if i dissolve the test material in ethanol 70%, and use the ethanol as negative control ? What do you think about this study design?
Negative? For any kind of "control" it is entirely inappropriate. Ethanol is know to synergize efficacy even at low concetrations, and its ZOI may well cover the area of inhibtion of the putative antimicrobial.
Trying to shoe horn insoluble material into an assay that demands solubulity is also entrely inappropriate and bad science.
Can the material used be dissolved in sterile distilled water, if possible, then use it as a negative control, in my opinion
The ethanolic extract of the tested plant dissolve in ethanol. And ethanol used as the negative control. Fortunately , ethanol showed negative result against the tested microorganism.
Because many question arise of how to use ethanol as negative, i just want some literature that either support :
1. Using ethanol as negative control
Or
2. The benifits of using ethanol as solvent for ethanolis extract