Dear colleagues:
A joust with the bureaucracy monster has been consuming my time for the
last two weeks, so the summary of responses to the question of
automated tube washing vs. disposables at high field is overdue.
Please accept my apologies. We still haven't decided what direction
we're going, but the responses have been helpful to us. I hope they
are useful to some of you as well. Thanks to all who replied,
Bill
Wm. R. Kearney, Ph.D.
Director
College of Medicine NMR Facility
58 EMRB
The University of Iowa
Iowa City, IA 52242
ph. (319) 335-6610
fax (319) 335-8049
william-kearney_at_uiowa.edu
Original question:
Dear AMMRLs:
I'd like to add a second request for info on tube cleaning. Does
anybody out there have wisdom to share on cleaning and drying 200 or so
tubes/day? The tubes will have assorted biogoo residues in them. We
are looking to do this with as little human intervention as possible.
Thanks in advance,
Bill Kearney
Response 1:
We wash this many tubes a day, using the Bruker Automated Tube Washer, and
have done so for about 8 years. Fantastic piece of kit, very robust. Will
cost you around $20K, I think.
http://www.bruker-biospin.com/nmr/products/autoclean.html
Response 2:
A note of caution about drying nmr tubes. If the drying is done at too
high a temperature, the tubes can be warped enough to cause problems for
the probe insert.
Response 3:
f you can tolerate them, the Norell XR-55 tubes are quite inexpensive,
~$2.75 each. Throw them away.
Response 4:
See
http://www.bruker-biospin.com/nmr/products/autoclean.html. A number of
pharmaceutical companies are using this device for just this purpose. It has
a high investment (~$16,000), but pays for itself inside a year or two.
Response 5:
200 tubes per day must require a sample changer and full automation.
We have gone to Wilmad disposables (HIP-7) for our basic organic
service. At $0.85 per tube it is less costly than spending 2 hrs a
week cleaning tubes. The quality is pretty good and we do not see much
difference between them and the 528-PP's at least with automation.
They are not the greatest, but they seem straight and consistent. We
never had a problem with spinning and have not had any insert problems
with our Bruker probes. We charge an extra $1 to all our runs to
offset our costs so we really do not see the added expense.
Response 6:
In my experience, cleaned tubes are more likely to break--causing
serious and possibly expensive problems for a high volume routine lab. We
use modern Norell "throw-away" tubes and avoid the recycling costs altogether.
Response 7:
Bruker sell an automated tube cleaner (I believe the part number
is BATW-60). It accommodates up to 60 tubes, and can also be adapted to
wash 3mm tubes as well as 5mm. 7" and 8" tubes can be accommodated. A
typical washing and drying cycle takes about 30 minutes, and uses up to
3 different solvents (e.g. acetone, ethanol and water) for washing.
The only problem is price - possibly ca. $30,000 if I remember
rightly. Also, it is made (and serviced) by the Bruker UK group, so
when it breaks down, service can be an issue, although the UK engineers
are very helpful for over-the-phone diagnosis and repair.
Response 8:
Fortunately, the chemists I support see tube washing as deeply sexy!
On the other hand, we are reviewing tubewashing with a view to moving
towards disposable NMR tubes for routine analyses!
Response 9:
Soak-em in concentrated HNO3 for a few days _en_masse_...it dissolves
almost all inorganics and hydrolyzes all organic/biogoo. The rinsing with H2O
and then acetone/drying might take some individual attention...
Response 10:
We have 5mm NMR tube washers at our facility. I believe they wash 50 or 100
at a time. I know Wilmad sells them, but I do not know the brand name. I
can get if you need it. It is fully automated, with variable wash solvents
and wash times. If you do not get the exact info you want form other
responses, just let me know and I can take a closer look at them.
Response 11:
We run about 30 starch analyses a week amoung other things in 5mm NMR tubes.
As soon as we finish a starch analysis, we empty the tube and fill it
with about a 5% solution of Cascade (bought at the grocery). We allow
the filled tubes to set in a jar 5% Cascade solution. For other
materials we empty the tube, rinse with acetone, DMF, or whatever it
takes to dissolve the residue, and then fill them with 5% Cascade.
After a day or two we empty the Cascade from the tubes and rinse with
water using a jet tube washer. That way we don't have any solids
left. We then empty the water from the tubes and oven dry them at 80C
for a few hrs.
Cascade and NMR tube detergent will leave a residue, if it is allowed
to dry on the glass surface. You must avoid this by keeping the whole
tube submerged.
I hope that this helps.
Response 12:
Buy the $1.00 to $0.50 tubes and pitch 'em!!
Unless you are really, reallllllly worried about line shape - they do just fine...
Response 13:
I would be really curious to hear what the others think about this
topic, as we are seriously considering a Italian device that is
relatively new on the market, and appears to handle 52 tubes at a time
via some sort of dual carousel mechanism, solvents, vacuum and so on,
but costs a good few bucks. (Around USD 20k or so.)
Response 13a:
Have a look at
http://www.labhut.com/NewFiles/Hta/Workstation_Overview.asp is the one
we are thinking about. It appears the device was designed for another
application, but it is its NMR tube cleaning capability we are keen on.
