High-performance liquid chromatography-diode array detector (HPLC-DAD) coupled with electronspray mass spectrometry (ESI-MS) was used to detect the flavonoid profile in lemon juices obtained from the main Sicilian cultivars (Femminello comune, Monachello, and Interdonato). Significant amounts of an unusual constituent were found in the lemon juice of the above-mentioned cultivars together with eriocitrin, hesperidin, and diosmin. Following purification by preparative HPLC, the structure was assigned as 6,8-di-C-glucopyranosyldiosmetin by means of DAD-UV, ESI-MS-MS, and (1)H NMR analysis. Three other minor components were also detected. One of these presented a flavone nature, and spectral data and literature references both suggested a 6,8-di-C-glucopyranosylapigenin structure. The different contents of eriocitrin, hesperidin, diosmin, and above minor components in the cultivars allow juices to be readily differentiated.

Flavanone glycosides (FGs) and polymethoxylated flavones (PMFs) have been studied in pigmented orange (Citrus sinensis) juices and second-pressure extracts (SPEs) by high-performance liquid chromatography and diode array detector. Detection was performed simultaneously at two different wavelengths: 278 nm (for determination of FGs) and 325 nm (for determination of PMFs). Qualitative distribution patterns of FGs and PMFs in juices and SPEs were similar, although the quantitative results are quite different. An increased narirutin/hesperidin ratio after centrifugation and the presence of high amounts of PMFs in SPEs, which remain unchanged after centrifugation, were observed. Therefore, a simple and affordable procedure to distinguish an orange juice from SPEs was proposed.