## 4 Applications in Food Analysis
### Volatile Toxic Compounds  
Various sources of microbiological and chemical hazardous compounds may occur in foods. The latter may include natural toxicants, such as mycotoxins [305, 306, 307], marine toxins [308], and environmental contaminants, such as mercury and lead [309, 310, 311, 312, 313, 314].  
Among these substances for example volatile toxic aldehydes like formaldehyde has recently received increased attention. Formaldehyde is formed post-mortem by the enzymatic reduction of trimethylamine-N-oxide to formaldehyde and dimethylamine [315, 316]. Due to its high volatility, formaldehyde is captured well by SPME for subsequent measurement. Firstly, in 2005 [PERSON] _et al_. [317] developed a SPME method with _in situ_ derivatisation with pentafluorobenzyl-hydroxylamine hydrochloride (PFBHA). In 2007, [PERSON] _et al_. [81] used a SPME-GC-MS method based on the same derivatization to evaluate the formaldehyde content of various fish products.  
Additional non-flavor contaminants are polycyclic aromatic hydrocarbons (PAHs), identified as pollutants in the environment and food items [1, 2, 3]. [PERSON] _et al_. [276] developed a SPME method with a coating based on the use of diethoxydiphenylsilane produced by sol-gel technology for determination of PAHs at trace levels in milk. For vegetables, a simple, sensitive and affordable method has been developed for the quantitation of eight PAHs by [PERSON] _et al_. [289]. The method was based on HS-SPME connected with GC-FID. The sol-gel designed benzoxy-C[6]/OH-TSO proved to have a good capability to capture aromatic compounds such as phthalate acid esters. Compared to the tested PDMS fiber and C[4]/OH-TSO fiber, the benzoxy-C[6]/OH-TSO showed to have the highest affinity to PAHs [289].  
The VOCs 2-nitropenol and 3-fluoroaniline were extracted, separated and detected by headspace-solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS). It was stated to be a potential rapid method for future development [275].  
Microorganisms can also be responsible for food contamination and spoilage. The metabolic activity of microorganisms through breakdown of compounds in food leads to the release of volatile organic compounds [41]. Extensive research was carried out in order to identify microbial activities in foods using SPME [275, 288, 297, 318]. [PERSON] and [PERSON] [288] investigated the occurrence of _Salmonella typhimurium_ present in packaged alfalfa sprouts. For that purpose CAR/PDMS fibers were compared to PDMS/DVB fibers which extracted lesser sulfur volatiles. Sulfur-containing compounds seem to be a major marker compound for spoiled food stuffs, off-flavor in milk, and the presence of pathogens [288]. Other volatile organic compounds such as 2-nitropenol and 3-fluoroaniline may be associated with the presence of _Listeria monocytogenes_ contamination in food [318].  
Pesticides are not only contaminants, but are also non-flavor compounds occurring in food items. The simultaneous determination of fourteen multiclass pesticide residues in fruit and vegetable samples by means of HS-SPME coupled to GC-MS were reported by [PERSON] and [PERSON] [287]. The method development was based on multivariate experimental designs (Plancket-Burman and central composite design) conducted in two stages. Internal standard calibration was applied for quantitation (detectionlimits between 0.35 and 8.33 \(\upmu\)g/kg). Compared to liquid-liquid extraction techniques and SPE, which are commonly used in pesticide analysis, SPME takes less time, is less labor-intensive, does not require any solvents and simplifies sample preparation to one single step and one device [41].