Regards,
Kurt
______________________________________________________________________
I am going to purchase a H,C,X triple resonance Z-gradient inverse probe
for our Bruker 500 MHz spectrometer. I have been looking at both Bruker
and Nalorac probes. Typically in the past, I would just go ahead and buy
a Bruker probe. I believe the Bruker probes are robust and easy to use.
Furthermore, I have not had many problems with most of my Bruker probes,
which makes the decision even more difficult. For the specific probe
that I am considering, I find that the Nalorac S/N spec and pricing is
somewhat better than Bruker's. However, I have a better comfort zone
with the Bruker probes since I have never used a Nalorac probe or had to
deal with Nalorac as an organization.
I guess what I would like to know is what are the experiences of others
that have used both Bruker and Nalorac probes, and what do they feel are
the pros and cons of a Bruker probe or a Nalorac probe. Additional
unknowns to me about Nalorac are things such as service, availabilty of
loaner probes, turnaround time for repairs, how do Nalorac personnel
work with you when you have a problem, etc. I know that I am looking at
a fairly new probe design, but I would like to get any replies that
discuss these issues or specifics about the pros and cons of this probe.
If there are many replies, I will consolidate them and e-mail them back.
Kurt,
______________________________________________________________________
We've had good luck with our Nalorac probes on a Varian Unity 500
(inverse triple H C N, and an H F dual). When the tuning became
flakey on one of the legs, it made a fast round trip with no
questions asked and worked fine again. But I do really like the
robust Bruker probes, and the digital tuning wands on the X channel
make it user friendly (We have an inverse H P X Z gradient on our DRX-400).
good luck with your new probe,
dave scott
iowa state university
515-294-4057
______________________________________________________________________
We have two instruments at Dexter, a Varian VXR-300 and a Unity Plus 500.
The 300 came with a Varian
5mm broadband probe, we subsequently purchased a Nalorac 10mm broadband
probe for this machine. This was back when Nalorac was just getting started.
I too was impressed with performance/price aspect. At that time,
sales/service support was very good.
We have 5 probes for the 500, all are Nalorac probes and were purchased
within the last two years.
The probes are as follows;
3mm dual broad band, 5mm dual broad band, 5mm indirect det., 5mm H,C,N
indirect triple res. With Z gradient, and a 10mm dual broad band. We will
purchase a 3mm gradient indirect probe in 1997.
Needless to say, I am very happy with the performance of these probes. They
are extremely robust.
As far as technical support, I'm sorry that I cannot make a comparison with
your vendor, however I would not hesitate to rank Nalorac's as outstanding.
Warranty turn around is usually 1-2 days.
If you would like more detailed information with regard to their technical
staff, I know most of them personally and they have extensive background
with respect to NMR in general. Recently, they hired Ron Crouch from
Burroughs Wellcome. Ron has extensive background in NMR and has helped me on
several occasions with other aspects of NMR experiments, (i.e. coding of
some of the more bizarre pulse sequences).
Feel free to
contact me if you need more information,
Regards,
Rick
Wintermute
Dexter
Corporation
East Water
St.
Waukegan,
Il.
847-625-4497
______________________________________________________________________
A very good question. I have purchased NMR probes from four different
'third party' vendors as well as making my own probes (years ago). For
solid-state probes no one can beat Doty probes. I use a Doty probe on my
MSL-300 at all times. In fact I sent one of my old Bruker CPMAS probes to
NIH.
Doty is very good about repairing their probes. I had also purchased a
10mm
solutions probe from them. It was a very nice probe to work with but
unfortunately it was difficult to tune and match.
I have a Varian Unity + 400 sitting in my lab that is two years old.
The spec tests yielded results more typical of a 500 MHz spectrometer (c13
s/n,
10mm probe, 524). In addition I purchased a Nalorac 10 mm probe. The probe
is
beautifully constructed, but I have had a few minor problems, such as
setting
in the upper barrel assembly and spinning. The line shape is decent and the
s/n exceeds Varian spec (450/1) but does not exceed the Varian 10mm probe's
s/n.
Part of the reason that Nalorac has better specs is that the coil is
slightly smaller in diameter and slightly longer giving a better filling
factor. Probe circuitry is fairly simple and it is more an art than a
science
to balance the circuitry for the optimal s/n. All thing considered the s/n
is
dependent more on the rf and magnet. I recently had my magnet mapped and
the
supershims touched up. The result was a nice improvement in proton signal
to
noise.
Personally I would stay with the Bruker probe. It may be a bit
clunky
and the specs not quite as good as Nalorac's, it is more robust and less
likely
to break down. I have not had the opportunity to send the Nalorac probe out
for repairs, but Bruker has been very quick about repairing their probes. I
think this will be the case as long as Brian Andrews is at Bruker. I should
mention that I send a Gemini-200 probe to J.S. Research and I was very
pleased
with the price and the quality of work. The turn around time was one week.
He
may repair Nalorac probes.
Good Luck
Bob Dudley
rdudley@arserrc.gov
______________________________________________________________________
We only have Bruker probes; we have looked a little into Nalorac.
If you ever do direct observe of X, even on an inverse probe, you might
want to have a demo of the sensitivity of your favorite X. In fact, just
in general, a demo of the type of probe that you are interested in may be
a good idea: see how the spectra of the type of compounds that you
work with (preferably stable model compounds :-)look under identical
acquistion conditions for both X and H with quick versions of the
experiments that you use (like NOE diff, COSY, water suppression...).
