Wait…..where’s the solvent peak?

Experienced superconducting solenoid NMR users – you know the drill:

Step 1: Make up NMR sample.

Step 2: Look at available NMR time & book a slot (which, of course, can be step 1, you know, depending on the accessibility of NMR time at your facility).

Step 3: Lock, shim, run NMR

Step 4: Reference to the residual solvent peak.

Step 5: Baseline, phase, peak pick, integrate etc. i.e., process as necessary….

 

 

For pros already seasoned to the above routine, there are some obvious differences when acquiring data with the NMReady:

Step 1: Make up NMR sample (standard procedure – albeit more concentrated then you may be used to).

Step 2: Walk to the NMReady…..you don’t need to book NMR time…..the spectrometer’s in your lab!

Step 3: Check what solvent is selected – if it is the same as your sample, you do not need to shim – the machine is good to go!  If not, select the correct solvent and the NMReady will automatically lock and shim on a reference sample.  Once this is done – run NMR.

 

Step 4: Wait? What?  Where’s the singlet at 7.24 ppm? No residual solvent peak?!?!?!?!

Do not be alarmed.  There are two reasons for this:

1) We recommend concentrations in the ≥0.2 M range.  This is much more concentrated than you’re used to, so the solvent peak will be inherently less intense.
2) Given the lower sensitivity of a 60 MHz spectrometer relative to a higher field instrument, this is primarily lost in the baseline.

Oh, okay then…..but how do I reference?

In short – there is really no need to reference the sample.   The NMReady re-locks upon each scan.  This means that the drift is negligible and the observed resonances are automatically corrected to the solvent you’re acquiring data in.  If this is not sufficiently adequate for your application, the addition of 4 drops of trimethylsilylchloride (Me3SiCl, TMSCl, δ = 0.00 ppm) will provide you with assurance that your resonances are at the correct chemical shift.

Step 5: Baseline, phase, peak pick, integrate etc. i.e., process as necessary….