Study highlights importance of real-time flow rate monitoring in GPC/SEC

A new technical study from Testa Analytical underscores the critical role of continuous flow rate monitoring in Gel Permeation Chromatography (GPC) and Size Exclusion Chromatography (SEC) experiments. Flow rate is a key parameter in liquid chromatography systems, influencing retention times and, ultimately, the reproducibility of results. This study showcases the Testa Analytical Liquid Chromatography Flowmeter as an invaluable tool for non-invasive, real-time flow rate measurement in GPC/SEC systems.

GPC and SEC are widely used for characterising both natural and synthetic polymers due to their straightforward design. These systems rely on a pump to drive solvent through the column, where the test sample is introduced. The resulting data is analysed using a calibration curve derived from reference standards with known molecular weight. The molecular weight of an unknown sample is determined based on its elution volume, which is matched to the corresponding value on the curve.

In the study, researchers examined the impact of a +/- 1% deviation in flow rate on the molecular weight determination of an unknown sample. This small variation, often caused by backpressure in typical GPC/SEC systems, is usually undetectable with onboard pump pressure transducers. The experiment involved running a sample after calibration, manually adjusting the flow rate, and repeating the process for a second sample using a viscosity detector and universal calibration.

Results showed that a 1% deviation in flow rate caused more than a 20% change in the calculated molecular weight. These findings highlight the importance of constant flow rate monitoring and the need to adjust chromatogram calculations accordingly.

Testa Analytical’s HPLC Flowmeter provides a solution for this challenge. It offers continuous, non-invasive flow rate monitoring, compatible with various solvents. The device, powered by a USB connection, features a high-resolution thermal flow sensor for precise measurements across a wide dynamic range. An intuitive PC-based app allows users to record and store flow rate data, with real-time data displayed on a built-in OLED screen.

For a copy of the full technical study, contact Testa Analytical.

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