Once you have identified compounds present in a sample, you need to determine their concentrations based on the data in the spectrum. If you have automatically fit a compound, you may need to refine the suggested concentration.
For more details on techniques for determining optimal profiles for compounds in experimental spectra, see “Tutorial and Sample Files”.
Note that it is not possible to determine (or adjust) the concentrations of compounds that make use of the region-based fit style. For those compounds, you must perform your analysis using compound Areas instead. See “Compound Fit Style” for more details.
To determine the concentration of a compound
-
If the subtraction line (green) is not currently visible, turn it on (see “Legend”).
-
Set a concentration for the compound so that you can see the clusters clearly (see “Concentrations and Compound Fits”).
-
Use the Cluster Navigator to locate a cluster that you can use to approximate the compound concentration (see “Cluster Navigator”).
When choosing a cluster with which to establish a compound's concentration, use a cluster that overlaps other clusters as little as possible.
-
Click and drag the height control for the compound and observe the subtraction line. Adjust the height of the compound until the subtraction line under the cluster approximates a normal spectrum. You may need to move the cluster from side to side somewhat to properly adjust the subtraction line (see “Tutorial and Sample Files”).
-
If any of the clusters for the current compound overlap with compounds that you have already profiled, you may need to readjust those compounds.
-
Compound concentrations are shown in the Compound Table (see “Compound Table”).