Chromatography Forum

Dear members of this forum,

I do not understand an analysis which I have done for a long time, it is alprazolam in two different tablets products with two kind of hplc columns. These are C8 and cyano. The area of this analite with cyano column and 225 nm is bigger than the same concentration in C8 column. As much as know the detector response is proportional to the concentration of the elution and it is the same and I do not know the response and I appelate to your help.
Thanks in advance for your help,

Diego Delmonte

Peak area is proportional to analyte concentration so long as all injections are made under identical conditions (in other words, same column, same flow, same . . . ). The area is actually proportional to the absorbance of your analyte and to the residence time in the flow cell, so something as simple as a change in flow rate or column diameter will change the response.

In short, you have nothing to worry about; there is no reason to expect exactly the same response for separations done under two different sets of conditions.