VALIDATION OF A METHOD FOR PARTICLE-SIZE DETERMINATION BY LASER-LIGHTSCATTERING ANALYSIS

The laser light scattering analysis method allows a good reproducibili ty and a high measuring speed. Wet dispersion with ultrasound is requi red for sample preparation. With identical sonication time and perform ance, the measuring result depends upon whether treatment is performed in the sampler of the measuring unit or in a beaker. For improved wet ting properties of the model substance Lifibrol which is hardly solubl e in water, surfactant must be added to the dispersion medium. Surfact ant addition affects both the measuring result and the saturation of t he dispersion medium with sampling material; however, it makes no diff erence whether a sample dispersion prepared in a beaker is measured in individual parts or in total. Using Lifibrol as a model substance, th ese findings resulted in the development of a procedure for the sample preparation of hardly soluble substances for particle size determinat ion by means of laser light scattering analysis.