Hi,
I did the total flavonoid test but the standard solution curve does not seem good enough (R square 77 percent, Can I run just the standard sololution again? Or do I have to do the whole test including samples? Many thanks for your help
You have use Quercetin as the standard. AlCl3 should be prepared in ethanol.
Should get regression R2 above 0.95 usually you can get 0.99 for the HPLC calibration curve.
Hi Pery,
Personally, I would re-prepare the whole lot again, i.e. samples AND standards. In case you have not performed any linearity tests yet, only prepare the standards so you can be sure the procedure is working for the whole range you are investigating (both, the high end and the low end).
If you know the test is linear in the range your samples fall in, I would recommend preparing all samples as at the same time as feasible. Also, instead of only running the calibration curve followed by the samples, I prefer running the calibration curve, followed by my samples with the highest and lowest standard queued every 10 samples or so. This way you can also see if there is any drift during the run.
Good luck!
Pery,
First, make sure that you are not overloading the detector as was done with your Folin-Ciocalteu experiments. And then remember that different flavonoids respond to aluminum chloride differently. To see a good open access paper on this look at http://link.springer.com/article/10.1007/s12161-014-9814-x. Any particular flavonoid will generate a great standard curve. However, the slope of the curves will not be identical. X mM solution of one flavonoid will NOT necessarily generate the same absorbance as X mM of a different flavonoid.
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