Viscosizer technology

The Viscosizer 200 incorporates two measurement techniques in a single instrument, and has a range of accessories to optimize handling and analysis of a variety of sample types.

Viscosity Analysis:

At a known constant pressure and temperature, the viscosity of a sample can be determined from the time it takes to travel between 2 points, relative to a reference sample of known viscosity. The Viscosizer 200 is based around a dual-pass microcapillary assembly. The capillary contains two windows, at each of which UV absorbance of the passing sample is analyzed using a UV area imaging detector. Poiseuille’s Law is employed within the Viscosizer 200 software and relies on input of data concerning the appearance of the sample at both windows to give an accurate, reproducible measurement of viscosity.

Traditional measurements of sample viscosity using a capillary-driven system have always relied on the time of transit between injection and arrival at a single capillary window. Because the exact time of injection can be difficult to pinpoint and may not be reproducible, significant errors in viscosity measurement can result. The Viscosizer 200 avoids this potential source of error by employing a unique two window microcapillary.

Size Analysis:

Measurement of the size of particles present in a sample is also dependent on changes detected in the profile of the sample as it passes through the two microcapillary windows. In this case, Taylor Dispersion Analysis is used to analyze how the sample peak profile broadens between Window 1 and Window 2. As the sample moves through the capillary, diffusion of particles causes broadening of the peak, but this broadening is also tempered by transverse diffusion. The smaller the particles present, the more rapidly transverse diffusion occurs, resulting in a narrow peak. When larger particles are present, transverse diffusion occurs less rapidly, resulting in a broader peak. The change in peak breadth between the two windows is used to calculate the hydrodynamic radius of the particles of interest.

The Viscosizer 200 has interchangeable UV filters which allow user selectivity of the wavelength of interest for a particular sample. Any sample can be analyzed quickly and accurately, as long as it contains a UV chromophore. In addition, samples within complex formulations or matrices may be analyzed easily against a reference sample.

The Viscosizer 200 software is intuitive and feature-rich, based on a batch analysis format. Expert advice is provided via an integrated user miniguide.