Improving Match probability

This topic describes how to improve Match probability with library compounds.

Restrict m/z Range

Allows to limit the m/z range used in the search. If you know the approximate m/z values of interest, you can exclude the rest and consequently increase the Match probability. If you enter an incorrect range, a dialog will inform you of the valid m/z range for the current chromatogram.

Use Selected m/z

Defines which m/z values should or should not be included in the search.

• Search Only Selected – searches only the defined m/z values. Suitable when you know the typical m/z for the compounds of interest.
• Search All But Selected – excludes the selected m/z values from the search. Useful, for example, when you want to avoid interference from a solvent signal.

Background subtraction

Specifies exact retention time points or intervals to be excluded from the search. These values can be entered manually or selected directly in the graph.

Preview Spectrum in Library

Shows the search results, based on the above-mentioned options, directly in the NIST library. You can check here, whether your setting were right, or even find out the typical m/z for selected compounds.