Hi,

 

How can I perform a 2-fold serial dilution in a microtitre plate for an MIC test ? (minimum inhibitory concentration test)

 

please help,

The way I do them is by adding 196 uL of media + 4 uL of your compound in solution to the first well and 100uL of media to the rest of the wells. I then take 100uL from the first, pipette that into the second and mix by pipetting up and down. I then pipette 100uL from that well and put that into the next one and so on until the last well has a total volume of 200uL and the rest, 100uL. I then discard 100uL from the last one and add 100uL of cell suspension to each well. By doing this, each well contains half the concentration of your compound as the one before it. You just need to make sure you do your math properly.

 

Also, multichannel pipettes are your friends. If you don't have one and you're doing a lot of these, I would invest.

The first step (and the actual volume) is variable, of course. Other than that hypervalent's approach is the common approach. One thing I would add is, depending on the required precision, to change the tips to avoid errors (some do not and it can lead to issues). With 1:2 dilution it is not that bad, but depending on the sensitivity of your assay and how precise you need to determine MIC, it is best to minimize simple technical errors.

Thank you everyone for your help, I have got it now

The way I do them is by adding 196 uL of media + 4 uL of your compound in solution to the first well and 100uL of media to the rest of the wells. I then take 100uL from the first, pipette that into the second and mix by pipetting up and down. I then pipette 100uL from that well and put that into the next one and so on until the last well has a total volume of 200uL and the rest, 100uL. I then discard 100uL from the last one and add 100uL of cell suspension to each well. By doing this, each well contains half the concentration of your compound as the one before it. You just need to make sure you do your math properly.

Also, multichannel pipettes are your friends. If you don't have one and you're doing a lot of these, I would invest.

 

Yes i will definetly be using a multi one !