I need to make a flavonoid-enriched extract from Plectranthus amboinicus through the partitioning technique using solvent extraction. I'll be using 80% methanol, petroleum ether, chloroform, and ethyl acetate, and then the final product will be lyophilized. May I know if DMSO is the best diluent to be used if it will be subjected to MTT assay? Another question is that I need to state the solvent used during extraction. What will I declare?