Vibrational Spectroscopy for Detection of Chemical Contaminants
The capability of vibrational spectroscopy to detect all the biochemical compounds of a cell has led to the emergence of FT-IR and SERS as competent tools for the analysis of trace amounts of chemical hazards in various food products. The applications of vibrational spectroscopy fingerprinting to detect chemical contaminants in various food stuffs, such as dairy products, fish, fruits, vegetables, and condiments, have been reviewed in detail (Fan et al., 2014; Zheng and He, 2014).
Most studies reported are targeted on detecting melamine in milk, milk powder, infant formula, and egg white (Betz et al., 2012; Hu et al., 2015; Wang et al., 2015). Besides detection of melamine at very low concentrations (63 ppb to 2 ppm), quantification was also possible.
The characteristic of vibrational spectroscopy to be applicable directly on food surfaces without destroying the food gives it an enormous potential to detect pesticides on fruit and vegetable surfaces. In this sense, pesticide residues could be detected on apple surfaces and in apple juice samples at concentrations of 0.125 pg/cm2 and 3 pg/mL (3 ppm), respectively (Wijaya et al., 2014). Pesticides could also be detected in mixtures (Zhai et al., 2015) and on the surfaces of further fruits, such as bananas and citrus fruits (Muller et al., 2014).
Further chemical contaminants that have been investigated by FT-IR and Raman spectroscopy are banned food additives, such as sudan I, rhodamine B, and malachite green (He et al., 2015). Likewise, the contamination of fish with heavy metals could be detected by vibrational spectroscopy (Chen et al., 2013).
