Content Handbook F

Outline of method

The method is broadly similar to that used to determine the suspensibility of concentrates (MT 161), except that it employs only one inversion and a 5 min standing time. It involves preparing 250 ml of a mixture of formulation and water, mixed with only one inversion of the measuring cylinder. After standing under defined conditions the top nine-tenths is removed, and the remaining tenth assayed chemically, gravimetrically or by solvent extraction. The spontaneity of dispersion is readily calculated.

 
Scope

The method is suitable for aqueous suspension concentrates (SC) which are substantially diluted with water before use, and which contain only one suspended active ingredient. In some cases the method may be extended to concentrates containing two or more suspended active ingredients (see below).
Although the method gives reasonably consistent results, great care must be exercised in the interpretation of the results as the relationship between the measured spontaneity and the suitability or otherwise in field use, depends on the application equipment and its degree of agitation.