I have tested total flavonoids both quantitative and qualitative but the qualitative results show no characteristic change and absence of flavonoids.
At the same time, in quantitative, it shows 0.180, and 0.334 in OD at 510nm.
Qualitative flavonoids:
Procedure.
In a test tube containing 0.5 ml of alcoholic extract 5-10 drops of dilute HCl and a small piece of ZnCl2 or Mg were added and the solution was boiled for few minutes. In the presence of flavonoids reddish pink or dirty brown color was produced.
Result: No characteristic change seen, absence of flavonoids.
Quantitative flavonoids:
procedure:
100mg of the sample was dissolved in 1ml of water. From this 250 µl sample was taken and mixed with 1.5 ml of water followed by 75µl of sodium nitrite Then the mixture was incubated for 6 minutes.150 µl of aluminum chloride was added to the above mixture and incubated for 5 minutes.The solutions were mixed well and absorbance was measured at 510nm.The calibration curve was plotted by preparing the Quercetin solutions at concentrations 100 to 1000mg/Lin DMSO.
Name of sample OD at 510nm Units(μg/ml)
powder A 0.180 500
powder B 0.334 910
If you would like to measure flavonoids with a state of the art method and in vivo, I would recommend reading the literature published by Cerovic Z.G.
A new optical leaf-clip meter for simultaneous non-destructive assessment of leaf chlorophyll and epidermal flavonoids. Cerovic ZG, Masdoumier G, Ghozlen NB, Latouche G. Physiol Plant. 2012 Nov;146(3):251-60. doi: 10.1111/j.1399-3054.2012.01639.x. Epub 2012 Jun 6.
Source: Laboratoire Écologie Systématique et Évolution, Université Paris-Sud, UMR 8079, Bât. 362, Orsay, F-91405, France. [email protected]
Also have a look at his company FORCE-A, which sells the fluorescence based instrument to measure polyphenols, flavonoids and anthocyanin in plants and grapes for example.
There is nothing better than the method he has developed and commercialized for the wine industry in Europe. It will liberate you from the type of question you have asked here in the Q&A. Wet chemistry for flavonid quantification is passé.
Physically based methods (fluorescence) is the state-of-the-art now
Cheers,
Frank
Flavonoids may occur in the plant either in the free sate or as glycoside. In glycoside state it will not respond positively to Schinoda Test (heating the sample with Zn or Mg/HCl) in your case of negative result in qualitative analysis. You may try this test after hydrolyzing the sample, and then it may give positive results, if flavonoids are actually present in your sample. For all analytical issues on flavonoids, you may consult the Book titled “The Flavonoid” by K.R. Markham and T.J. Mabry.
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