How to integrate vitamin C DAD signal

[vahur]

Hi

I have not worked alot with DAD and therefore don´t know where to look. The problem is following:
My standard peaks looks like this:(probably the calibration peaks also since they were made the same way)

The problem is that analytes peak is surrounded with other peaks and therefore the baseline is higher. Should I integrate the peaks like 1

2

or 3

The concentrations are from different integrations:
1 - 15,0
2 - 15,5
3 - 16,1

[prepcolumn]

At first glance 1st integration seems more reasonable.

To give the more accurate decision you have to compare your analyte chromatogram with your matrix that does not contain ascorbic acid (placebo, blank, etc.). Moreover, if i were you, i would seriously suspect from peak purity because there are many secondary peaks around ascorbic acid.

[vahur]

Moreover, if i were you, i would seriously suspect from peak purity because there are many secondary peaks around ascorbic acid.

I don´t understand what you mean. Could you explain again.

[prepcolumn]

Moreover, if i were you, i would seriously suspect from peak purity because there are many secondary peaks around ascorbic acid.

I don´t understand what you mean. Could you explain again.

Vahur

What i mean is; there are many peaks around your main peak (which may arise from your excipients or impurity peaks of ascorbic acid). This creates (or increases) the possibility that there may also be secondary peaks under the main peak..this situation may also influence your results and the reliability of your method..

Hope it is clear enough

[vahur]

OK, I get it now. Thanks for explaining. I also thought that first on was the most reasonable.