The Progress of Pretreated Methods and Its Extraction Materials for Polychlorinated Biphenyls in Environmental Samples

Polychlorinated biphenyls (PCBs) are importantly strong carcinogenic persistent organic pollutants, and their concentrations are very low (10^-9-10^-8 mg/kg) in environmental samples, such as in water or sediment samples. It is very important to select appropriate pre-treatment methods to achieve the separation and enrichment of trace PCBs in complex environmental samples, which is important for the speciation and toxicity study of PCBs. The development direction of the pretreated method for PCBs includes application of green pre-treatment technology, reduction of organic reagents usage, simplification of the chemical procedure, improvement the enrichment and separation effect, and decreasing the background interference. In recent years, substantial progress has been made in pre-treated methods for PCBs and the new developed extraction material is the key for pretreated methods. This paper demonstrates an overview of the main pre-treated methods for PCBs such as liquid-liquid extraction, supercritical fluid extraction, microwave extraction, accelerated fluid extraction and solid-phase extraction. Solid-phase extraction is one of the best methods to enrich PCBs. The different materials for solid-phase extraction have the advantages and defects for the effects of PCBs enrichment and operation. The application of newly developing magnetic solid extraction nanometre materials, which has extremely high specific surface area and better absorbability, reduces the pre-treatment time compared with the traditional solid-phase extraction method. The molecularly imprinted extraction nanometre material has high enrichment and selectivity which reduce the background interference and is better suited to extract low level PCBs. The magnetic solid extraction nanometre material and molecularly imprinted extraction nanometre material are the main research direction for the future.