I have a synthetic product and want to test its antioxidant activity. This product is dissolved in DMSO, the problem is that the absorbance of this product increases (antioxidant activity decreases) depending on the concentration.
Is there an explanation?
if the absorbance is higher than the one without the extract (control), that means the extract or product has no antioxidant activity. instead of inhibiting the activity, it might induce the oxidation activity. you can try to dilute your sample, may be it can help to reduce the absorbance reading
i think you should try to minimize the amount dissolved from this product in same volume of DMSO
and your work solution for DPPH absorbance must be in range 0.800 at 515nm
few things can be considered. amount of sample should be small. secondly, prepare a blank for each concentration i.e. DMSO + ur extract this might negate the absorbance of molecules, if any, at the same wavelength. hope this works out. luk
Indeed it might be that light interacts with your compound at the wavelength you use for your experiment. And as already was told, preparing blanks that have only dmso and your compound might provide a solution. Best of luck!
it is a result of conversion of DPPH radical to DPPH stable molecule by extraction of H atom from antioxidant, DPPH radical absorb light higher than the stable DPPH, therefor when mixed with antioxidant the absorbency decreased
DPPH can accept an electron or hydrogen radical to become a stable, diamagnetic molecule, it can be oxidized only with difficulty, and then irreversibly. DPPH shows a strong absorption band at 517 nm due to its odd electron and solution appears a deep violet colour, the absorption vanishes as the electron pairs off. The resulting decolorization is stoichiometric with respect to the number of electrons taken up. To avoid negative DPPH prepare a blank for each concentration i.e. DMSO + test extract.
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