Bruker 700

On March 26 there was a brief power outage and the power the shared 700 wasn't restored before the UPS quit. There was a fuse in the third floor panel room had tripped and that impacted the power for just this unit and the 800 magnet pump. After resetting the fuse power was restored and the cryoprobe warm-up was completed. The turbo pump was kept running overnight to achieve cold box vacuum and on March 27 cool-down is underway.

We started (10/8/2013) the shim stability test using autotest sample that has 1% water, methanol, and acetonitrile in D2O. We started the experiment at 5:30PM and ran it for 12 hours. At the start, we had just closed the big outside door to the lab and the room temperature was, perhaps, still stabilizing. The 12 hour run results show a slow predominant Z1 shim change which was also pronounced in the earlier part of the evening. The line shape remained intact throughout except for the broadening effect. Up on correcting Z1 shim by about -90 units the shim level and lock level comes back.

The shared 700 NMR is up and running with RT probe.

As per Seho's mail:

"

Data run during the weekend were stored under /data/Skim/Jerry101513;
20 trosyf3gpphsi19.2
21 trhncacbgp2h3d.x
22 trhncagp2h3d.x

We set up again another stability test (10/9/2013) with Z1 auto shim and the results are encouraging. The lineshape and intensities were very stable that too in the initial part where we saw degradation before without Z1 shim. The lock level also remained steady.

Next course of action: In order to isolate if it is really Z1 shim or magnet pressure instability, we will install the manostat and repeat the stability test. This might help us narrow down the issue further.

A manostat was added to the 700B magnet on 10/14/2013. It did not alter the lock level drop and Z1 drift behavior. Opened a ticket (#150200) with Bruker on 10/16/2013. They analyzed the stability data and looked at stability data with just supercon shim and supercon shim + RT Z1 shim alone. Bruker's final conclusion is that the supercon Z1 needs touching. Currently, awaiting Bruker's recommendation for the course of action.

The Bruker 700 cryoprobe service started on Monday May 16, 2016 and completed on Tuesday, May 17, 2016 afternoon.

The annual cryoprpobe maintenance was started on May 18,2015.

The 700B outside compressor for the cryoprobe was swapped by Bruker.

The cryoprpbe was cooled down on Friday May 22, 2015. This time the cooldown/service took longer than usual as a filter pack had burst in the He supply line. The Cryobay was cleaned and the filterpack was removed from the supply line and reccoled. The coil heater is at 30% and preamp heater at 170%. The pulse widths have shortened by about 5% after service.

Paolo brought to our attention an issue of cold probe shimming using topshim with our shared 700 (Bio NMR lab). The sample is protein in 90% H2O about 300ul in Bruker Shigemi tube. When we center the shigemi tube with the depth gauge coil center marking topshim B0 standard deviation after shimming is anywhere between 5 to 10 Hz. Seho and I could reproduce this observation.

Bruker's Clemens Anklin evaluated the topshim data and gave the following response.

"the profiles look fundamentally ok but some are shifted.

Sucrose looks perfect.

The annual cryo probe service was completed on Friday June20, 2014. The system is working fine.

Bruker has been contacted to do cryo platform service. They are in the process of scheduling the service and checking cryo probe performance.

From Seho:

Bruker recommends to replace the He compressor since the current service could not make the cryoprobe working normally. They think that the outdoor He compressor could not build up the right pressure. They will send another quote costing about $25,000.

In the meanwhile they are working here, they will diagnose the problem related to the RT probe.

There is a clear correlation between increased NMR bore temperature and a concomitant decrease in NMR coil heater power. The bore temperature seem to increase when higher sample temperature is set say above 25C. The preamp heater power is quite stable.

bore temperature/NMR coil heater/preamp power
301.86/17%/146% sample temp 25C
304.89/15%/145% sample temp 28C
305.04/16%/148% unknown sample temp (must be close to 28 C)
309.13/14%/147% sample temp 32C
327.34/7%/146% unknown sample temp

The temperature gas flow is 670 L/h.

The cryoprpbe coil heater power is dropping. After the re-installation 7/19/2013 the coil heater power was 21% and then it dropped to 19% on 7/22/2013 and on 7/23 it is at 7%. Bruker has been contacted.

Bruker response is that the readings are nothing to be alarmed and so we will wait and see.

RT probe is back from Bruker. We are checking with Bruker about cryo platform service schedule to decide whether to install the RT probe at this time.

The RT probe is with Bruker to check tuning issues with salty samples.

Yesterday (6/25/2013)– the Bruker guys did not have time to do the testing. They did it this afternoon. They tested the probe with Babis 700 console outside the magnet and there was no problem. We tested the probe outside the magnet with the shared 700 console again to eliminate any magnetic material in the proton coil that might have disturbed the tuning while the probe was inside the magnet and the tuning did not work. So the source of trouble seem to be with the console.

Message from Seho Kim: The repaired RT probe looks OK to tune the 1H of salty samples. I will shim and check specs further. The 700B may be available tomorrow morning. Since the 700B topspin was upgraded to 3.2, please use the right version.

Bruker 700 NMR (by Seho Kim)
Two minor issues (marked with * and **) will be checked again.
Drift; 0.89 Hz/hr
Stability (>98%); > 99%
Lineshape( 1*/8/16); 1.4*/7.0 /14.8; The original spec shows no value for linewidth at 50% (*)
Sensitivity (1150, sucrose); 946**; This is no change since the last year.
1H pw90; 7.8 at -12.04
13C pw90; 12.3 at -22.36
15N pw90; 26.5 at -22.89
2H pw90; 93 at -15.0
hsqcetfpf3gpsi; OK
hsqcetgp; OK

Bruker engineer is working on the 700B cryoprobe system. The helium compressor was replaced in this morning and testing the cryoprobe will be followed sometime. 700B will be down until announcing the availability.

Seho Kim

The Bruker service was done for replacing the He compressor and the 1H pw90 of the cryoprobe was tested quickly. The 1H pw90 was 8.24us, which is the same as the value we have when the cryoprobe runs normally. It looks replacing the He compressor fixed the problem. Tomorrow, I will continue some tests further and tomorrow afternoon 700B will be open to users.

Seho Kim

700B with the cryoprobe looks OK to use.
Filling helium will be scheduled on 7/25(Thu) for 600V (9am-11am), 600B (10-12), and 700B(1pm – 4pm).

Seho

Bruker thinks that the Proton preamp at the shared 700 is not working properly. Replacing that might solve the RT probe proton tuning issues. Awaiting a quote for the preamp.

The 1H preamp and filters came in yesterday and these were installed. 700B will be ready to use today afternoon after checking pw, installing trosy relaxation experiments, and filling LN2. While Bruker engineers were checking the 700B2 cryoprobe, they helped to install the preamp and found that the tuning display by ATMM was not shown correctly when sw was reduced comparing to the default sw=15MHz. They think that it might be related to the software upgrade for the old HTTP/2 but tuning function and display are OK with default sw.