CARBON SORBENTS AND THEIR UTILIZATION FOR THE PRECONCENTRATION OF ORGANIC POLLUTANTS IN ENVIRONMENTAL-SAMPLES

This review deals with carbon sorbents and their utilisation to trace analysis of organic pollutants in environmental samples. The first sections are devoted to the general characteristics of various kinds of carbon sorbents, carbon formation, the structure of carbon, their classification and characterisation (activated charcoal, graphitized carbon black, carbon molecular sieves and porous carbon). Information is given on the development of carbonaceous adsorbents, their characteristics and properties, development of various preconcentration techniques, off-line or on-line combination with the analytical measuring system (GC and HPLC), and the application of carbon sorbents to the enrichment of analytes is evaluated. The main use of carbon materials as a preconcentration/preseparation step has been in the sampling and trapping of volatile organic compounds (VOCs) froth air and water matrices. An other field of application is the trapping of semi-volatile and non-volatile -compounds and/or their separation into subclasses. According to the characteristics of the sampled components, carbon sorbents have been utilised in single-bed or multi-bed arrangement (combination of various carbon sorbents or combinations of carbon sorbents with other non-carbonaceous materials) to achieve quantitative trapping of trace components from environmental samples, followed by their desorption for subsequent identification and quantitation. Various achievements and problems, particularly in multicomponent-mixture analysis, are discussed. The physico-chemical properties of recently developed carbon adsorbents are superior compared to those of the "traditional" sorbent materials. Over the recent years much attention has been paid to the application of carbon sorbents for the on-site automated analysis and monitoring of trace pollutants.