I want to add I absotely hate the nanodrop. We've had a demo for it, and found the readouts to be very unreliable. Fluctuations of 20% and more. Just leaving the same drop in and measuring the sample multiple times gives different values (going in both directions, so not only due to evaportations). Sure, it's easy and fast, and maybe good to have a rough idea about your protein concentration, but I would never want to use it for exact measurements such as needed for e.g. a CD or an ITC instrument. I've heard other labs in our department have similar issues. We've also had a demo for the Nanovue from GE Healthcare: same issues - very large fluctuations from one sample to another. I suppose this is simply an inherent problem with small volumes...
Cheers Filip Van Petegm On Thu, Dec 4, 2008 at 12:48 PM, Patrick Loll <[EMAIL PROTECTED]> wrote: > At the risk of dragging this discussion even further afield from > crystallography: > How can you get realistic numbers for concentrated solutions using the > Nanodrop? I understand that the instrument reduces absorbance by using a > very short path length. However, I thought that in order for the > Beer-Lambert formalism to be applicable, the solution needs to be > sufficiently dilute so that the chance of molecules "shadowing" one another > is negligible. Isn't this condition violated for concentrated solutions > (even with short path lengths)? > > Pat > > On 4 Dec 2008, at 1:27 PM, Michael Giffin wrote: > > We also like the Nanodrop... > > > --------------------------------------------------------------------------------------- > > Patrick J. Loll, Ph. D. > > Professor of Biochemistry & Molecular Biology > > Director, Biochemistry Graduate Program > > Drexel University College of Medicine > > Room 10-102 New College Building > > 245 N. 15th St., Mailstop 497 > > Philadelphia, PA 19102-1192 USA > > > (215) 762-7706 > > [EMAIL PROTECTED] > > -- Filip Van Petegem, PhD Assistant Professor The University of British Columbia Dept. of Biochemistry and Molecular Biology 2350 Health Sciences Mall - Rm 2.356 Vancouver, V6T 1Z3 phone: +1 604 827 4267 email: [EMAIL PROTECTED] http://crg.ubc.ca/VanPetegem/
