This is DCFDA for ROS quantification? We should use black opaque plates for this assay, as the DCFDA stain is light sensitive.

the multi well reader usually has a lens which focus into the medium or onto the bottom of the well. if you measure in adherent intact cells and focus to the bottom you get more scattered light and an increase in the background signal which is most likely higher in the transparent plates. If you measure a fixed endpoint of cell extracts you might want to focus into the medium, in this case the background might only be slightly higher in transparent plates but the well-to-well cross talk will be higher. Conclusion: black plates are better but if you do not have them you could try with the transparent ones. If you do not need to watch you cells you could also get full black plates which will be cheaper because fluorescence is read in reflection mode.

thanks Heiko Dussmann and Kanugala Sirisha for useful suggestions. i'm using adherent THP1 macrophages and pity is as a PhD student I don't have money to buy right kind of stuff

Use black opaque plates for this.