# Application of Sorbent-Based Extraction Techniques in Food Analysis
## 4 SPME in Food Analysis--Main Fields of Applications
### Processing Contaminants  
Safety is generally one of the main goals of food analysis. Many efforts have been made to ensure the highest quality of reconstituted products. Food processing, like cooking, fermentation, packing, transport or storage, is a significant source of contamination. Thus, it is important to monitor food at each step of the production process. The amounts of hazardous substances are regulated by appropriate institutions, which describe the minimum level recognized as safe for humans. Cooking is a well-known process that causes substantial changes in food stuff, and some common contaminants such as heterocyclic amines, acrylamide or PAHs can be formed at a higher temperature. All the mentioned compounds were determined in food products by the SPME technique. [PERSON] and co-workers [125] used SPME coupled with HPLC with a DAD for the analysis of heterocyclic aromatic amines. The authors compared four different fibers for the extraction efficiency of heterocyclic aromatic amines from beef extracts. CW-TPR fiber was recommended as the most suitable, enabling the determination of heterocyclic amines at low ng/mL levels. The only difference between SPME-GC and SPME-HPLC is the desorption step. An HPLC-specific interface with an appropriate fiber-desorption chamber is required. Through the interface, the mobile phase contacts the SPME fiber, and the absorbed compounds are removed and flow with the mobile phase to the column [126]. Acrylamide is a very common processing contaminant, occurring in starch products under the influence of high temperatures (above 120 \({}^{\circ}\)C). In 2015, the EFSA published a full risk assessment of this substance present in food. Experts concluded that it potentially increases the risk of cancer development. SPME coupled with GC-MS/MS was used for the direct determination of this toxic compound in aqueous matrices [127]. The obtained LOD was 0.1 ug/L. The proposed method was successfully applied for the quantification of acrylamide in products like French fries or potato chips. Another example of the application of SPME was the determination of furan in baby food samples. This compound is regarded as a possible carcinogen (group IIB) by the International Agency for Research on Cancer. The high volatility of furan causes its determination to be challenging. SPME followed by GC-MS was developed and gave satisfactory results in different matrices. The amount of furan analyzed in baby-food samples varied between 4.7 and 90.3 ug/kg. It was proved that the technique was appropriate for reliable determination of furan. Obtained LOD and LOQ parameters were, respectively, 1.9 ug/kg and 4.0 ug/kg [128]. 3-monochloropropane-1,2-diol (3-MCPD) is considered a possible human carcinogen and the European Commission Scientific Committee on food determined 2 g/kg body weight as a safe daily intake. Determination of extremely low quantities of 3-MCPD in the food matrix poses a challenge for analytical chemists despite impediments such as a high boiling point or low molecular weight negatively affecting separation by GC-MS. This technique became commonly applied in analytical laboratories; however, the substance requires derivatization before analysis to overcome the problem of low volatility and high polarity. Derivatization also solves the problem of low molecular weight, which makes it difficult to distinguish the 3-MCPD from background noise. The trend of looking for new techniques is focused on the elimination of liquid extraction and labor-intensive steps in sample preparation, ideally following green chemistry principles. Meeting these requirements, SPME-GC-MS was developed for 3-MCPD determination in liquid hydrolyzed vegetable protein and soy sauce. The LOD was 3.78 ng/g [129]. Later, [PERSON] and colleagues [130] used the technique to determine 1,3-dichloro-2-propanol and 3-MCPD in soy sauce samples and obtained an LOD for 3-MCPD 4.62 ng/mL.