Dear Mutenherwa -National Blood Service Zimbabwe,

we have been using the trypan blue exclusion in Neubauer chamber. After 3 hours of incubation with the potential toxic agent (you can vary the incubation time), 50 μL of Trypan’s Blue 0.4% was mixed with 50 μL of leucocytes and left to stand at room temperature for 5 minutes. Cell viability was determined microscopically (400x magnification) and expressed as number of viable cells divided by the total number of cells multiplied by 100. If you want to look at the simple methodology, I can send you some papers from our lab or you can look at those that are open access ( Biomed Res Int. 2013;2013:537279. doi: 10.1155/2013/537279.)

Regards

Joao

sorry, we have also used it with plant extracts (see Molecules. 2015 Dec 29;21(1):E2. doi: 10.3390/molecules21010002, it is open access). If you have any doubt, please, you can contact me.