Particle Size Range for Zeta-Potential Measurements with the Litesizer 500

The Litesizer™ 500 can measure the zeta potential of particles ranging in size from 3.8 nm to 100 μm. Here, these specifications are verified by zeta potential measurements of a polystyrene latex standard and of a lysozyme solution.

Zeta potential is a key indicator of the stability of colloidal dispersions. For the Litesizer™ 500, the minimum size (diameter) specification for zeta potential measurement is 3.8 nm and the maximum size (diameter) specification is 100 μm. In this Application Report, these specifications are demonstrated by zeta potential measurements performed on a polystyrene latex standard and a lysozyme solution, respectively.

The Litesizer™ 500 contains a patented technology called continuously monitored PALS (cmPALS). Phase-analysis light scattering (PALS) is a well-known method for evaluating laser Doppler electrophoresis measurements. PALS greatly improves the sensitivity of these measurements, but it does have a significant limitation; namely, the non-linearity of the modulator. Such non-linearity means that measurements are only reliable when the modulator is restricted to small movements, which means short measuring intervals. The cmPALS technology overcomes this limitation, so that the modulator can make large movements and still provide reliable measurements, which leads to greater sensitivity and stability of the laser Doppler electrophoresis measurements. This means that meaningful results can be obtained with shorter measurement times and lower applied electric fields.

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