Ion Classification confirms impurities that coelute with the FLP. The corresponding ions (that is, m/z values) are then used to determine the extracted ion chromatograms that are used to calculate the MS purity of your sample.
The classification of ions is based on relative spectral values that exceed specific thresholds and meet the following criteria:
For pre-peak ions (that is, ions < FLP m/z), the threshold is 0.2% of FLP peak height.
For post-peak ions (that is, ions > FLP m/z), the threshold is 0.3% of FLP peak height.
For details on how the application assigns the classifications, see the following table.
Any ions above the threshold must be reported, but not all will require EICs. For example, any ions within ± 1.0 of a given identified known or unknown impurity that exceed the threshold are classified as insufficiently resolved. These ions will not require EICs for integration.
|
Ion |
Description |
Result |
|---|---|---|
Known | A peak higher than the threshold and within ± 0.5 m/z of known ion (type: Ion) from the ion list. If there are several peaks satisfying this condition, then the highest one is labeled as Known and the others are labeled as Unresolved. | Perform an EIC using m/z value from ion list |
| Unknown | Ion that exceeds the threshold but is not within ± 0.5 m/z of any of the components in the ion list, and harsh condition spectrum for the same m/z as the standard peak is higher than the threshold. If there are several peaks satisfying these conditions, then the highest one is labeled as Unknown and the others are labeled as Unresolved. | EIC is performed from the standard condition spectrum, using the m/z value of the highest peak from the harsh spectrum within ± 0.5 m/z of the standard spectrum peak. If there is no harsh peak withing ± 0.5 m/z of the standard spectrum peak, or the harsh peak is below the threshold, then the standard peak m/z is used. |
| Unresolved |
MS spectra peaks above threshold and within ± 1.0 m/z of an already labeled known or unknown impurity. | No EIC is performed |
|
Adduct | Known adduct, if a peak is higher than the threshold and within ± 0.5 m/z of known adduct (type: Adduct) from the ion list. Unknown adduct, if a peak is higher than the threshold and > 0.5 m/z of known adduct (type: Adduct) from the ion list, harsh condition spectrum for the same m/z as the standard peak is smaller than the threshold | No EIC is performed |
| Not detected |
Known ion from the ion list with the corresponding MS peak below the threshold | No EIC is performed |
Ion Classification is separated into three steps:
The first step confirms each integration and extraction of TIC and spectrum, respectively. The begin and end time of this TIC is displayed in the table and shown in the graph. Each corresponding MS spectrum is displayed as well over the time window given in the table.
To perform an overlay of both TIC and spectra, hold the [Shift] key and select the row for each sample prep (standard and harsh). This may be useful for confirmation that the sample type for standard and harsh conditions were selected correctly in Data Analysis.
The next step shows the classification of each ion, based on the algorithm and criteria in the preceding table. Ions are listed in the Classification table, and are sorted based on user classification.
To sort the table, click the header of the relevant column.
Zoom in to investigate the spectra, and confirm that each ion was classified correctly. The spectrum window has dotted lines representing 0.2% and 0.3% for pre-peak and post-peak thresholds, respectively.
To change the classification for an ion, double-click the cell for the user classification, and select the preferred ion class from the drop-down list.
The final step is a summary of the ion classification. The table shows only the known and unknown ions based on user classification. These are the only m/z values that will be used to perform the EICs used in the Integration section.
If everything is correct, click Next to proceed. Confirm that you finished the classification settings. You will not be able to return to this step. Your changes are then saved as a new version of the result set.