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CV assay and wavelength - (Aug/24/2013 )

Hello ! it is me again with another question!



I was working on a sample to test a particular treatment on bacteria over 48 hours using crystal violet assay.


After 24 hours, the sample was stained and measured at 595 nm.


By mistake, I did the 48 hours measurements of the sample at 570 nm!!! I am supposed to repeat that to be able to compare the effect after 24 hours vs 48 hours??? how significant could be the resulting OD when I changed the wavelength? any idea? I am googling but no success yet.


Appreciate your input...I hope there is a way to avoid repeating the experiment.


Google for crystal violet absorbance spectrum.


When you find a spectrum, you will see that 590 is the abs maximum (595 is just off the max), and 570 is on the shoulder of the peak.  570 should still work, but it will give a lower reading than 595 and will be more sensitive to variation due to minor changes in absorbance scaling the shape peak.