Proton ‘Spin Saturation Transfer’ experiment (PROTONSST)
with TOPSPIN
Available on b500b and b400b.
(A) Run PROTONT1 experiment to get T1 value
(see separate sheet).
(Or follow t1ir_guess_note to get rough T1 value).
(B) Acquire Normal proton spectrum and get ‘rg’(Receiver Gain), ‘O2p’.
(1) Create Normal Data file
(Click) “File” -> (Click) “New” ->
“NAME” filename
“EXPND” 10
“PROCNO” 1
(2) Run normal proton experiment
(Type) ‘rpar PROTONSST all’ -> (Type) ‘getprosol’ -> (Type) ‘ns’ and (enter) ‘8’.
(type) ‘d1’ and set d1 > 5 T1. Set O2: (Type) ‘o2p’, enter -2 (ppm).
(3) Lock and Shim as usual
Load shim file: (Type) ‘rsh’ -> (select) “xxx_current.shim”.
Select solvent and lock: (Type) ‘lock’ -> (select) “CDCL3”.
After lock is on, (type) ‘gradshimau’.
(4) Get normal proton spectrum
Set gain: (Type)’rga’.
Acquire and display FID: ‘zg’-> ‘lb’ ‘efp’ ( bc + em + ft
+ pk) and phase it.
Write down rg’s value, and estimate ‘ns’ for PROTONSST experiment.
(5) Set O2 value for saturation.
Use “Set RF from cursor” to set the O2p value of the peak (B), which will be saturated.
(6) Get the signal intensity of the peak(A) monitored and write it down as M0.
(C) Acquire PROTONSST data
(1) Create Data file
(Click) “File” -> (Click) “Copy” “Acquisition parameters” to “EXPND” 20 ->
(Click) “File” -> “New” -> select EXP 20:
“NAME” filename
“EXPND” 20
“PROCNO” 1
(2) Select PROTONSST experiment parameters:
(Type) ‘O2p’ and check the value.
(3)Acquire and display FID: ‘zg’-> ‘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.
(D) Selectivity.
with pl14=60, d1=30, the selectivity can be 64 Hz.