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Particle Size Analysis through Static Multiple eLight Scattering

jul 19 2018

Particle size analysis is critical for characterizing the physiochemical properties of heterogenous solutions such as emulsions. It is important to not only measure the size of dispersed media (solid particles, droplets, nanobubbles) but also monitor their evolution. Thus, the measurement is best to be done in the native form, without dilution or mechanical stress to determine the accurate stability and ageing properties.

Conventional particle size analysis methods such as Dynamic Light Scattering (DLS) use invasive processing techniques to monitor dispersed nanoparticles. Stirring, diluting, or centrifugal mixing can provide access to quantifiable information about the nature of solutions but are unsuitable for determining the stability of dispersion state as they are subjected to external forces and remain in weak equilibrium with the dispersive media.

Turbiscan, based on Static Multiple Light Scattering (S-MLS) is the preferred method for particle size analysis of native form solutions. This post will explore the principles and advantages of the S-MLS technique in further detail:

The Principle of S-MLS Particle Size Analysis

S-MLS is an optical particle size analysis methodology that allows characterizing native state liquid dispersions in concentrated formats. Typically, concentrated emulsions and suspensions must be processed with diluting agents and mixed prior to analysis via laser diffraction or DLS. The mechanical agitation of mixing alters the equilibrium of dispersant particles and the dispersive fluid (as presented in our application note TS_SIZE_01). Diluting the mixture can also change the characteristics of the liquid phase, providing unrepresentative data regarding the native form properties of the solution.

Particle size analysis through S-MLS using Turbiscan provides accurate measurements of concentrated formulations without agitation or dilution. The interactions between particles in solution can therefore be more accurately assessed over time, providing extensive insights into the physiochemical characteristics of complex solutions.

Turbiscan® operates using a near-infrared light source (850 or 880 nanometers). The light source projects photons into the formula, which repeatedly scatter off particles or heterogenous droplets dispersed in the solution. Two synchronous photodetectors acquire the scattered photons to determine the transport mean free path of light through the sample, and the average distance between scattering media. The acquired sinals are respectively known as backscattering(BS) and transmission (T). Together they provide accurate particle size analysis over predetermined periods, allowing formulators to assess the evolution of particle size or volume fraction and characterize the stability of emulsions and their resistance to physical phenomena such as sedimentation and agglomeration.

S-MLS Particle Size Analysis with Formulaction

Formulaction is committed to innovation in the field of non-destructive analysis of increasingly complex formulations. We have developed Turbiscan range based on S-MLS to support the characterization of formulations (stability and particle size) for the cosmetic, pharmaceutical, food and beverage industries, and more.

The Turbiscan® is a robust system designed to measure the average particle size in concentrated solutions, using S-MLS technology to quantify the long-term stability of formulations without dilution or mechanical stress. This is established in accordance with ISO TR 13097, and can provide measurements relating to the actual dispersion state and the tendency towards agglomeration or flocculation.

If you would like any more information about performing particle size analysis with Formulaction equipment, please do not hesitate to contact us.

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