# Application of Sorbent-Based Extraction Techniques in Food Analysis
## 3 SPE in Food Analysis--Main Fields of Applications
### Environmental Contaminants in Food
Flame retardants are a class of compounds containing emerging halogenated flame retardants, organophosphate flame retardants, and polybrominated diphenyl ethers. These compounds were added to many industrial products (building materials, electronics, foams, furniture, textiles) to prevent the fire from spreading. In the last decade, it has been discovered that despite their good operation during a fire, they are also extremely toxic and persistent in an environment where they accumulate and, therefore, their use has been banned. Flame retardants have been detected in air, soil, water and living organisms, and consequently also in food [64]. In the determination of these compounds, pigments, and lipids most often interfere, which can be eliminated during the sample cleaning step. The most commonly used technique for this purpose is the d-SPE with C18, Z-SEP or PSA sorbent. This technique has been successfully applied to beacon, chicken eggs, chicken thigh, lean beef, lean pork, mussels, prawn, salmon, smoked salmon, and tuna [64]. Vegetables are highly vulnerable to the absorption of organic impurities that can accumulate via the root system, especially when they are irrigated with recovered wastewater or sewage sludge from wastewater. Bioaccumulation depends on the nature of the contamination and the part of the plant, e.g., in the root (carrot, potatoes, turnip), the compounds with the anionic, neutral and cationic structures are most often accumulated while in the leaves (chard, lettuce, spinach) this order is reversed. Environmental contaminant accumulation influences crops and has potential adverse health effects (cancer and metabolic disorders, reproductive damage). Plant absorption is evaluated with particular emphasis on the analysis of antioxidants, disinfection by-products, flame retardant compounds, perfluoralkyl compounds, personal care products, pharmaceuticals, and plasticizers [65]. As a result of these compounds that are present in trace amounts, an appropriate extraction method is required (focused ultrasound solid-liquid extraction, matrix solid-phase dispersion, pressurized solvent extraction ultrasound-assisted extraction), after which the concentration of the target analyte is necessary. The most commonly used technique for clean-up and enrichment samples is SPE or d-SPE with a polymeric sorbent applying an ion-pair reactant [65]. Chloramphenicol is a popular antibiotic, which was isolated in 1947 from _Streptomyces venezuelae_. A wide spectrum of activity against pathogens (Gram-positive bacteria, Gram-negative bacteria, and some of _Chlamydia_ and _Rickettsia_ species) and high efficiency lead to use against bacterial diseases in both animals and humans [66]. Unfortunately, chloramphenicol residue in edible animals enters the food chain. Routine determination of this compound is carried out by ELISA and chromatographic methods. Before determination by utilizing chromatography techniques, it is necessary to pre-clean the sample with SPE with magnetic molecularly imprinted polymers as a sorbent [66].