Submicron particle size distribution determination using light scattering and particle chromatography. Evaluation of the techniques and their application to on-line measurements

The capability of turbidimetry, dynamic light scattering, packed column chromatography, and capillary hydrodynamic chromatography to provide the full particle size distribution (PSD) or an average of the PSD of submicron particles has been investigated. Turbidimetry can provide the full PSD of suspensions of submicron spherical particles when the ratio of the refractive index of the particles to that of the medium is larger than 1.15. In any case a correct estimate of the weight or turbidity average of the PSD can be obtained. A controversy existed in the literature has been resolved. Dynamic light scattering is a powerful technique for the determination of bimodal distributions of submicron particles. Packed column chromatography provides a good resolution of the PSD for particles with diameter smaller than 250 nm. Capillary chromatography is capable of providing consistent results for routine quality analysis in a wide size range. The potential of the above techniques for on-line applications and control purposes is discussed. Results are shown from on-line application of dynamic light scattering to a pilot plant reactor for latex production.