Particle Characterization
Top 10 Wet Method Development Tips
- Design every method for maximum precision: repeatability and reproducibility.
- Study different sampling techniques to help minimize error. This is particularly important for materials with small outlier populations.
- Choose a solvent which has negligible reactivity with the material, wets the material without requiring copious surfactant, has a viscosity which can be pumped in the analyzer, and has a refractive index different than the material.
- If surfactant is required to help wet a powder, use as little as possible to minimize bubbling. If bubbles form, use low power internal ultrasonics to remove them during measurement.
- Too much material has been added to the analyzer when a new sub-100 nm population appears in the particle size distribution. This is caused by multiple scattering and can be avoided by adding less material (higher %Transmittance).
- Choose a refractive index by studying references (i.e. CRC Handbook), applying known information about the material, or, if no information is available, by minimizing the R-parameter.
- Refractive index (RI) affects the accuracy of the particle size distribution, but has a much smaller effect on the analyzer's ability to detect changes to that distribution. In practice, even an incorrect RI can be used to successfully monitor the quality of a material or process.
- Study the effect of ultrasound on the material. The real-time PSD display indicates when the material has been fully dispersed by ultrasound.
- Evaluate the method's robustness by calculating the coefficient of variation for the D10, D50, and D90 values across a minimum of three measurement results. The LA-960 automatically makes these calculations.
- Use the LA-960 Method Expert to automate and guide this important process.
LA-960 Education & Support Resources
LA-960 Product Page
