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. The thresholds are defined in the project settings and shown as dashed lines in the MS Spectrum window. Lower peaks are considered not detected.
Pre-FLP Response Threshold (%): For pre-peak ions (that is, ions < FLP m/z). Default value is 0.2%.
Post-FLP Response Threshold (%): For post-peak ions (that is, ions > FLP m/z). Default value is 0.3%.
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.
The application evaluates all peaks in the standard condition MS spectrum. The possible classifications are listed in the following table. They are applied from top to bottom, that is, first all Known ions are identified before Unresolved ions are evaluated.
NOTE
m/z values are shown rounded to 1 decimal place. The m/z values at boundaries of m/z intervals may be excluded due to calculations with exact numbers.
# | Proposed classification | Description | Ion name | Theoretical | Measured | m/z used for |
|---|---|---|---|---|---|---|
#1 | Known | Applied if standard conditions peak is above threshold, and is the only or the highest peak within ± 0.5 m/z of theoretical mass. Type Ion in the ion list. | From ion list | From ion list | From standard conditions peak | Theoretical |
#2 | Unresolved (known) | Applied for any standard conditions peaks above threshold within ± 1 m/z of theoretical mass of a Known. | "Unknown " + measured m/z | N/A | m/z from harsh conditions peak, if it is above threshold and within ± 0.5 m/z of the evaluated standard conditions peak. Otherwise, m/z from standard conditions peak. | Measured m/z |
#3 | Adduct (known) | Applied if standard conditions peak is above threshold and within ± 0.5 m/z of theoretical mass. Type Adduct in the ion list. | From ion list | From ion list | m/z from standard conditions peak | Theoretical |
#4 | Adduct (unknown) | Applied if standard conditions peak is above threshold, but harsh conditions signal is below threshold. | "Unknown " + m/z from standard conditions peak | N/A | m/z from standard conditions peak | Measured m/z |
#5a #5b | Unknown (unknown) Unresolved (unknown) | Any other standard conditions peak above threshold. The highest peak is set as Unknown. Peaks within ± 1m/z are Unresolved. | "Unknown " + measured m/z | N/A | m/z from harsh conditions peak, if it is above threshold and within ± 0.5 m/z of the evaluated standard conditions peak. Otherwise, m/z from standard conditions peak. | Measured m/z |
#6 | Not detected | Standard conditions peak of a known ion from the ion list (± 0.5 m/z of theoretical mass) is missing or below the threshold. | From ion list | N/A | N/A | No EIC is performed. If classification is changed, EIC is extracted. |
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 the configured pre-peak and post-peak thresholds.
To change the classification:
Select the relevant ion or ions. Double-click the cell for the user classification, and select the preferred ion class from the drop-down list. Available options depend on the current ion.
To select multiple ions, hold the Ctrl or Shift key while clicking. If you reclassify multiple ions, a new classification is only applied if it is also valid for the respective ion.
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.
To mark ions as degradation products, select the check box in the Degradation product column. These ions will be used to calculate the total degradation product impurities.
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.
base-id: 11123941259
id: 27021608888164235