Trouble finding DNA concentration on Spec..

[Charles A Miller]

Hello again,
	I am am having trouble determining DNA concentrations on a 
spectrophotometer. When I measure the UV absorbance, I consistantly get 0 or
even a negative number when it is obvious through gel electrophoresis of
the supercoiled plasmid that there is plently of DNA. I am doing a 1 in
1000 dilution, which has worked before. My first concerns are that the spec
may be out of whack or that the quartz cuvettes may be dirty (we only have 
two). I know some people have used them to measure the OD of cell cultures
as well as proteins. Is there some way I can stringently wash these 
(in acid?) in order to clean away any residues? I would like to rule this out
before sending for the spec repair-person or buying new cuvettes.

Thanks fot you help in advance!

Chuck Miller
oravaxcm at world.std.com