We have an Ocean Optics USB-4000 unit in our lab. It does everything
from quantifying protein and nucleic acids, spectrophotometric
titrations, and metalloenzyme spectra at low volume/concentration. It's
not a toy, but a diode array spectrophotometer that has excellent S/N
and resolution. You can get a fully thermostatted unit for under $9000,
and an integrated, bulletproof non-thermostatted unit for under $3500
for UV and visible spectra. These units are also expandable and
re-configurable for different tasks. Beats the tar our of our HP diode
arrays, which were reliable, but not as capable. Cells from Starna run
from $150 (semimicro) to $250 (micro cells). We've never found them
difficult to clean. A vacuum-based cell cleaner is a good investment
that can clean and dry cells quickly.
--
Roger S. Rowlett
Professor
Colgate University Presidential Scholar
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
ofc: (315)-228-7395
fax: (315)-228-7935
email: [EMAIL PROTECTED]
David Roberts wrote:
Wow, that's like putting a pool in your backyard so you don't have to
pay the $3.00 admission every day (I'm kidding). In any event, Ocean
Optics has some very nice, small, and portable units that would run
around $3000 total. These connect to the USB port in a computer and
produce data that can be manipulated easily via any spreadsheet
manipulation program (open office, whatever). They are diode array,
and so they take quick, continuous spectrum. We use these in our intro
chem classes (sorry, small University, we can't afford the nanodrop)
and they work great. I believe it's the USB2000 if you go to the Ocean
Optics website.
And, for those who find cuvettes as expensive as a nanodrop system, you
can purchase polyacrylate ones that are good down to around 250 nm or
so. They are marketed as disposable, but work well with several
washings. They seem to be consistent from batch to batch, and we do
use them for simple 280's on things (though of course we pull out the
lock and key and get the quartz ones for those 2 special readings we
take every year).
Now, the specs you get are good and reliable (even though we use them
with undergrads). They are not high end Cary's, but I don't think you
need that sort of system for simple 280's. These detectors work as
good cheap fluorimeter sources as well with some modifications on the
light source (again, look around if that's something you are interested
in).
We use the Vernier system here, which allows us to connect
spectrophotometers (mentioned above), drop counters, pH probes,
temperature probes, and a whole variety of ion selective probes to a
computer for data collection using almost any device. It's quite nice
actually (vernier.com I believe).
Good luck with that
Dave
Michael Giffin wrote:
We also like the Nanodrop. Very fast, no cuvettes (breaking, washing,
cleaning, uh nitric acid bath anyone?), and the .ndv data file is a
delimited text file. Open in a text editor, copy and paste into a
spreadsheet, and you have a convenient record of all of your stocks,
including date, sample name, concentration, and full spectra.
It is expensive, but so are good cuvettes.
Mike
Michael Giffin
The Scripps Research Institute
Department of Molecular and Experimental Medicine
10550 North Torrey Pines Road, MEM-131
La Jolla, CA 92037
email: [EMAIL PROTECTED]
lab: 858-784-7758
On Thu, Dec 4, 2008 at 7:16 AM, Tim Gruene <[EMAIL PROTECTED]> wrote:
Dear all,
we would like to purchase a UV spectrometer for measuring protein
concentrations (280nm), and I would like to here your comments and
especially recommendations.
We don't need anything fancy, a small, fast device would be sufficient.
Tim
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
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