Why is Flow Rate Important in GPC/SEC?

To obtain reliable data from your GPC/SEC instrument - each run should be related to a calibration curve obtained by measuring appropriate chromatographic standards. Calculations from GPC/SEC experiments are based on elution volume, which is a product of time and flow rate. As such, knowledge of GPC/SEC flow rate is of paramount importance as it is required to be constant over much longer periods of time than with HPLC separations.

To enable this, continuous monitoring of flow rate is the only reliable way to validate any GPC/SEC measurement and to make therefore sure, the current flow rate perfectly matches perfectly the flow rate used to create the calibration. It is noticeable that a variation of just 1% in flow rate will transform into an unacceptable error in calculating molecular weight as calibrations use log molecular weight versus elution volume.

Up to now, direct determination of flow rate has been limited to system validation using volumetric flowmeters, or, when monitoring was required, by use of Coriolis force flowmeters. While Volumetric flowmeters are known to be accurate, the method they use is relatively slow as measurement requires that a known volume must be filled and time difference must be detected in order to obtain a single data value. As such, volumetric flowmeters integrate over a relatively large volume (often several hundred microlitres) and are not suitable for delivering “real time” flow information. Coriolis Force flowmeter are well proven for providing very accurate flow measurement in HPLC systems but unfortunately are quite expensive, therefore again a limited solution.

Based around a thermal flow sensor the TESTA Analytical Liquid Chromatography Flowmeter has been proven to provide precise real-time monitoring of flow rate from GPC/SEC pump systems over extended periods of time (days / weeks).

To learn more about the Liquid Chromatography flowmeter please visit https://www.testa-analytical.com/gpc-sec-chromatography.html.