Malvern: viscosity add-on for Zetasizer Nano
accessory for its Zetasizer Nano particle characterisation system
that should improve the ability of the instrument to study
emulsions and dispersions.
The SV-10 Vibro viscometer gives rapid, highly accurate viscosity measurements in the range 0.3 to 10,000 milliPascal second (mPa.s), according to Malvern, and is being marketed as a relatively low cost item.
The unit offers 1 per cent accuracy across the whole measurement range, and the data it generates can be used to enhance the accuracy of particle size measurements by dynamic light scattering, said Malvern. Used together, the SV-10 and the Zetasizer Nano are particularly useful for the characterisation of proteins in solution prior to crystallization.
Malvern launched the Zetasizer Nano, which measures particle size, zeta potential and molecular weight of nano-sized particles and molecules in one unit, in 2003. It is used in a range of applications, including DNA transfection, protein conformation and crystallisation studies, pharmaceutical formulation and water treatment.
The technique of dynamic light scattering determines particle size by observing the random movement of particles undergoing Brownian motion. As this behaviour is directly related to the viscosity of the fluid in which the particles are moving, inaccuracies in the measurement of viscosity translate directly into inaccuracies in particle size measurement.
The very high accuracy of the SV-10, even at the low viscosities typical of aqueous media, therefore makes it an invaluable accessory for dynamic light scattering systems," according to Malvern.
The SV-10 determines viscosity by measuring the current required by an electromagnetic drive to vibrate two gold paddles immersed in the sample at constant amplitude. The damping effect on the vibration due to the sample is related to its viscosity. The system takes around 15 seconds to stabilise, after which a continuous reading of viscosity is produced.
The use of gold plated sensors makes the unit compatible with all fluids and it is suitable for measurements in the temperature range 0 to 100oC.