Beginner to get a table of integrated peaks for a specific mass at a specific RT.

<p>I am trying to attempt flux balance analysis on a set of cell samples which were fed 13C labelled carbon sources.</p><p>Let's say I am trying to detect labelled lactic acid. I know the mass of the standard is 89.023 and it comes off the column with a retention time of 7.6min in the negative mode.</p><p>I want to detect the integrated area of the compound with the correct mass, then the one with one 13C label (+1.0034 mass units), two 13C labels, etc.</p><p>The masses of these are:</p><table border="0" cellpadding="0" cellspacing="0" width="256"><tbody><tr><td align="right" height="20" width="64">89.0233</td><td align="right" width="64">90.0267</td><td align="right" width="64">91.0301</td><td align="right" width="64">92.0335</td></tr></tbody></table><p>Which software package do I use to get integrated intensities for each of those masses at a retention time near the one I stated above? </p><p>I can do it manually by going to each sample, and searching for that mass and integrating in the chromatogram viewer, but I am searching for >100 metabolites with multiple possible labelling on two dozen samples.</p><p>Can someone just point me in the right direction.</p><p>I should say that I cannot get MarkerLynx to identify all of the masses as Markersat a specific retention time.</p><p>Thanks </p>