Use of a Free Radical Method to Evaluate Antioxidant Activity by W. Brand-Williams, M. E. Cuvelier and C. Berset may be useful for you

IPA is a good solvent for DPPH. You can use it without changing any other parameter.

Kind regards

IPA- isopropyl alcohol... :D

changing from methanol to IPA should not give problems for DPPH itself. However if you are using ascorbic acid as a reference, you might reconsider changing to BHT or trolox as ascorbic acid has a much lower solubility in IPA

DPPH method is particularly useful

for determination of antioxidants that are soluble

in organic solvents, especially alcohols. Information about this method you can find in this publication:  Brand-Williams W, Cuvelier ME, Berset C, Use of a free radical method to evaluate antioxidant activity. LWT-Food Sci Technol 28: 25–30 (1995).

Better use methanol

Well, it is a few options:

1. Dissolve the DPPH in methanol and add the oils diluted in isopropanol.

2. Both, DPPH and oils, dissolved in isopropanol.

3. Both can be also dissolved in the ethyl acetate.

4. However, I would recommend performing more environmentally friendly analysis using ethanol for DPPH dissolving and oil samples diluted in isopropanol.

I believe that those publications can help:

http://www.sciencedirect.com/science/article/pii/S0308814614014186

http://onlinelibrary.wiley.com/doi/10.1002/ejlt.201400566/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false

http://onlinelibrary.wiley.com/doi/10.1002/ejlt.201300425/abstract

Ethanol will work well with the apropiate curve

Methanol is best solvent for DPPH activity , but any way u can use isopropyle alcohol or ethanol.

Ethanol is also proper solvent for this method.

Ethanol is working fine. I have also employed ethyl acetate in order to use the DPPH method for determining antioxidant activity in olive oil, since olive oil does not dissolve in either ethanol or methanol.

In any case, when you change solvent it is advisable to also repeat your calibration curve (for example the Trolox calibration curve).

Methanol is the best solvent for DPPH activity, If it is not available you can use also ethanol or isopropyle alcohol 

Yes of course you can use other suitable solvent like other alcohols or even chloroform or pt. ether benzene  for DPPH Assay.

You may use ethanol instead of methanol

yes. All solvent that solubilize the DPPH

Use methanol. Is the best solvent for this test

Does anyone have issues with dissolving botanical oils in THF?

if the sample you want to test is nonpolar the resoluts in DPPH will be wrong because DPPH ASAY  is for polar molecules 

@ Luis diaz: But majorly DPPH assay has been used for determining the anti oxidant activity of  fatty acids. The literature proves the same. Can you give some reference related to your suggestion.

Thanks for answering.

Hello All..

I wanna ask some question.

I have crude extract that I got from endophytic fungi extracted with ethyl acetate. After done with rotary evaporator, I still maintain the extract in liquid form rather than solid or powder form.

Now, I will do DPPH assay, can I use my extract in ethyl acetate to that assay? I've read that ethyl acetate can be used in DPPH assay, but how with positive control? Can I use ascorbic acid in positive control, or the other?

Or there are other method I can use to do DPPH assay?

Thanks.

Sure, absolute ethanol works better than methanol

Hello,

For using another solvent for the DPPH you can use ethanol. However for oils if you want to measure the antioxidant activity you must make a liquid/liquid extraction for the phenolic compounds using two solvents system 60hexane/40 ethanol:water (the hexane is to dissolve the fatty fraction and ethanol:water for phenolics recovery) after three time extract you recover the extract of the polar solvent by rotavapor system. Once you have the extract you can make a serial dilutions and measure the antioxidant activity by DPPH which was dissolved in ethanol (absorbance at 515 must be between 0.5 to 0.7).

With best of luck.

My greetings.

Hi

Can anybody guide me with DPPH of films of plant extracts. i have made films of plant extract using a polymer. now want to perform DPPH assay. but not sure how to do that. means should i be using solution of extract plus polymer? if yes than how to define the amount to solution to be used?

or i have to use films? but i this case films dont dissolve in ethanol, methanol or water? so what should i do now? can use solvent

yes.

some researches that I have found use ethanol for dpph and dmso for the organic compounds.

Geeta Yadav hi! were you able to successfully conduct dpph assay using other solvent? please share!

Hi, can you please share the reference where they have use ethanol for DPPH assay?

Hi. I made the assay with DPPH in acetone because my extracts were not completely soluble in methanol but were soluble in acetone.