Flavonoids HPLC analysis

Ferreres, F., Tomas-Barberan, F. A., Soler, C., Garcia-Viguera, C., Ortiz, A., and Tomas-Lorente, F. (1994f). A simple extractive technique for honey flavonoid HPLC analysis. 

NUUTILA A M, KAMMioviRTA K and OKSMAN-CALDENTEY K-M (2002) Comparison of methods for the hydrolysis of flavonoids and phenolic acids from onion and spinach for HPLC-analysis, Food Chem, 76, 519-25. 

D. Cristea, I. Bareau and G.Vilarem, Identification and quantitative HPLC analysis of the main flavonoids present in weld (Reseda luteola L.), Dyes and Pigments, 57, 267 272 (2003). 

Fig. 2.55. Gradient reversed-phase HPLC analysis of flavonoids in white onions (a) and celery (b). ODS column of 150 X 3.9mm i.d particle size 5pm. Mobile phase 20min gradient of 15-35 per cent acetonitrile in water adjusted to pH 2.5 with TFA. Fowrate lml/min. Upper and lower traces represent samples before and after hydrolysis, respectively. Detection wavelength 365 nm. IS = internal standard Qc = quercetin Ap = apigenin Lt = luteolin. Reprinted with permission from A. Crozier et al. [159],...

Another isocratic elution method was applied for the determination of flavonols in green and black tea leaves and green tea infusions by RP-HPLC. The chemical structures of the flavonols studied are shown in Fig. 2.66. Infusions of teas were prepared by mixing lg of tea leaves with 100 ml of boiling water for 5min, then they have filtered and used for HPLC analysis. The infusion step was repeated three times. Flavonoids were hydrolysed by mixing lg of tea leaves with 40 ml of 60 per cent aqueous ethanol and 5 ml of 6 M HC1. The suspension was heated at 95°C for 2 h, then filtered and the volume was adjusted to 50 ml with 60 per cent aqueous ethanol. Separation was performed in an ODS column (150 X 4.6mm i.d.) operated at 30°C. The isocratic mobile phase consisted of 30 per cent aqueous ACN in 0.025 M KH2P04, and the pH was adjusted to 2.5 with 6 M HC1. The... 

Because of their beneficial biological effects, the fate of flavonoids in human tissues has been extensively investigated [200, 201], Mass spectrometry as a reliable detection technique has been frequently used in the HPLC analysis of flavonoids [202, 203],... 

Among the numerous applications of SPE are separations of phenolic acids and flavonoids from wines and fruit juices. Sep-Pak Cig cartridges have been used for the fractionation of flavonol glycosides and phenolic compounds from cranberry juice into neutral and acidic parts before HPLC analysis. Antimutagenic flavonoids were identified in aqueous extracts of dry spinach after removal of lipophilic compounds by SPE. ... 

Spices (rosemary, sage, thyme) contain considerable amounts of flavonols and flavones, mainly in the glycoside form (154). Thus, phenolic analyses in spices were often considered in order to determine the optimum time for plant collection to give maximum flavonoid contents and for health benefits (154,155). Flavonoids (naringin, luteolin, apigenin, and chrysoeriol) were extracted from spices using a percolation process at room temperature with solvents (MeOH and EtOAc), and HPLC analysis was carried out (155). 

This is achieved by adding 0.5 mg of flavonoid to 3 mg of 3-D-glucosidase in 0.5 mL of 0.1 M citrate-phosphate buffer, pH 5 (37 °C, 24 h). The hydrolysis products are then extracted with ethyl acetate, taken to dryness under reduced pressure (40 °C), and redissolved in methanol for HPLC analysis (Gil et ah, 1998). 

HPLC analysis of flavonoids and phenolic compounds and acids... 

As regards the sensitivity of the MS detection in HPLC analysis of flavonoids, this technique has proved to be the most sensitive as compared to UV and fluorescence detection. A very comprehensive comparison of the four detection systems—UV, fluorescence, and two MS systems [atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI)]—for the determination of the previously identified 3, 4, 5 -trimethoxyflavone is presented in Table 1. Fluorescence detection is 10 times more sensitive than UV detection, whereas MS detection is 50 times more sensitive than UV detection and 5 times more sensitive than fluorescence detection. 

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