Citrus chromatographic methods

F. I. Kanaze, C. Gabrieli, E. Kokkalou, M. Georgarakis and I. Niopas, Simultaneous reversed-phase high-performance liquid chromatographic method for the determination of diosmin, herperidin, and naringin in different citrus fruit juices and pharmaceutical formulations. J. Pharm. Biomed. Anal. 33 (2003) 243-249. 

Determination of Limonin Content. A summary of the methods reported through 1976 for the quantitative determination of limonin in citrus juices was published previously (3 ) Since then improvements have been made in the high-pressure liquid chromatographic method (44, 45) and advances have been made in the development of enzymatic (46) and immunoassay (47, 48) (see Chapter 15) methods. The latter methods hold great promise for the future. However, in each case the required enzyme or antibody is not yet commercially available. Thus, while substantial progress is being made the need still exists for a simple, sensitive, and rapid commercially available method for routine industrial quality control purposes. 

Chromatographic methods were developed to separate a few of the citrus flavonoids from the complex mixture of citrus flavonoids. The early paper chromatographic methods for flavanones (22, 23) were difficult to quantitate because of band broadening and uneven solvent development. Several thin layer chromatographic (TLC) methods were developed to separate the bitter from the nonbitter flavanone glycosides (24, 25, 26, 27). 

Basically, different techniques can be employed to optimally concentrate citrus oils distillative, extractive and chromatographic methods are available frequently combined multi-step technologies are used. However, cold procedures are apparently the first choice in citms oil processing (see chapter 2), if the following aspects are considered ... 

The analysis of essential oils by means of GG began in the 1950s, when Professor Liberti [31] started analyzing citrus essential oils only a few years after James and Martin rst described gas-liquid chromatography, commonly referred to as GG [32], a milestone in the evolution of instrumental chromatographic methods. 

This method is only partly applicable to the analysis of citrus juices, since the citric acid contained at high concentrations in these products is strongly retained under the given chromatographic conditions. After repeated injection, this results in a marked reduction of the exchange capacity. Therefore, a gradient technique with sodium hydroxide as the eluent must be used for analyzing such samples (s. Fig. 3-124 in Section 3.3.6). 

Method C The peel obtained from each citrus was chopped and extracted with cold MeOH in darkness for three days. The MeOH extract was successively treated with n-hexane, EtOAc and n-BuOH. The n-BuOH extract was chromatographed over a Diaion HP 20 column. The column was washed with H2O, and successively eluted with 20% MeOH-H20, 60% MeOH-H20 and MeOH. The 20% MeOH-H20 eluate was concentrated in vacuo, giving a mixture of crude phenylpropanoid glycosides. Phenylpropanoid glycosides (52, 53, 54, 56, 57, Fig. 2 and Table 2)[25] were purified by column chromatography on silica gel and by gel filtration on HW-40F TSK gel. 

Another, more complex, method for the concentration of citrus oils is a chromatographic separation using packed columns. This method allows a complete elimination of the unwanted hydrocar bons. This method, invented by Erich Ziegler, uses columns packed with either silica or aluminum oxide. The oil is introduced onto the column and the hydrocarbons eluted by means of a suitable nonpolar solvent of very low boiling point. The desirable polar citrus oil components are then washed out using a polar solvent (Ziegler, 1982). 

Pellati F, Benvenuti S (2007) Chromatographic and electrophoretic methods for the analysis of phenetylamine alkaloids in Citrus aurantium. J Chromatogr A 1161 71-88... 

Friar, P. M. K. and Reynolds, S. L., 1994. The effect of home processing on postharvest fungicide residues in citrus fruit residues of imazalil, 2-phenylphenol and thiabendazole in home-made marmalade, prepared from Late Valencia oranges. Food Add Cont 11, 57-70. Gonzalez, M., Gallego, M. and Valcarcel, M., 1999. Gas chromatographic flow method for the preconcentration and simultaneous determination of antioxidant and preservative additives in fatty foods. J Chrom A 848, 529-536. 

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