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Quantifying plasmid DNA - Nanodrop and Qubit (Invitrogen) suck! (Mar/28/2009 )

Does anyone know a decent equipment that would be able to quantify plasmid DNA better than the Nanodrop? I don't want to waste too much sample and was hoping that the Nanodrop might do an OK job. Turned out that when I use the Nanodrop it always tells me that my samples are of low concentration, but when I run them on gel they show up has having really bright bands! So I now have to linearize my plasmids, run them on a gel and roughly quantify them using the High Mass Ladder (Invitrogen), which takes so much time! Does anyone have a better idea? The Invitrogen Qubit also sucks at quantifying plasmid DNA too.



Probably your Nanodrop has to be recalibrated. Or do you have a special buffer to keep your plasmids in?

For me it always works perfectly. For DNA aswell as for RNA.


U might want to mix the solution properly prior to doing nanodrop. taking it from just the surface sometimes gave low reading. from my experience it' s better to figner vortex and then pipet few times b4 taking the sample for measurement.