Measuring height of the signal at specified time

[mkawatasu]

Using Clarity software, can we pick up Height of data at a specified time?
For example:
When time course of enzymatic reaction is measured, amount of product is increasing with time. The amount of product is monitored with a flow through detector, and the detector analogue signal is output to Clarity. The user wants to know Height at just 3 min.
Could you please tell me whether it is possible or not?

[Daniel Mentlik]

Dear Miyako,
yes, it is possible, however as it is not a typical chromatographic application, it will require some specific settings. The way how to set the conditions for the height at a specified time is as follows:

• First, I assume that you want to measure the relative height value (compared to the height in the beginning of the analysis) and your detector cannot perform the autozero operation. I have simulated some data to show the procedure.
• Open the measured chromatogram and switch to the Integration tab. Change the values there so that the global threshold is very high (this will prevent normal integration of peaks in the resulting chromatogram) and global peak width is very small (this will allow adding narrow custom peaks in the next step).

  

• Add two peaks manually - one with the beginning at the time where the height should be counted (3,000 minutes in this case) and the second one somewhere very close to the chromatogram beginning, where the signal is the lowest (serves for determining the signal zero for subtraction). Minimal widths for these peaks is governed by previously set Global Peak Width parameter.
  Alternatively, when the detector is able to perform the autozero operation, the second peak is not necessary for the operation and the following procedure can also be simplified.
• Switch to the results tab and right-click on the Result Table. Select the Setup Columns... item.

  

• Configure the columns you want to see in the Result table to the right column, and those you do not want to see to the left column. For the operation, the Start Time and Start Value items are interesting from the current columns selection.
  If the detector is able to autozero itself, the setting is now complete, press the OK button to apply the settings. If it is not able to autozero itself, adding a custom column is necesarry.
  • Press the New Column button to open the Add User Column dialog.

    

  • Name your new column in the Title field, enter its units (the same as Start Value is saved in) and add the expression as shown in the picture.The second part of the value, the [Start Value]min, can be added from the Special Values listbox when the Start Value item is selected.
  • Click the OK button to add the column into the columns list.

    

  • Click the OK button to see the desired result. The desired height at the given time is shown in the Resp. column for the given row.

    

  Note that is is simply possible to add other peaks into the result table at different times (that is most simply done from the integration table), all of these "peaks" will have the height for them correctly counted.
• Now, transfer the integration parameters from the chromatogram to the template method, as usual.