The new Viscosizer 200 from Malvern Instruments is the latest product to reach commercialization as a result of Malvern’s highly focused Bioscience Development Initiative. Designed primarily to help solve key analytical challenges at the preformulation stage of pharmaceutical, and particularly biopharmaceutical, development, the automated Viscosizer 200 delivers viscosity and molecular size data on UV-active samples, using volumes of less than 10 µL.
Measuring viscosity early in the development of biological formulations is critical in order to reduce the number of candidate failures during subsequent stages of development. The Viscosizer 200 has been engineered to meet early development screening requirements which demand automated measurement on extremely low sample volumes, which should ideally be recoverable, as well as operation at high sample concentrations under formulation conditions.
The temperature-controlled Viscosizer 200 measures viscosity from 0.9 cP to 120 cP and hydrodynamic radius from 0.2 nm to 100 nm, in samples at concentrations from 0.1 mg/mL to >300 mg/mL. Its integrated carousel autosampler can be configured with a maximum of 45 vial positions.
The technology at the heart of the Viscosizer 200 is UV area imaging. This is used to monitor the time-dependent absorbance profile of UV-active samples such as proteins, peptides and other chromophore-containing molecules as they migrate through a microcapillary.
Capillary viscometry has long been used to determine viscosity from a simple measurement of time from injection to detector, but is subject to injection time errors that can result in significant errors in subsequent calculations. The Viscosizer 200 has a dual-pass capillary design whereby sample is detected at two windows along the capillary. This enables precise measurement of the transit time between windows and therefore of the sample’s viscosity relative to a reference, with demonstrable improvements over single-pass capillary systems.
For sizing analyses, as the sample migrates through the capillary, diffusion leads to broadening of the sample plug, a phenomenon countered by transverse diffusion: the smaller the molecule, the more rapid transverse diffusion and the less broadening of the peak. The Viscosizer 200 calculates mass-weighted mean hydrodynamic radius from the standard deviation of the sample profile at the two windows. UV wavelength selectivity means that the Viscosizer 200 can accurately measure the size of molecules of interest even within an excipient-laden formulation.
The Viscosizer 200 delivers to the demanding requirements of early biopharmaceutical development. It provides a unique analytical tool to support rapid understanding of the behavior of candidate molecules in various formulations, enabling important decisions on suitable formulations to be made as early as possible. The Viscosizer 200 also offers reliable size measurements for a variety of challenging applications in related fields.