Frequently Asked Questions

LC Simulator

Q: How do I add a second solvent to the mobile phase in LC Simulator and edit the gradient program.

A: To add a second solvent to the mobile phase:

  1. Open a file in SpecManager and click the Edit/Show Chromatogram Parameters button (beside the LC Simulator button near the top right).
  2. Click the Mobile Phases button
  3. Right-click in the header for Phase A and click Add.
  4. A new tab for Phase B appears that can be edited with a second solvent. Also, there is an additional section on the right where you can enter a gradient program.

Q: When the column length is decreased in the Data Input dialog box, the retention time will increase. If the column length is increased, the retention time will decrease. However, any changes to the column length under Tools/Column Optimization cause the retention time to change correctly.

A: This is not a bug. The Data Import dialog box is for use when the data is first imported into LC Simulator. When the data is first imported, it automatically fills in the column length information in the Column Optimization window (from the Tools menu, choose Column Optimization). The column length first imported is now known as the Experimental column length. The link between these two windows is lost once the import of data is accepted. Changes to the column length in the Data Import dialog box change the experimental column length, while the chromatogram is predicted using the old column length that is in the Column Optimization dialog box.

If the previous column length in the Column Optimization dialog box is now more than the new column length in the Data Import dialog box, the predicted retention time (tR) will be increased. For example, if a file is initially opened with a column length of 10 cm, and then this value is changed in the Data Import dialog box to 5 cm, the program assumes that the chromatogram being imported currently has a column length of 5 cm, and that the prediction is for a 10 cm column. The software changes the chromatogram to show retention times that are double that of the previous times.

The Data Import dialog box is only to be used when initially putting the HPLC parameters into the software. To perform optimization of the data for the column length, from the Tools menu, choose Column Optimization.

Q: Is it possible to change the prediction model?

A: For Prediction, you cannot change the model, it will always use the linear equation. The prediction works accurately only for similar structures. Especially when you have a linear model, it is better to operate with similar physicochemical values and get better correlation.

Q: In SpecManager we can set a number of decimals to be viewed for tR. When it comes to LC Simulator, the values are truncated to 2 decimals. Why?

A: Currently LC Simulator has a limitation to accept only values with 2 decimals.