I have recently started culturing different phytoplankton species in 24-well microplates and taking absorbance measurements using the microplate reader FLUOstar OMEGA. Surprisingly, OD data for all the species have been decreasing over the week, even though it was noticeable that the wells were getting greener and greener, which does not make sense. OD data seem fine when I use the 96-well microplate, so I supposed it had something to do with the 24-well new protocol (maybe the scanning feature, which was the only setting that was changed in the protocol). However, I tested an empty microplate under this new protocol, colouring in black some of the wells, and the results made sense, as OD data were higher in those that were coloured. I don’t know what can be causing this incongruity, can anyone come up with a possible reason??
Thank you very much,
Macarena Blanco
I am not familiar with this particular microplate reader. Can you give some information about the settings you were using? For example, at which wavelength/s did you measure absorbance?
Hi Sebastian,
I measured it at 450, 600 and 660nm, though I am mostly interested in the measurements at 660nm. Regarding scan settings: matrix scan (dimension 3x3, 15mm width and 10 flashes per scan point).
Dear Macarena,
As you did a new setting, are you still in OD units and not in transmission ?
Hi Claude,
I am still in OD units. However, I am now pretty sure that the problem was the diameter of the scanning, as I have changed it to 5 mm and the results are finally making more sense.
Thanks.
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