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.