[Recent advances in sample preparation technologies for analysis of harmful substances in aquatic products].

Aquatic products, which are among the most important sources of animal protein, contain proteins, vitamins, and a variety of trace elements, thus occupying an indispensable part of a reasonable diet. China is the largest consumer market of aquatic products in the world. The quality and safety of aquatic products are closely related not only to the healthy development of the aquaculture industry, but also to people's health. However, the presence of harmful substances has a bearing on the quality and safety of aquatic products in the overall process, including breeding, processing, storage, and transportation. These harmful substances are enriched in aquatic products and are transferred to humans via the food chain. Accurate determination of such harmful substances in aquatic product samples is imperative because of their complex matrices and extremely low concentrations. Many efficient sample preparation techniques such as liquid-liquid extraction, solid-phase extraction, and QuEChERS (quick, easy, cheap, effective, rugged, and safe method) with different configurations have been developed and widely employed for preconcentration in different matrices of aquatic products. Meanwhile, solid-phase microextraction has been demonstrated to be advantageous for some volatile and ultra-trace harmful substances. Suitable sample preparation techniques are important for effectively removing matrix interferences as well as for improving the sensitivity and accuracy of the method. It is important to develop appropriate sample preparation techniques for different target compounds in aquatic products. The harmful substances in aquatic products can be segregated into three categories according to their sources: (1) environmental pollutants in aquatic products; (2) substances acquired during aquaculture, transportation, and processing; (3) biotoxins in aquatic products. This article reviews the progress in sample pretreatment techniques for three harmful substances in aquatic products over the past decade. Various sample pretreatment techniques have been summarized and described, including liquid-liquid extraction, solid-phase extraction, solid-phase microextraction, QuEChERS, and magnetic solid-phase extraction. In addition, the merits and demerits of these techniques and future research directions are discussed. Finally, we reviewed the progress in functionalized materials for the preparation of aquatic product samples. With the increasing demand for aquatic products, quick, sensitive, and practical detection methods, such as surface-enhanced Raman scattering (SERS) are gaining importance. SERS has great potential for fast and accurate on-site detection of harmful substances in aquatic products. Several nondestructive sample pretreatment techniques have also been developed for harmful substances in aquatic products. The application and development of these techniques will guarantee the safety of aquatic products. Moreover, in vivo solid-phase microextraction is a potential method for aquatic product analysis. This technique integrates sampling, extraction, and enrichment into a single step, thus significantly reducing the processing time, labor, and cost. Overall, with the development and application of sophisticated materials and techniques, we can expect theoretical and practical advances in aquatic product analysis.