I want to test the antifungal activity of a vegetable extract with poisoned medium technique in PDA; i have 100 ml of the vegetable extract at 1000 ppm; and i want test 200 ppm, 100 ppm, 50 ppm, 25 ppm and 15 ppm; i want prepare 100 ml of PDA with each concentration. So according my calculation, i need make the next:
200 ppm = Add 20 ml of vegetable extract in 80 ml of PDA
100 ppm = Add 10 ml of vegetable extract in 90 ml of PDA
50 ppm = Add 5 ml of vegetable extract in 95 ml of PDA
25 ppm = Add 2.5 ml of vegetable extract in 97.5 ml of PDA
12.5 ppm = Add 1.2 ml of vegetable extract in 98.8 ml of PDA
So, my question is... are my caulculations right? thanks and regards.
Yes Marco Antonio Tucuch Pérez , your calculations are corrected. I have a doubt above you ask for 15ppm and calculating for 12.5 ppm. Why so? Well your calculation for 12.5ppm is half correct adding 1.25 ml of plant extract and homogenizing into 98.75ml PDA will make it more accurate. By adding 1.2ml plant extract and 98.8 it will make 12ppm only.
When you have your stock solution of 1000 ppm (Ci =initial concentration) of vegetable extract , just apply each time the formula of the dilution low (CiVi =CfVf) , and then calculate the the initial volume (Vi= CfVf/Ci) of the vegetable extrat, that you need to take, and complete the volume to 100 mL with PDA.
ya all are ok except the last one, to be more appropriate you make it 1.25 mL instead of 1.2 mL vegetable extract and 98.75 mL PDA instead of 98.8 mL.
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