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Oil-water emulsions: Particle size distributions from elastic light scattering data
Ist Teil von
Journal of colloid and interface science, 1989, Vol.127 (1), p.147-155
Ort / Verlag
San Diego, CA: Elsevier Inc
Erscheinungsjahr
1989
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals
Beschreibungen/Notizen
Particle size distributions are important quality criteria for pharmaceutical emulsions. Fat emulsions for intravenous administration should have a typical particle size of a few hundred nanometers and not overshoot an upper size limit of 2 μm. Particles with a higher diameter, suspected to cause adverse reactions (emboli), can be found in a phase contrast microscope. Our method uses elastic light scattering, i.e., the angular dependent scattering intensity to size particles in the range of 100 nm up to several micrometers. The advantage of this method compared with quasi-elastic light scattering is the higher resolution due to a higher information content of the experiment (much lower condition numbers of the matrix). It takes into account the actual relative refractive index and uses the Lorenz-Mie theory as a basis of the inversion procedure. This yields accurate number and intensity distributions, defined as the relative number of particles and the relative scattering intensity in the interval
R and
R +
dR. Since the scattering intensity is roughly proportional to the sixth power of the radius, larger particles can be found in the intensity distribution even if their number is in the ppm range. We can therefore supply the producer with two important and well-defined kinds of information: (a) the number distribution, which provides the parameters of the particles like mean, standard deviation, and skewness; (b) the intensity distribution, which is a very sensitive control for undesired large particles.