Donna Baldisseri Boston Massachusetts Pre-ENC Workshops 2014, March 22

Deuterium – more than just for locking: Part II 2H Topshim

Topshim

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• Fully automated • Reliable • Easy to use • Customizable • Good, rapid results

M. Weiger, T. Speck, M. Fey Gradient shimming with spectrum optimisation JMR 182, 38-48 (2006)

Using Topshim

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1. Open data set 2. Lock for correct solvent with *lock Topshim automatically selects the desired shim

method depending on the solvent 3. Start shimming

*Lock parameters have been optimized, especially lock phase.

Using Topshim – spectrum optimization

M. Weiger, T. Speck, M. Fey Gradient shimming with spectrum optimisation JMR 182, 38-48 (2006)

2H Topshim

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Advanced 2H Topshim

• Useful parameters • Customizing a new solvent

• Convection Compensation

• Topshim Tips

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Useful Parameters

Additional parameters: not checked checked

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Useful Parameters

Command line arguments can be added here when the box is checked

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Useful Parameters

• ordmax= sets the maximum total order of shim functions (default = 5) ordmax=3 limits shimming to Z-Z3 (1mm and 1.7mm probes) topshim ordmax=8 (SmartProbe)

• 1H or 2H explicitly sets shimming nucleus

• lockoff enables shimming with system unlocked • o1p= explicitly sets excitation frequency in PPM topshim 1H lockoff o1p=2.49 (DMSO-h6)

• selwid= enables selective excitation of a bandwidth expressed in

PPM Useful when shimming on a solvent with multiple signals topshim o1p=1.93 selwid=0.5 (CD3CN+D2O) • zrange sets the range in CM in the Z direction used for shimming topshim zrange=-0.8,0.8 (short sample)

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Useful Parameters

• durmax= maximum duration per 1D field map acquisition

• rga force receiver gain optimization before shimming topshim ordmax=8 rga durmax=60 (CDCl3 in SmartProbe)

• tune* also shim on the lock before or after gradient shimming

(tuneb shims X,Y,Z,XZ,YZ before running gradient shimming) topshim tuneaz (shims Z after running gradient shimming)

• shigemi used to eliminate unreliable data at axial Shigemi tube walls

when 1D shimming

• calreset reset all calibration results for the current probe

• cal force the execution of all calibration procedures for the current probe; a water sample must be used

• plot saves data after completion in <TopSpin_home>/data/topshimData … read about more in the Topshim manual!

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Advanced 2H Topshim

• Useful parameters • Customizing a new solvent

• Convection Compensation

• Topshim Tips

2H Topshim – adding a new solvent

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New Solvent – 2H Shimming

Mixed Solvent - (mixture of CD3CN and D2O)

edsolv

edlock

New Solvent – 2H Shimming

New Solvent – 2H Shimming

New Solvent – 2H Shimming

CH3CN+D2O rg=2.8

CD3CN+D2O rg=16

*

*

+WET

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Advanced 2H Topshim

• Useful parameters • Customizing a new solvent

• Convection Compensation

• Topshim Tips

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2H Topshim – convection compensation

• Convection from temperature gradients • Raising temperature + filling height too high = problems

2H Topshim – convection compensation

•Sample temperature After changing the sample you need to wait for a sufficiently long time (e.g. 60 to 120 sec) to allow the sample to reach a stable temperature, depending on the difference of the room and the sample target temperature. Otherwise a shim setting optimal at the initial temperature may not be appropriate at a later stage. Furthermore, operating close to the boiling point of a sample should be avoided as this may cause serious signal loss during the shimming acquisition due to convection. The latter problem can also be associated with temperature gradients in the probe. Finally, you should always make sure that the gas flow is set correctly as specified for your probe. Topshim manual, pg. 21

2H Topshim – convection compensation

• In order to eliminate / reduce convection:

– Sample filling height =< 40 mm – Increase VT gas flow (if possible) – Spin sample (if possible) – Lower sample temperature (if possible) – Use solvent with higher viscosity (if possible) – Use Shigemi or smaller sample diameter

2H Topshim – convection compensation

The convcomp parameter sets a flag for Topshim to use convection compensation. imgegpcv1d, imgegpcvsp1d2h (gradshim pulse programs) (Topspin versions > TS2.1PL5)

2H Topshim – convection compensation

G

α d15

d27

Z

B0,ω0

-520 15 10 5 0 ppm

-520 15 10 5 0 ppm

TE 2

TE 2

d15 2

d15 2

-520 15 10 5 0 ppm

d27

1H

G

α

2H Topshim – convection compensation

Convection scenario: • lineshape sample (0.3% CHCl3 in Acetone-d6)

• 62 mm filling height (40mm for 5mm probe)

• R.T. → 40°C (ca. 10sec) (>60sec)

• 400 l/hr (CryoProbe) (670 l/hr for 5mm CP)

with convcomp no convcomp

2H Topshim – convection compensation

4.7.2 10 mm probes Samples with a large diameter are prone to convection in the sample which may hamper the gradient shimming procedure. Therefore, it is advantageous to perform 3D shimming on a sample which has a higher viscosity than H2O. A very good candidate is the Bruker standard sample ASTM constisting of 40% p-dioxane in 60% C6D6. With this sample field mapping is performed on the 1H peak at 3.475 ppm which is achieved with the following command: topshim 3d 1h o1p=3.475 Alternatively, the already provided parameter file can be used topshim 3d astm See also 4.5.2 for a detailed description of the parameters.

Topshim manual in Topspin, pg. 38:

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Advanced 2H Topshim

• Useful parameters • Customizing a new solvent

• Convection Compensation

• Topshim Tips

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Topshim Tips

• Check 2H pulse length • Poor initial B0 homogeneity

• Shims can be too bad for Topshim to get data good enough to use for the calculation.

• Try running topshim with sample spinning. • Try topshim tuneb to improve initial homogeneity.

• S/N too low

• Try running topshim durmax=30, 60, or even 120

• Examine Topshim data • topshim plot

Topshim Tips

• Fid #1 is acquired with a longer echo time than fid #2.

• Using multiple display, profiles should have similar intensity. If long echo time spectrum is <0.5 then there may be homogeneity issues, which can be addressed with:

topshim tuneb topshim 3d For 2H, check pulse length.

fmc

Topshim Tips

• Errors and possible causes:

• “no signal at all” or “no signal in centre” • Incorrect routing or RF cable not connected • Protonated or incorrect lock solvent

• “signal-to-noise is too low” • Incorrect 2H pulse • Insufficient lock solvent

• “the (Z) gradient does not work” • Gradient cable not connected or gradient amplifier off

• “too many points lost during fit”

• Starting shims are too bad • Convection

And finally: *topshim plot (<Topspin_home)/data/topshimData) *topshim log (<Topspin_home>/prog/curdir/<user>) *Just send it to us (center@bruker.com)!

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