[Progress of sample preparation and analytical methods of dried fruit foods].

Dried fruit foods, including nuts and preserved fruits, are favored by consumers and are rich in protein, lipids, minerals, vitamins, and other nutrients. However, these food products can be contaminated by pesticide residues, heavy metals, mycotoxins, and additives during growth, processing, storage, and transportation. The presence of such pollutants in excess of a certain limit will lead to food safety problems. Therefore, it is of great economic and social significance to strengthen the quality supervision of dried fruit foods. However, these foods have a complex matrix and low concentrations of various harmful substances, which necessitates efficient and appropriate sample preparation methods as well as rapid, accurate detection methods. In the present article, the sample preparation and analytical methods for harmful substances in dried fruit foods since 2010 are reviewed. The sample preparation methods are classified as field-assisted extraction, phase separation, and derivatization and extraction methods. The field-assisted extraction method is based on the action of an external field (synergistic) such as ultrasonic or microwave fields to increase the dissolution rate of hazardous substances in dried fruits and improve the extraction efficiency. Phase separation methods such as solid-phase extraction, dispersive solid-phase extraction and solid-phase microextraction are commonly used as sample preparation methods for dried fruit samples, because of the advantages of low solvent consumption and wide analysis range. Moreover, this paper discusses the progress of various analytical methods for these hazardous substances in dried fruits, including conventional laboratory methods such as chromatography, atomic spectroscopy, inorganic mass spectrometry, and electrochemical analysis, as well as rapid detection techniques suitable for field analysis. Laboratory testing has the advantages of high accuracy, high sensitivity, and low detection limits. However, it has the disadvantages of complicated preparation, long analysis time, and difficult operation. Rapid detection technology speeds up the analytical speed, has operational simplicity, and saves analysis time. The complexity of the food matrix, which easily interferes with the sample matrix, low selectivity, and difficulty in accurate quantification, it is necessary to minimize cases of incorrect or erroneous detection. Therefore, rapid detection of harmful substances in dried fruit foods is possible by optimizing the sample pretreatment methods and detection technologies, and by seeking new (especially, on-site) detection technologies. Prospects on the development of selective and non-destructive sample preparation methods and automated, high-throughput, rapid detection methods in dried fruit food analysis are presented. The development of new, green rapid sample pretreatment methods and technical products that integrate separation, enrichment, and detection as well as the construction of accurate and sensitive rapid detection methods are expected to become the development trend in the analysis of harmful substances in dried fruit foods.