Nanodrop machine error message when measuring plasmid DNA concentration - (May/16/2014 )

This was the first time I've encountered our Nanodrop machine pop up an error message when I was reading a particular plasmid DNA sample (from a Miniprep). The message goes something like this: "Check for bubbles, contaminants etc".  Other samples ran fine and it's only this one particular sample which gives this error message. What could be the cause of this? 

I've checked and there's absolutely no bubbles or large contaminants.

Its just a bad sample with low amounts of dna and lots of contamination.

Normally when you shake the sample, pipette up and down a few times and then load 2µl you can sometimes get a measurement.. but its a bad sample anyway...

(the bubbles part: can be that you also just placed the drop in a "bad way", but most often its just the sample itself that is very bad)

pito on Fri May 16 07:05:25 2014 said:

Its just a bad sample with low amounts of dna and lots of contamination.

Normally when you shake the sample, pipette up and down a few times and then load 2µl you can sometimes get a measurement.. but its a bad sample anyway...

 

(the bubbles part: can be that you also just placed the drop in a "bad way", but most often its just the sample itself that is very bad)

What contaminants can we possibly get from a plasmid miniprep? Maybe some bacterial protein?

science noob on Fri May 16 12:23:04 2014 said:

 

pito on Fri May 16 07:05:25 2014 said:

Its just a bad sample with low amounts of dna and lots of contamination.

Normally when you shake the sample, pipette up and down a few times and then load 2µl you can sometimes get a measurement.. but its a bad sample anyway...

 

(the bubbles part: can be that you also just placed the drop in a "bad way", but most often its just the sample itself that is very bad)

 

What contaminants can we possibly get from a plasmid miniprep? Maybe some bacterial protein?

 

just "dirt", it can be anything... if something went wrong with the filter (in the tube) , organic matter, ... or the media you used (not removed enough) or just that you don't have enough plasmids (bad selection)..

And some proteins yes, but that should not be a problem normally.

Its hard to tell to be honest, these things just happen once in a while..

perhaps I should not have said: low amounts of DNA and lots of contamination... but low amounts of DNA and/or lots of contamination.