Hi, i am a postgrad student who are currently doing malaria research and i will do Beta hematin inhibition assay. i would like to ask what is the suitable solvent used for the dilution of the extracts and standard drug? and i've tried to run the experiment and i got negative digits after i did the calculation by using the formula given which is

f = (Acontrol -Asample)/ (Acontrol –Amin)

% of inhibition = (1-f) x 100

Acontrol is the absorbance of the heme with the absence of parasite lysate or lipid extract or an antimalarial compounds at 405nm while Asample represents the absorbance of the heme in the presence of both parasite lysate or lipid extract and crude extracts or major compounds. Amin is the absorbance of the heme with parasite lysate or lipid extract in the absence of an antimalarial compounds at 405nm. my extracts mostly got colours and the absorbance of the extracts is higher than the control. am i following a right formula or is there's any other formula that i can use? Thank you in advance.