HPLC/MS interpreation of peak area

2 posts / 0 new
Last post
lakeduck
lakeduck's picture
HPLC/MS interpreation of peak area

 Hello,

I have HPLC/MS chromatograms from my standard and my substance. I am trying to get a little close to the concentration of my substance by comparing the peaks areas, but i don´t know the units of the peaks. I know this is not the best method for quantifying, but it is what i have for the moment. 

I also want to know what "intensity" of the MS spectrum refers to.  

Can you help me with this two questions, please?? 

Than you very much. 

LakeDuck

Dr. Analytical
Dr. Analytical's picture
I am sorry that no one else

I am sorry that no one else responded, as I just noticed this post.  If you still need some answers:

Every data system works differently, but the area under the peak is often in units of response X time.  The area is an approximation of the total area under the peak, and is often calculated by summing up all the individual responses across the peak.  Most systems do not even report units, because they are not important (see below).

Intensity is the response from the detector in the MS.  A larger number means a larger response, meaning more ionic fragments reached the detector at that m/z value.  A mass spectrum is just a histogram summary of the responses at the detector for each mass.

To calculate concentration, you need to calibrate your instrument for your analyte.  There are many ways to do this, so find a good book on analytical chemistry and/or chromatography that explains the options. 

The simplest approach is the response factor method:

Response Factor (RF) = Peak Area / Amount Injected.

This ratio is constant (usually) for both standard and sample, so once you have the RF and the sample's peak area, you can calculate the concentration.