Thermal desorption and atomic emission spectrometric determination of adsorbable organically bound elements for water analysis†

Abstract

A new analytical method and system has been developed which can be used for the simultaneous determination of adsorbable organically bound elements (AOE) contained in a water sample. This new method of water analysis, by summary detection of substance categories, will significantly extend the existing water parameter for adsorbable organically bound halides (AOX). The organic water impurities are separated quantitatively along the lines of German standards DIN 38409, H14 through adsorption on activated charcoal. Simultaneous element-specific detection can then be carried out by plasma emission spectrometry. As a special innovation, the new method allows the use of highly sensitive plasma types (e.g., microwave-induced plasma) through thermal desorption of the analyte compounds because no interfering CO₂ is generated. Here other sorbents of the kind needed for other problematic separation processes can also be used. The system is equipped with the possibility of removing gases containing solvent vapours. Compared with the conventional method, the thermal desorption step has no influence on the sensitivity or the precision of the determination of adsorbable organic model substances. The first calibration of the new system resulted in a detection limit of 0.20 µg of chlorine.