Fundamentals, methods and future trends of environmental microwave sample preparation

Microwave (MW) sample preparation has nowadays become a standard analytical tool. A large section of MW systems, such as open vessel and low to high p ressure closed vessel device, are used. Theoretical and practical considera tions in the development as well as implementation of MW sample preparation are presented, including methods for total implementation of MW sample pre paration are presented, including methods for total decomposition and leach ing of trace elements in common environmental samples, such as soil, sludge , sediments, oils, biological materials, water and waste water. In particul ar, the US Environmental Protection Agency Office of Solid Waste methods 30 50B, 3051, 3052 are discussed. Supporting reference data and documentation are presented to demonstrate specific alternative capabilities. As a natura l extension of this technique, MW-based devices were more recently used to heat solvents and sample matrices as a preparation tool for extraction of o rganic compounds. Since 1986 analysts have been using MW heating to extract various compounds from a variety of sample matrices. Information is provid ed about the development of an integrated MW solvent extraction technique a nd its capabilities, as well as perspective for extraction applications. Th e ASTM method D5765-95 on solvent extraction of TPH from soils and sediment as well as the draft of a new US EPA for Volatile Organic Compounds (VOCs) and Semi-Volatile Organic Compounds (SVOCs) from environmental samples are presented. The potential benefits are analogous to those achieved by sampl e decomposition, i.e. reduced reaction/extraction time, improved efficiency , reduced solvent consumption and better working environment. (C) 2000 Else vier Science B.V. All rights reserved.