Hi Uma,

0.5 McFarland is consistent with around 150 million bacterial cells, e.g. E. coli determined at 600 nm. If you know the cfu/ml in your sample and if you determine the absorbance at 600 nm for your microorganism then you can adjust the amount of viable cells per ml to 150 million cells which should reflect a McFarland standard of 0.5.

Regards,

Alec

Uma, Hi!

You mean colorimeter and not calorimeter. Colorimeter measures colour using broad-band filters. Calorimeter measures heat/energy in calories. Spectrophotometer, forms spectrum of uv-vis-IR range and measures absorption of monochromatic light.

Thanks for your response Mr. Rakesh, and Mr. Alexander. Mr. Alexander, you meant to say that if I can set 0.5 OD at 600nm is almost as same as 0.5 Mc Farland.