Particle sizers are used to determine the size of particles or molecules in liquids or gases. One of the most common methods for determining particle size in liquids is dynamic light scattering (DLS). A laser beam is directed onto a dispersed sample and the time-dependent intensity fluctuations of the scattered light are analysed. The diffusion speed can be determined from the correlation function of these fluctuations, from which the hydrodynamic diameter of the particles is calculated. The DLS method therefore enables fast, non-contact and reproducible measurement of even the smallest particles in the nanometre range.
The High Performance Particle Sizer (HPPS) from Malvern is a precise particle sizer for analysing molecules and particles in solutions or dispersions, which is based on the principle of dynamic light scattering (DLS).
The HPPS combines optical precision with modern software control and thus enables reproducible and high-resolution measurement results. The centrepiece of the system is an optical unit with a helium-neon laser with a wavelength of 632.8 nm and a maximum power of 5 mW. The sample is filled into a cuvette, inserted into the cuvette holder and automatically positioned to ensure the optimum measurement geometry. The HPPS software controls the entire measurement process via the connected computer and analyses the data in real time. The measurement results are displayed in the form of intensity, volume or numerical distributions and provide characteristic parameters such as the Z-mean size and the polydispersity index. These key figures provide information about the average particle diameter and the homogeneity of the particle distribution. The device enables measurements in a temperature range from 10 to 55°C, which is why it can be used to analyse thermally sensitive or temperature-dependent systems.
The accuracy of the measurement results depends largely on the quality of the sample preparation. A suitable concentration of particles, filtration of the dispersant and the avoidance of air bubbles or aggregates are crucial for reliable analysis. The HPPS covers a wide measuring range and can analyse both highly concentrated and highly diluted samples.
With its combination of precision, ease of use and reliability, the Malvern HPPS is a versatile analytical instrument for particle sizing in research and industry. It enables fast and reproducible characterisation of particles and molecules over a wide range of sizes and concentrations.
