you dont need a solvent for test enan. Best to purchase a graduated cylinder/beaker to measure final solution. add powder(paste) to beaker, then fill till you reach 40ml. you can make it 400mg/ml if you want, make it what ever strength you want to. it still dont need a solvent. if you wanna BA for partial sterility protection then by all means add it. Baking it for an hour on 250 after filtering is a good idea also. good luck