# Application of Sorbent-Based Extraction Techniques in Food Analysis
## 3 SPE in Food Analysis--Main Fields of Applications
### Mycotoxins  
Recently, the presence of mycotoxin contamination in food, considering both adverse effects on human health and economic losses resulting from spoiled products, has received attention worldwide [35]. Mycotoxins occur as native contamination in food matrices, and they can be synthesized by numerous fungal species before crop harvest, or during the storage process in poorly preserved food. The consumption of plant- or animal-originated products which contain mycotoxin contaminations can lead to serious diseases (headaches, abdominal ache, diarrhea, vomiting) or even increase the risk of cancer development due to the carcinogenic, mutagenic and teratogenic properties of mycotoxins [36]. Therefore, reliable mycotoxin analysis methods are necessary. The determination of mycotoxins in food usually relies on three main detection methods--HPLC with fluorescence detection, diode array detection (DAD) or tandem MS. Capillary electrophoresis, colorimetric detection, enzyme-linked immunosorbent assay (ELISA), GC, and thin-layer chromatography form a group of analytical approaches that are less frequently used. In any case, the key stage in the analysis of mycotoxins is the sample preparation process. Various techniques have been utilized so far like LLE, immune-ultrafiltration, pressurized liquid extraction, dispersive liquid-liquid microextraction (DLLME), and QuEChERS. SPE, applied individually or in combination with previously mentioned procedures, is commonly used as a regular method of mycotoxin extraction [37]. Microwave-assisted extraction utilizes microwave energy to increase the efficiency of rapid heating of organic solvents which interact with the sample in the base of the partition coefficient of the desired analyte. Although this method has many advantages (fast, more environmentally friendly due to cut-off organic solvents, higher extraction yield), SPE must be applied as an enrichment stage [38]. Ochratoxins belong to the class of toxins that are synthesized by heterotrophic fungi belonging to the genera _Aspergillus_ and _Penicillium_ (_Penicillium verrucosum_, _Aspergillus ochraceus_ and _A. niger_, _A. carbonarius_.) [39]. These carcinogenic, immunotoxic, nephrotoxic and teratogenic compounds have been detected in food of animal origin, especially in pork and poultry, and are able to accumulate in the kidneys, liver, pancreas, and blood. At lower concentrations, mycotoxins have been observed in muscles, adipose tissue, and eggs, which makes the clean-up procedure considering the complexity of these tissues/fluids very complex. SPE with C18 columns method was used as a purification step followedby LC-MS/MS, enabling rapid determination of ochratoxins with high selectivity and specificity in animal tissues and other matrices [40]. The _Aspergillus_ genus is an example of a fungal species which produces toxic secondary metabolites called aflat. Aflatoxin B1 is considered the most important mycotoxin among that class due to high toxicity [41]. Aflatoxin M1 is a principal oxidation product of B1, which is resistant to heat treatment. Aflatoxins are predominantly present in cereals, nuts, and their products [41]. Inferior environmental conditions and development of the country may contribute to increasing the concentration of M1 aflatoxin in milk and dairy products. To analyze this type of mycotoxins in milk and dairy food matrix (goat milk, powder milk, whole, skimmed cow milk, yoghurt), online SPE with HPLC coupled with a fluorescence detector was applied [42]. Commonly, online SPE uses an ultra-HPLC (UHPLC) system with an injection loop and a ten-port switching valve (load or inject set) consisting of a chromatographic column and SPE with a C18 sorbent cartridge. There are many advantages of online SPE compared to traditional (offline) SPE methods, with high throughput being the main benefit [42]. Recently, an increase in the content of mycotoxins in vegetables and fruits was observed, in particular in dried figs, dried vine fruit, dried apricots, plums, and dates.