developed for the relevant determinations. These procedures have been compared and evaluated statistically using F-test and t-test criteria. The preconcentration of Fe and Pb from high purity water using various adsorptive bubble (flotation) techniques (co-precipitation, ion-flotation and solvent sublation) has been studied and various experimental parameters for each technique investigated. The techniques have been compared with the relevant ETA-AAS procedures and the possible use of the flotation techniques for pre-concentration of trace metal ions discussed. Direct-slurry, direct current plasma (DCP) spectrometry, has been studied for possible determination of Cu, Cr and Ag chemical impregnants on activated, granular, carbons used in chemical defence protection systems. Analytical parameters have been investigated and optimized using both aqueous element and carbon slurry solutions. The DCP parameters for the determinations have
been optimized using both Simplex and Univariate search procedures. Results indicated that requisite plasma optima were similar for both aqueous and carbon slurry solutions which showed it to be possible to use aqueous element solutions for calibration of the DCP for carbon slurry analyses. Procedures have been developed and compared statistically with a standard dry ashing/fusion procedure and with a wet oxidation method employing a high pressure asher. Results showed there to be no significant differences between the direct slurry method and the comparison procedures.