Real conditions
will tell you more about the probe than height & shape of ethyl benzene :-)
In Nalorac probes, the coil is deposited
on the glassware. If the glass breaks you'll have to send it in
for repair, which might be more $ than Bruker.
(Haven't priced the difference) If the glass gets
dirty, I think you can clean to an extent.
In a Bruker probe, the glass is seperate from the coil,
and breaking the glass usually will not damage the coil. With some
care, you can change the glassware yourself.
This may or may not be a disadvantage of the Nalorac probe,
depending upon your situation.
I have heard that the Nalorac probes are a good alternate choice.
______________________________________________________________________
I have been dealing with Nalorac for a while and can give
you my two cents on their probes. Soon after I arrived at UIC we
upgraded an old WP-200 to a used AC (from M.R.Resources) and dec-
ided to replace the batch of old Bruker selective probes with a
new 5mm BB probe. Nalorac was several thousand dollars cheaper
than Bruker, and their probe specs were just as good. Since I
was familiar with Nalorac from working at Berkeley I decided to
go with the Nalorac Probe. Basically, I've been very happy with
it. It performs very well, especially in terms of lineshape, and
all the S/N measurements easily met or exceeded specs. The only
caveats are that the probe was late being delivered (more later),
and the probe is somewhat hard to tune on the X-nuclei. The
probe uses two replacable capacitors for a fairly narrow freq-
uency band, and tuning for a new nucleus using the Bruker reflec-
tion bridge can sometimes be tedious (i.e. the minimum doesn't
obtain readily), especially for students who don't have experience.
On balance, I've been very happy with it, so much so that last
spring we ordered another probe of the sme type (5mm BB) to replace
the old C/H probe on our AM-400. Again, the Nalorac specs are
very good, as is the price. Unfortunately, our probe was due here
at the end of August and hasn't arrived yet, so it is going to be
at least two weeks behind delivery schedule. I think if I ever buy
another probe from Nalorac I will try to negotiate some kind of
penalty clause for late delivery. I don't know if delivery prob-
lems are common with them, though.
If you have any questions or comments don't hesitate to mail
back.
Regards,
John Harwood
U. Illinois @ Chicago, Chemistry Dept.
harwood@hugh.chem.uic.edu
______________________________________________________________________
have some experience with two Nalorac probes, and can make some comparisons
with Bruker probes. One probe is a 5mm He-3/H-1 probe for our AM-500. It
has very good sensitivity and shims well, and we have had no problems with
it. The other is a 5mm BB/H-1 probe for a GE Omega-300 (reduced bore
magnet).
Performance is good, at least as good as the original GE probe. But we have
had several problems with it. The last problem is loss of lock signal when
the probe is cooled to -40 deg C or so. Sounds like a bad connection which
is
opening up, a bad capacitor so some such thing. The probe has been in the
Nalorac shop for THREE MONTHS for repair of this problem. We have this
probe as
a backup for our GE BB/H-1 probe, so can still get our work done, and have
not been pressing hard for it (like calling daily), but they do know we want
to get it back ASAP. We get a different excuse every time we call about it,
and I am really fed up with dealing with Nalorac. I think they have good
probe designs, and are selling so many probes that all their efforts go into
building new probes and little into service. I haven't bought any new
probes
from Bruker lately, but they do seem to be able to turn repairs around in a
couple of days (though they do screw these up often). Even if you have to
iterate with Bruker a time or two, you end up with your probe back in hand
in working condition in a week or so. Hope these comments are of interest.
Ben Bangerter
______________________________________________________________________
We have a 10mm X-nucleus probe from Nalorac. We don't use it a lot, but it
performs to spec, and on the couple of occasions I've needed to call for
technical assistance, the fellow on the other end of the line has been very
knowledgable, helpful, and has followed through with requested data.
-Pat W.
Patrick Wheeler
NMR Laboratory Manager
Isis Pharmaceuticals
2280 Faraday Ave.
Carlsbad, CA 92008
619-603-3801
pwheeler@isisph.com
______________________________________________________________________
I run the open access labs for 200 chemists. We have 5 Varian NMR's: a
3, two 4's, and two 5's all running Nalarac probes (over 60,000
samples/year. Our oldest probe 5 years(70,000 to 80,000 samples under
it's belt) has been in the shop twice. Turnaround time is 2 -3 weeks. It
still meets spec today. That's why we keep buying them.
Ron Brown
Merck Research Labs, Rahway, NJ
908-594-6659
ron_brown@merck.com
Our Facility has had very good experience with its two Nalorac Probes.
We bought a 200 MHz 5mm proton-only probe about 7 years ago. There were
some
problems in installation, partly our fault, which Nalorac uncomplainingly
fixed.
The initial delivery was then very slow; I understand it is now good.
We bought a 3mm triple probe with gradients for out AMX500...is fine and
performs
well into specs.
Bruker did not offer much resistance when we talked of buying Nalorac probes
instead of theirs for a new purchase (turned out Nalorac could not supply a
gradient probe for out magnet size !?)....so if there were a major
reliability
factor I think they would have been pushing that in my face.
Both probes gave the performances specified and were excellent. We have
since
sold the 200 probe to NC State U and I understand it is still performing
well.
Regards
Charlie
-- ############################################################## Kurt Wollenberg e-mail:kfw@lubrizol.com Research Chemist ph#:(216)943-1200 ext2026 NMR Spectroscopy fax:(216)943-9022 Lubrizol Corporation ##############################################################