This is a recording of a webinar I gave on How To Measure Zeta Potential More Confidently.
I show you how you can maximize the confidence in your measurements - and their interpretation - needed for robust decision making.
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TRANSCRIPT
Optically concentrated samples.
Question: “How can we study concentrated samples without diluting?”
Realistically? You can’t using electrophoretic light scattering. Other techniques exist such as electrokinetic sonic amplitude (ESA).
Question: “If we reduce the gap between the electrodes, can it be a solution to study concentrated samples?”
No. But it is a solution to study high salt concentration samples and nonpolar samples. In both case, it’s because it allows a small voltage to be used to generate the same electric field as with other cells such as the folded capillary.
Question: “Most of the ELS instruments use forward scattering. If we use backscattering to study the concentrated samples, will it be possible to avoid peak broadening?”
Backscattering is used for particle sizing by dynamic light scattering, DLS. In backscattering mode, the instrument looks at light scattered from randomly-moving particles close to the cuvette wall on the same face as the incident light. This means there is minimal chance of multiple scattering (the cause of peak broadening). Electrophoretic light scattering looks at the particle motion between the electrodes in the center of the cuvette. For a concentrated sample, the incident laser will almost certainly undergo multiple scattering even before it reaches the center. The scattered light will suffer. All commercial instruments use the so-called reference beam configuration. My original PALS instrument uses the crossed-beam configuration which is immune to multiple scattering. As long as light can get through the sample, it can be analyzed.
Question: “How much should we dilute the samples?”
A very good question with a fairly simple answer!
