Flavanone glycosides (FG) found in citrus juices have been separated and quantitatively determined by reversed-phase liquid chromatography (LC) using a Cle packed column and water-acetonitriletetrahydrofuran-glacial acetic acid eluent system. The influence of juice pH on hesperidin and narirutin determinations, from commercial orange juices, has been studied at different pH values (from 2.0 to 6.2). The response factors, averages, relative standard deviations, and recoveries of six FG were determined using LC with an UV detector at 280 nm. The six FG and three unknown compounds found in citrus juices were determined in 124 samples of lemons, limes, grapefruits, and sweet oranges. The major FG in each citrus group were as follows: in lemon and lime, eriocitrin (47-94 mg L-I) and hesperidin (84-196 mg L-l); in sweet orange, narirutin (30-84 mg L-l) and hesperidin (235-407 mg L-1); in grapefruit, narirutin (33-161 mg L-l) and naringin (113-481 mg L-l). Factorial discriminant analysis of the data obtained effectively differentiated lemon and lime and varieties of grapefruits (white, pink, red, and green) and sweet oranges (Valencia, navel, blood, Thomson, and Malta)

Abstract.A rapid method of extraction and quantitation of polymethoxylated flavones (PMF) using isocratic liquid chromatography is described. With this method the content of six PMF: sinensetin, hexamethoxyflavone, nobiletin, heptamethoxyflavone, tetra-O-methyl scutellarein and tangeretin from 60 commercial orange juices have been determined. The PMF extraction method is mainly established on sample preparations using C 18 cartridge extractions with water/acetonitrile (60/40, v/v) as mobile phase. PMF compositions of orange commercial juices show a quantitative difference on population samples which are linked to the PMF contents and varieties. By these rapid quantitative method, the PMF values observed were in accordance with literature. This technique present correct characteristics of repeatability and reproducibility (4.5% and 6.6% respectively).