These guys are the marketing arm of the original Italian supplier,
http://www.hta-it.com/en/ht400w.htm. (Their English is a bit rough at
the edges, but the Product looks OK, and I see also 115v now days.)
Oddly enough I had another version touted to me this morning....This one
also looks interesting, in the sense it is using a Solvent distillation
principle, and appears to be a closed loop. All the others, including
this Italian job, use solvents that one has to hoof at the end of the
day. I will go and have a look at it early next week, as these guys are
keen we do the marketing for them. (They are one of our customers, and
Academics, with no interest in getting their hands dirty with sales, so
fair enough.) They claim to have applied for a Patent, so they at least
think there is a great future for their design. From what I can gather
so far it only does a tube as a time, but they claim it is expandable,
so we'll see.
Response 14:
Bruker sells a tube washer that should do the job. ... NNNN at
A.COMPANY has and uses one for his chemists' 3mm tubes.
Response 15:
I've had no trouble getting below 1 Hz using Wilmad HIP tubes at 500
MHz; haven't kept track of how much below, but I feel 0.8 Hz is
typical. I also favor running unspinning (even using high-end tubes)
if there are any big peaks in the spectrum.
Response 16:
Didn't take part in the first set of questions, but am interested in
the survey, so I'll chime in here.
Are there disposable tubes that work well at 800 MHz? If so, which
ones?
Cannot help with this question; would never have thought of using less
than a 528 quality tubes for 800 or higher.
How do lineshapes compare between your "usual" tubes and disposables at
500 MHz and below?
We use Wilmad 507s all the time on our 500s, including for 1H spectra.
There is a bit more difficulty with them with manual shimming
(non-axials) than with 528s, but they consistently do fine. I do not
recommend them, however, for water-suppression experiments; they
definitely do poorer than 528 or better.
We have used disposables (Wilmad's ECONOMY) tubes on the 500s, as I
have found them to be consistently fine at 360 and 300 MHz. Here, I
find a significant, but low, percentage (probably ~10%) of the time, we
have significant trouble with them in with getting good shims. I
therefore do not recommend their use here for the 500s; I strongly
advise students to transfer the sample to at least a 507 for the 500s.
We soak, rinse and dry 3mm tubes similar to 5mm tubes. I have never
used "disposables" at 3mm (didn't even know such were available). Be
very interested in hearing your responses, especially for 3mm tubes.
Response 17:
Ah, here we can add our 2c worth..... we too tout the disposables, and I
must admit they sell like hot cakes!!! A lot of our customers have high
field machines too, and use these disposables for the really cruddy or
'high volume' experiments, even at high fields.
If you think about it, you are almost certainly not spinning on the 800.
Wilmad's HIP-7 is only USD 85 for a 100. The tube is unmarked, and has a
ever so slightly thicker wall to make it more robust, or I say 'student
proof'. Just buy a single package, and try them out. I suspect you will
find them OK or better for whatever it is you want to run in a cheap
tube (i.e. just hoof it afterwards) and of course you can still use the
good ones for the really 'expensive' or 'long measuring time' samples.
My feeling is if one has a fancy sample worth a small fortune no one is
his right mind is going to stick it in a 85 cent tube, no matter how
good it is. However, there will almost certainly be cases where you do
not care about the sample, and consequently the tube, in which case 85
cents is just fine.
Response 19:
We use Wilmad HIP-8 tubes for our chemists' samples (mainly 300 &
400 MHz). Very occasionally we get one that won't give good shimming,
or is
a bit loose/tight in the spinner, but overall I'd say we're quite
pleased.
We get breakages in the probe if the slow drop air pressure is not
properly
regulated, but that's only fair.
Response 20:
I've used thousands of disposable tubes for ALL routine operations
since my early years at ... . I've used them at all field strengths up
to 600 MHz and on all models of spectrometers without ANY problems
(inside the magnet). Let me emphasize that these were ROUTINE studies,
only. All serious studies that needed ultimates in lineshape,
resolution and/or sensitivity have always been done in higher quality
tubes (not disposable in my hands) as per field strength.
The tricks include: 1) using a gauge that checks that the outer
diameter and bend of each disposable tube is within probe specs; 2)
don't spin these tubes; 3) don't necessarily expect perfect spectra.
The gauge is one we purchased some time ago from Wilmad. Others may
suffice. We don't spin because we don't have to spin to get reasonable
data. The new field control systems together with field mapping and
gradient shimming make this generally unnecessary. In fact, there are
fewer artifacts and cleaner spectra when you don't spin. Spinning can
introduce a wobble and aggravate problems with close probe tolerances.
We don't wash the tubes. Never been a problem for our samples (but it
might for you).
Our results with these tubes are excellent but not outstanding. That
has generally been good enough and outweighs all the other issues
involved (expense of cleaning, did we really get the tube clean,
solvent disposal, etc..).
Tubes cost $1.25 or so in bulk.
Received on Fri Mar 19 2004 - 09:23:56 MST