In this section of the tutorial, you will investigate a contaminating mass in an unlabeled sample:

Prerequisites

  1. You are viewing the Stable Isotope Labeling
  2. The Compounds table is sorted by Area (Max.) in descending order.

Procedure

  1. In the Compounds table, select the pin icon to left of row #84 to pin the compound (with a Calc. MW of 248.17486 and RT of 11.048 min) to the top of the table.
  2. The row for the compound is pinned to the top of the table, allowing you to scroll down while keeping the row visible.
  3. In the Labeling Status column, select the expand icon for the column.
  4. Compound with Calc. MW of 248.17486 (row #84) in the Compounds table (with the Name and Labeling Status columns frozen at the left).
    Figure Compound with Calc. MW of 248.17486 (row #84) in the Compounds table (with the Name and Labeling Status columns frozen at the left).
  5. The row headers appear. Because you grouped the samples by sample type, the samples are also grouped by sample type in the Labeling Status column.
  6. The unlabeled samples (F2, F3, and F4) are denoted with a red box, indicating the presence of a contaminating mass in these samples.
  7. Select row #84 (if necessary) and then below the Compounds table, select Show Related Tables.
  8. The first-level related tables appear: Structure Proposals, Compounds per File, Predicted Compositions, Features, Labeled Compounds per File, Formulas, Metabolika Results, mzCloud Results, ChemSpider Results, and Metabolika Pathways.
  9. With the Stable Isotope Labeling layout applied, the Labeled Compounds per File table is selected by default.
  10. In the Labeled Compounds per File table, do the following:
  11. Right-click the table and select Enable Column Fixing. Then, select the pin icon for the Exchange Rate [%] column.
  12. Select the expand icon for the Exchange Rate [%] column.
  13. The row headers appear.
  14. The Exchange Rate [%] column shows that the contaminating mass is possibly a compound with a mass of M+9.
  15. Labeled Compounds per File table for the compound with Calc. MW of 248.17486
    Figure Labeled Compounds per File table for the compound with Calc. MW of 248.17486
  16. Refer to View a trendline chart or box-and-whiskers plot to continue the tutorial.