Hello, this is my first time determining total flavonoid content (TFC) by colorimetry on plant extract. I have questions to ask regarding this because i'm not sure with the results i got.
I did an extraction on St. Crispus (UAE-ATPE, ethanol and ammonium sulfate), and did a TFC determination by adding 0.5 ml of the diluted extract, 1.5 ml of ethanol, 0.1 ml of 10% Al2Cl3, 0.1 ml of 10% CH3COOK, and 2.8 ml of water. I let the mixture sit for half an hour and found that it seems cloudy so i did centrifugation for 10 min at 5000 rpm.
Though i took only the clear solution for spectrophotometry, the light absorbption measurement of the TFC sample keeps increasing. There was no problem with the spectrophotometer, it only happened to those particular TFC samples.
What might be the fine solids that was formed in the process? Is there anything i could do to fix this?
Thank you in advance. I highly appreciate every response to my question.
Dear Najah,
try to analyze your samples right after adding last ingredient. I'm working with plant extracts in deep eutectic solvents and in TFC method I also notice precipitation after some time, so it is better to analyze it immediately. If precipitate occurs right away, try different method with Al2Cl3. My method: 250 ul of diluted extract, 1250 ul water, 75 ul of NaNO2 (5%), 150 ul Al2Cl3 (10%) and 500 ul NaOH (1M). I hope that You will solve the problem,
Good luck, Agata
I had the same observation when determining TFC in plant extract. The turbidity is caused by the interaction between CH3COOK, AlCl3 and lipid content extracted by the absolute solvent. My supervisor suggested we use of 70% alcohol in distilled water. The cloudiness reduced.
I also recommend the answer given by Ochai Odeh. It will give totally clear solution or leads to minimum cloudiness replacing ethanol by methanol.
Agata Wawoczny Hi! Can you provide me with the material you are referencing?
Hi, here is one of the articles: Article Total Phenolic and Flavonoid Contents of Aqueous Extract of ...
I changed the method slightly. Best regards.
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