Tweaks have been made to all default 1H and 13C 1D and 2D experiment parameter sets so they have been tested as effective and are the same on all spectrometers. If you have a 10mg properly-prepared sample, you are assured of getting good data using default parameters with these experiments no matter which instrument you use.
Experiments / Parameter Sets
The following have been updated. The names on the 500s are preceded by numbers not shown here; these numbers provide a means of ordering the lists so the most commonly used experiments “rise” to the top.
*1D 13C spectrum with “inverse-gated” decoupling, in which 1H is decoupled during acquisition but is not on during the D1 delay. “Normal” carbon spectra are acquired with 1H irradiation during the D1 delay to build up 13C signal strength via the heteronuclear NOE, but the extent of enhancement varies greatly among different carbon signals, making it unsuitable for meaningful integration.
COSY / COSY-opt
HSQC / HSQC-opt
HMBC / HMBC-opt
HSQC-TOCSY / HSQC-TOCSY-opt
(The “-opt” experiments are the versions on the 400’s that optimize 1H spectral with automatically. This must be done manually on the manually-operated instruments, but the “Set Limits” tool in the Acquire tab helps with this.)
The approximate experiment time, within 15 sec, is now listed at the beginning of each experiment’s “title” file, helping you gauge the length of each experiment.
If you have less then 10 mg / mL sample, you should consider increasing the value for the parameter NS, the number of scans. The best value for NS given a particular sample concentration depends on the type of experiment and the configuration of the spectrometer – a topic that will be addressed in another blog post.
|time||20 sec||36 sec||10 min||6 min||3.5 hours||18 min||2 min|
*AQ for PARAMAG-1H differs on 400 and 500 MHz systems due to limitations of receiver hardware.
**Optimization of 1H D1, AQ, and excitation angle was covered in this blog post:
***Optimization of 13C D1, AQ, and excitation angle was covered in this blog post:
||16 min||10 min|
|NS||1||“1” (really 2)||2||2|
*Experiment time depends on SW in F2 (the directly-detected dimension), and to a smaller extent, on SW in F1 (the indirectly-detected dimension). Narrowing SW(F2) for an HSQC, for example, from 16.0 ppm to 7.0 ppm results in a new experiment length of 10.5 minutes. The same adjustment for a COSY experiment lengthens the experiment from 6.5 min to 7.75 min. THe relationship between SW, AQ, and experiment time will be covered in a future blog post.
**The TOCSY portion of the HSQC-TOCSY has a mixing time, which is specified with the “delay” parameter D9, and is given in seconds. A 60 msec mixing time is therefore specified as 0.060.