December 23rd 2025

Festive Greetings from TESTA Analytical

During the last year we saw a major resurgence of interest in optimised detectors for GPC/SEC. Today, TESTA Analytical is the only independent company with the chromatographic expertise and experience to support polymer, protein and polysaccharide chemists as well as to partner with GPC instrument manufacturers to deliver high performance multi detector system. When the focus of your investigation is not limited to molecular weights but you need to delve deeper into understanding the physical structure of a compound then our Differential Refractive Index (DRI), Multi-Angle Light Scattering (MALS) and Viscometer detectors can make all the difference. We would like to thank everyone for your continued interest in TESTA products and application solutions and wish you a very Merry Christmas with good health and prosperity in 2026. Relying on ‘soft’ polymeric particles to separate samples - GPC/SEC Columns are commonly prone to pressure instability. Each sample injection creates a pressure “shock” to the columns. A sudden change in flow rate when the injector valve switches from one position to the other (and for a fraction of a second when the passage of eluent is fully blocked) is the true reason for the pressure shock. While many believe GPC/SEC columns to be capable of absorbing this without experiencing any permanent damage, over time the accumulated effect of this affect risks compressing the separation media thereby creating a void volume at the head of the column. Continuous monitoring of flow in your GPC/SEC system, to ensure exact flowrate is rapidly reached after every switch of the injector valve, provides you with early detection of column compression and elimination of the consequent inaccurate results.

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In the Press: Complete and accurate characterization of macromolecules.

Many thanks to the editorial team at LCGC. They recently reported how if your investigation is not limited to molecular weights but needs to delve deeper into understanding the physical structure of a compound then the powerful combination of Differential Refractive Index (DRI), Multi-Angle Light Scattering (MALS) and Viscometer provided by our Trinity GPC/SEC triple detector is simply unbeatable.

FAQ: How do I keep my flowmeters clean and free of biofilms?

A: Cleanliness in precise liquid flow measurement isn’t just good practice, it’s critical. A biofilm is a complex matrix of microorganisms that can form on wet surfaces over time. A very thin layer of biofilm inside a flowmeter can drastically reduce sensor sensitivity, alter readings, and reduce sensor life. To maintain the reliability of your flowmeter and keep readings precise we recommend you follow these 3 simple steps:
1. Washing your flowmeter - use sterile, deionized or reverse osmosis water to minimize microbial growth.
2. Clean frequently – use a solution of 70% isopropyl alcohol (IPA) and water OR 0.1 M NaOH solution. Both are effective in removing organic residues. After cleaning, flush your system with water thoroughly.
3. Correct flowmeter sensor storage – when not in use for longer periods – store the flowmeter sensor filled with isopropanol. Do not use water as this promotes biofilm build up, even when the sensor is not running.

Why measured dn/dc is vital for accurate determination of Molecular Weight.

In most molecular weight determinations, the major source of error or inaccuracy is often related to sample preparation. In the case of GPC/SEC MALS protocols, both concentration and absolute injection volume need to be known with high accuracy. Any error in these values will directly affect the accuracy of molecular weight. In the case of a Goniometer system, all sample concentrations used in the calibration must be prepared with highest accuracy. Filtration must not modify to any extent the sample or its concentration. Providing these prerequisites are fulfilled, it is not uncommon for users to trust the determined molecular weights. Unfortunately, this overlooks the importance and impact of a sample and solvent specific parameter: the specific refractive increment index - dn/dc.