Preventing the Jetstream effect in HPLC flow measurements.

Determination of flow rate in HPLC systems using non-invasive flowmeters is well documented. However, a problem arises when a phenomenon known as “Jetstream” occurs. This effect can occur due to an abrupt change in tubing ID. A sudden change from a narrow bore to a significantly larger bore will result in a faster “core stream” in the larger ID tubing but leave the liquid layers closer to the wall of the tube practically unperturbed. The Jetstream effect will affect the velocity profile of laminar flow and create disturbances which affect accurate measurement of HPLC flow rate. A new TESTA Analytical tech note describes this effect and describes a methodology for avoiding the Jetstream effect in HPLC flow measurements.

April 17th 2024

Powerful triple detector for GPC/SEC.

Our popular COMBO-ONE (DRI / Viscometer) and COMBO-TWO (DRI / MALS) combination detectors offer significant advantages over conventional GPC/SEC detectors, offering absolute molecular weights in one case and making universal calibration available in the second case. However, when the focus of your investigation is not limited to molecular weights but needs to get deeper into understanding the physical structure of a compound then our Trinity combination of DRI – MALS- Viscometer is simply unbeatable. The Trinity detector delivers absolute values for molecular weights plus absolute intrinsic viscosity and precise Mark-Howink coefficient data enabling you to unlock information about both chain flexibility and molecular density. As a result, your determination of macromolecular branching can be based on solid data rather than assumed or projected data, opening the way to a deeper understanding of your material under study.

Interested in triple detection?

Ultra stable GPC combo detector.

Is GPC detector stability a limiting factor in unlocking the molecular weight, structure or conformation of your polymer, protein, or advanced material? The outstanding stability of our COMBO-TWO detector package is an advanced analytical solution for high-resolution GPC applications which can have separation times of up to one hour. Combining a high-performance 7-angle Multi-Angle Light Scattering (MALS) and an ultra-stable Differential Refractive Index (DRI) detector that operate at the same wavelength with minimal delay volume, COMBO–TWO delivers exceptional results.

Patent granted for revolutionary viscometer design.

The German Patent Office has recently granted TESTA Analytical a patent for an advanced differential viscometer design that has the potential to revolutionize GPC/SEC application measurements. The novel viscometer design avoids the use of delicate pressure transducers for detection as used by all instruments currently available on the market. Instead, viscosity is directly derived from an accurate and precise measurement of flow in the two branches of the differential bridge. This patented technique results in a more rugged design eliminating the possibility of pressure peaks that may destroy a sensor. Coupled with outstanding sensitivity, compatibility with almost all solvents used in GPC/SEC and a wide dynamic range, this new design sets a new benchmark for this widely used technique.