| Abstract: | The characterisation of emulsions at dilution rates greater than the 1:20 used in most international specifications for agrochemical formulations is becoming increasingly important. The internationally-agreed CIPAC MT 36.2 test depends upon the determination of the shift in bulk concentration between the upper and lower halves of an emulsion after a period of standing. An analytical method specific to the active ingredient is stipulated. This paper reports an investigation of the use of CIPAC MT 36.2 with an emulsifiable concentrate (EC)-soluble dye which allows a colorimetric finish. This new method should be applicable to almost all ECs, and uses less costly instrumentation than the standard method. It could therefore allow more convenient use of CIPAC MT 36.2 for formulation development purposes. The limitations and range of applicability of the new method are discussed. For ECs of poor spontaneity it is shown that emulsion stability is strongly influenced by the emulsification technique used. Techniques within the frame of CIPAC MT 36.2 have been discovered which give repeatable results for such ECs. |
