How to measure DHA Data for the first time

Step 1

See the chapter "Specification" for an overview of specifications of supported DHA norms. For perfect and valid results, it is necessary to prepare your instrument and method according to the specification of a particular norm. Otherwise, the data you are about to measure will be useless.

Step 2

In the System Configuration window (menu Clarity - System…), select the DHA in the Instrument Type Setting dialog, for example on the Instrument 1. For more details see also chapter Installation.

Step 3

After saving and closing the System Configuration window, open the appropriate Instrument. Now, create a new project: in the Login Dialog, select <New Project> in the Select Project drop-down list and click the OK button. In the Create Project or Save as... dialog, name your new project and click OK.

Step 4

Now, you have to create the DHA Calibration according to the selected norm and your instrument. DHA Calibration is a Calibration that contains parameters required for the DHA calculations. Proceed as follows:

Measure the known n-Paraffins samples. It is best to measure all the possible n-Paraffins to have an exact interpolation of the calculated Retention indexes. In order to create the full calibration with all n-Paraffins, it is necessary to measure two standards (first for C1-C4 and then for C5-C15). As a minimum, you have to use C5-C11, however, extrapolations usually do not work.

Open the measured chromatogram with integrated C5-C15 n-Alkanes, and in the DHA Settings, select the norm you intend to use and click the Create DHA Calibration button. The displayed dialog automatically fills the n-Alkanes starting from C5. If you have measured the Retention times of C1-C4 n-Paraffins beforehand, fill them out manually based on the corresponding chromatogram.

Save the created DHA Calibration. Note that in this type of calibration, the option Retention Indexes use Log. Interpolation with Unretained Peak in the Calibration Options is automatically enabled.

Step 5

Now, you can prepare a method for measuring the unknown data.

If you want to link the DHA Calibration to your measured chromatograms automatically, select the one created in Step 4 using the Set… button in the Method Setup - Calculation window below the Calibration (Peak Table) field.

Step 6

Measure the unknown data using the Method created in the previous step.

Step 6

In the Chromatogram window - DHA tab, you can find the DHA Results and DHA Group Results subtabs containing the DHA Calculations.

Finally, you can continue to the chapter "How to print or export results from the DHA Extension".