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Zastosowanie ekstrakcji wspomaganej promieniowaniem mikrofalowym w kontroli zanieczyszczenia środowiska

Srogi K.

Wiadomości Chemiczne

2006

[Z] 60, 5-6

397-421

The use of microwave energy in sample treatments has attracted growing interest in the past few years. Initially, it was applied to the mineralization of samples. In recent years, numerous applications have reported the use of microwaves for assisting the extraction of organic compounds and organometallic compounds form various environmental matrices. In fact, the use of microwave energy to aid organic extraction was first achieved using conventional household systems in the late 1980s. Thus, in the past few years, numerous compounds have been extracted by microwave-assisted extraction (MAE) from several matrices, with special emphasis on environmental applications. Microwave-assisted extraction (MAE) is a process of using microwave energy to heat solvents in contact with a sample in order to partition analytes from the sample matrix into the solvent. The ability to rapidly heat the sample solvent mixture is inherent to MAE and the main advantage of this technique. By using closed vessels the extraction can be performed at elevated temperatures accelerating the mass transfer of target compounds from the sample matrix. A typical extraction procedure takes 15-30 min and uses small solvent volumes in the range of 10-30 ml. These volumes are about 10 times smaller than volumes used by conventional extraction techniques. In addition, sample throughput is increased as several samples can be extracted simultaneously. In most cases recoveries of analytes and reproducibility are improved compared to conventional techniques, as shown in several applications. This review gives a brief theoretical background of microwave heating and the basic principles of using microwave energy for extraction. It also attempts to summarize all studies performed on closed-vessel MAE until now. The influences of parameters such as solvent choice, solvent volume, temperature, time and matrix characteristics (including water content) are discussed. This article reviews the application of microwave energy to the extraction of organic and organometallic compounds from environmental samples, namely: polychlorinated biphenyls (PCBs), pesticide, phenol, polycyclic aromatic hydrocarbons (PAHs) and dioxins.