Comparison of conductivity-water content curve and visual methods for ascertaintation of the critical water content of O/W microemulsions formation

This study is to screen 23 blank O/W type microemulsion (ME) samples,that is 15 samples from our laboratory,and 8 samples from literatrue; compare the conductivity-water content curve (CWCC) method and visual method in determining the critical water content during O/W type MEs' formation,to analyze the deficiency and the feasibility of visual method and to exploxe scientific meanings of CWCC method in judging the critical water content of O/W type MEs during formation. The results show that there is a significant difference between the theoretical feasible CWCC method and visual method in determining the critical water content (P 0.001),and the results judged by conductivity is higher than that by eye-based water content. Therefore,this article firmly confirmed the shortcomings of visual method and suggested that the eye-base "critical water content" may falls into continuous ME stage during O/W MEs' formation. Further more,the CWCC method has theoretical feasibility and scientific meanings in determining the critical water content of O/W type MEs during formation.