P31 ‘Spin Saturation Transfer’ experiment (P31SST) with TOPSPIN
It is available only on b400b. For Proton, enter ‘rpar PROTONSST all’ instead.
(A) Follow t1ir_P31_note to get T1 value first.
(B) Acquire Normal P31 spectrum and get ‘rg’(Receiver Gain), ‘O1’.
(1) Create Normal Data file
(Click) “File” -> (Click) “New” ->
“NAME” filename
“EXPND” 10
“PROCNO” 1
(2) Select normal P31 experiment
(Type) ‘rpar P31SST all’ -> (Type) ‘getprosol’ -> (Type) ‘ns’ and (enter) ‘8’.
(type) ‘d1’ and set d1 > 5 T1.
(3) Lock and Shim as usual
Load shim file: (Type) ‘rsh’ -> (select) “qnp_current.shim”.
Select solvent and lock: (Type) ‘lock’ -> (select) “CDCL3”.
Manual shim z1, z2.
(4) Get normal P31 spectrum
Set gain: (Type)’rga’.
Acquire and display FID: ‘zg’-> ‘acqu’ -> ‘tr’ -> ‘lb’ ‘efp’ ( bc + em + ft
+ pk) -> (select)”phase” -> (select)”biggest” -> (select)”PHO” and “PH1”.
Write down rg’s value, and estimate ‘ns’ for P31SST experiment.
Look at te spectrum to make sure that no P31 peak was suppressed.
If there is a peak was suppressed, change o1 to avoid it (see below).
(5) Set O1 value
Set ‘O1’ on the peak (B), which you would like to irradiate.
(6) Get the signal intensity of the peak(A) monitored and write it down
as M0.
(C) Acquire P31SST data
(1) Create Data file
“File” -> “copy” “Acquisition parameters” to “EXPND” 20 ->
“File” -> “open”
“NAME” filename
“EXPND” 20
“PROCNO” 1
(2) Select correct parameters:
(type) ‘O1’ and enter the value obtained before. Check ‘rg’.
(3)Acquire and display FID: ‘zg’-> ‘acqu’ -> ‘tr’ -> ‘lb’ -> ‘efp’ ->
-> Get the signal intensity of the peak(A) monitored as M.
(4) Increase ‘d1’ until the intensity of the peak(A) not reduced anymore,
and update its value.
(5) Calculation
Your rate constant for process A -> B is
k = (1/Ta)(M0/M - 1)
Ref.: Journal of Chemical Education, Vol 74, No. 8 August 1997.