Broad on Narrow Calibration

This method first requires the calibration of the column with a series of Narrow Standards and then a calibration with a Broad Standard with known Mn and Mw. It relies on a principle that Narrow Standards are used to characterize the shape of the calibration curve, while the Broad Standard is then run to compute suitable K and Alpha using numeric Newton method. Accuracy of Mn and Mw values calculated is about 1 e-5 compared to Mn and Mw values documented for the standard.

GPC Calibration (Broad on Narrow)

After selecting the calibration type, a narrow standard chromatogram can be opened. The Add All Narrow Peaks icon will transfer all integrated peaks data to the Calibration Summary Table, setting a new standard number for each standard chromatogram opened and creating a new line for each peak in the standard. The Add Narrow Peak icon will perform this operation peak by peak.

For multi-signal standards the Set RT To All Narrow Peaks icon is used for transferring the RT on subsequent signals to calibration for peaks where RT is not used. Operation is performed only for peaks with Std. No. value equal to current Std. No. indicated on the Window toolbar of the Calibration window. This command can also be used for recalibration by selected standard. In this case RT of standard peak must match Std. No. values as described and also match Recalibration Search Window of peak being recalibrated (for more details see also chapter GPC Calibration Options). The Set RT To Narrow Peak performs this operation peak by peak.

Broad Standard chromatogram can be opened next and Mn and Mw values should be entered. The Set Broad Peak icon will compute desired K and Alpha values and display them in appropriate input boxes.

The K Alpha Status area informs whether K and Alpha values are recalculated properly after last operation in the GPC Calibration. If the Broad Peak was set and the recalculation was performed without an error, the status is marked as OK. Otherwise a description is displayed in case the Broad Peak was not set or the computation of narrow calibration failed.