Phenolic compounds, analysis

Tomas-Lorente, F. et al.. Phenolic compounds analysis in the determination of fruit jam genuineness, J. Agric. Food Chem., 40, 1800, 1992. 

Phenolic Compounds, Analysis by HPLC P. B. Andrade R. M. Seabra... 

Since phenolic metabolites may be responsible for the antioxidant properties of fruit and vegetables it is essential to know, both qualitative and quantitatively, their phenolic constituents. Although the data is incomplete, and the quantitative data is not reliable due to the very different extraction and analytical techniques used for phenolic compound analysis, the available information is summarised in this paper. As regards fruit phenolics, a comprehensive book has been published, in which qualitative and some quantitative data are provided [16]. The anthocyanins present in fruit, vegetables and grains have also been reviewed [17],... 

Atmospheric pressure ionization (API) has been mainly used for the ionization of phenolic compounds, applying either electrospray (ESI) or atmospheric pressure chemical ionization (APCI), as it can be observed in Table 16.7. However, ESI is more often used to ionize the different families of phenolic compounds. Moreover, APCI and ESI can be operated under both negative and positive ion modes. Although positive ionization mode [47,93,102,103] was used for detection of various phenolic compounds, it was found that negative ionization mode [94,95,101,104,107] was excellent for phenolic compounds analysis. In this sense, the combination of both polarities in the same method provided good results [75,92,99,100] for the simultaneous determination of several families of compounds. Phenolic acids [75,94,95,101,103,107], flavonols [75,94,95,99,101,103,107], flavonones [99,103] flavanols [92,101,103,104], and flavones [75,103] were often detected in negative ion mode, although some of these families were also detected in positive mode [75,99,100,102]. Anthocyanidins [47,100], coumarins [102], and isoflavones [75,93,102] were detected in positive mode. 

According to Joslyn and Goldstein (1964), the Folin-Denis method, published in 1912, was first intended for the measurement of tannins in wine and whiskey, and then used for the assay of tannins in fruits (Swain and Hillis 1959 Craft 1961). Various methods for phenolic compound analysis have been reported (Joslyn and Goldstein 1964 Hartley 1987 Karchesy 1989 Hagerman 1989), but the Folin-Denis method is still very useful for the measurement of phenolic compounds in fruits. 

In phenolic compound analysis FIA is the preferred method rather than conventional chromatographic and spectrometric methods because it offers lower detection limit values, greater sensitivity, short time requirement, lower sample requirement, an easy technique, user-friendliness, and high linearity, recovery, and precision. This system represents a new contribution in the field of automation of analytical methods. 

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