The DPPH i used was 0.5mM. I dissolved my ascorbic acid in methanol to get 2mg/mL. I'm doing half serial dilutions and i do dilution using methanol. My DPPH i dissolved it in Methanol. I'm in the rights track right? I did this last time, and i can get it. but when i want to do it again, i couldn't get a nice reading. please help.
The most common error in the preparation of calibration solutions is poor mixing. Try to mix the solutions very well at each stage. Perhaps this will be enough.
be careful, ascorbic acid is sensitive and oxidizes quite quickly (few hours). You should only work with freshly prepared solutions.
I did work with freshly prepared solution. Still, it gave me non stable reading. I'm out of idea now.
I agree with Fabrice, ascorbic acid gets oxidized very quickly even in presence of atmospheric oxygen. May be this is one of the factors responsible for not getting consistent results in repeat experiments. No need to get out of idea. Repeat the experiments and then take the mean of the very closely similar results so that you remain with the limits of your desired SD.
As it is said ascorbic acid get quickly oxidized and I hope your successive dilution come from a stock solution freshly prepared. Maybe you can try trolox as positive control. I have used it and it is quite stable.
- Badges
- Science topic
- Similar topics
- Mathematical Sciences
- Statistics
- Statistical Software
- SPSS