Growth in economics and prosperity has been a global trend during recent decades and the use of chemicals has increased tremendously as a part of industrial production, agriculture and everyday life. The use of hazardous chemicals has been restricted by many intergovernmental treaties and legislation but new replacement chemicals are synthesized constantly and no decrease in the future production volumes of chemicals is soon expected.
The term chemicalization is used to describe the increased use of chemicals and resultant environmental contamination. In the analysis of environmental samples, usually only some selected regulated compounds are measured. The problem with these target analyses is that other compounds remain undetected. Complementary techniques without any preselection of the analytes are thus required to identify new compounds.
The aim of this study was to develop novel instrumental techniques for the determina-tion of organic compounds without any analyte preselection and to identify unknown anthropogenic contaminants in different water matrices. The methods developed were based on analytical separation, using gas and liquid chromatography combined with accurate mass measurement using time-of-flight mass spectrometry.
The data produced were then processed with a deconvolution program to locate the chromatographic peaks and to extract their mass spectra. The measured accurate masses were then used to confirm the elemental compositions of the detected ions. The identification processes were validated, using spiked water samples, and finally the methods were applied to the identification of organic xenobiotics from wastewater effluent, stormwater, surface water and landfill leachate samples.
The results showed that analysis using time-of-flight mass spectrometry enables screening of large analyte groups without previous information on sample composition. The most comprehensive knowledge is yielded by analysing the sample with both gas and liquid chromatography. In many cases, tentative compound identification can be obtained if the deconvoluted spectra and accurate mass data are complemented with information, e.g. from spectral libraries and peak isotope patterns. This tentative identifications must, however, always be confirmed with a pure standard compound.
The main limitations of the methods were related to insufficient features of the deconvolution program used. Most of the data-processing stages had to be performed manually or visually, which slows down the data processing and hinders their applicability, especially with large sample sets. Dozens of compounds were tentatively identified from water samples and several of them were also confirmed with a standard compound. The highest numbers of compounds were identified from wastewater effluent, stormwater and landfill leachate samples. The results confirmed the fact that anthropogenic waste streams are an important route for organic xenobiotics into the environment. Since the future volumes of chemicals will increase, the control and efficient treatment of these fluxes becomes evermore essential.