Micromeritics of granular pharmaceutical solids II. Factors involved in the sieving of pharmaceutical granules
✍ Scribed by Dale E. Fonner Jr.; Gilbert S. Banker; James Swarbrick
- Publisher
- John Wiley and Sons
- Year
- 1966
- Tongue
- English
- Weight
- 478 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0022-3549
No coin nor oath required. For personal study only.
✦ Synopsis
This report deals with basic studies concerned with the use of sieving as an accurate means of classifying granular pharmaceutical solids. Attention was focused on the effects of sieve shaker speed, initial load and particle size distribution of the granulation on the rate of particle size reduction and the cumulative per cent of material passing a sieve. The size and concentration of the smaller-than-mesh particles were shown to exert a profound influence on the equilibrium time of a sieve. Using a nest of sieves, an equilibrium time technique was developed to obtain the particle size distribution and permit calculation of various statistical parameters dependent o n the observance of the log-normal law. An equilibrium time procedure such as developed here permits the quantitative classification of granular pharmaceutical solids by sieving, with a better assurance that separatio: has been achieved with the minimum of attrition.
HERE ARE few reports in the literature con-Tcerning the sieving of granular pharmaceutical solids for the purposes of classification or size analysis. It would appear that, in the past, such important considerations as size of the initial load, the sieve shaker speed, time of sieving, and the hardness, particle size distribution, and shape of the material being sieved have either been left to chance or substantially neglected. Such fundamental parameters as the type of particle size distribution and the magnitude of various statistical diameters on a weight or count basis have also not been applied to pharmaceutical granulations.
Since sieving is the easiest technique available for classifying particles in the size range of granular pharmaceutical solids, it finds wide industrial application. However, sieving errors can arise from a number of different variables. According to Herdan (l), the most predominant are variations in sieve loading, duration of sieving, random orientation of particles, fluctuation through sampling, errors of observation and experiment, and the effect of different equipment and operations. Consequently, if sieving is to be applied as an accurate, quantitative technique for classification, i t is necessary to obtain more information as to the effect of the parameters previously enumerated on both the sieving process and the particle size distributions obtained.
Whitby (2) has carried out an extensive study of the physical laws which govern the sieving of fine particles. It was shown that the sieving curve under nonsteady-state conditions can be divided into two distinctly different regions, with