TECHNIQUES

Proton

One of the most basic of all NMR experiments allows an initial view into the nature of the molecule being investigated, the spectrum can be simple to interperate or can be very complex, especially for large molecules. The proton spectrum is the most basic and least time consuming experiment typically, taking minutes to run but some times hours or days to interpret.

Carbon

The Carbon spectrum is another of the "simple" and basic spectrum for NMR, a wealth of information which helps unravel the structure of compounds examined by this technique, the typical carbon spectrum takes many hours to run, the natural abundance of 13C is 1.1% of its natural counterpart carbon 12. Labelled 13 C experiments can take minutes dependant on the percentage enrichment of the isotope in the sample.

DEPT

Distortionless enhancement by polarization transfer is a heteronuclear experiment (normally 13C -1H), the experiment determines whether a resonance signal found in the carbon spectrum is from CH3 , CH2 , CH or a quaternary carbon. The most common results from this experiment are readily interperated as the CH3 and CH peaks are of normal phase and the CH2 peaks are of opposite phase (inverted) this is called a DEPT 135, On the GEMINI the software routine in the DEPTP Macro plots and labels the spectra in to three experiments.

APT

The Attached Proton Test is a simple experiment which helps in elucidation of structure by determining what type of Protons are attached to Carbons, the spectrum takes as long as a carbon analysis to run but does not show and quartinary/carbonyl carbons in the resultant spectum.

COSY

This is a 2D (2 dimensional) homonuclear experiment, normally 1H. COSY is basically like doing a whole series of the homonuclear decoupling experiments (1D) in a fully automated mode, the results are in a 2D array which shows the spin-spin coupling between all nuclei in the sample to be presented on one single page.

HETCOR

The HETCOR experiment is a hetronuclear 2D (2 dimensional) experiment typically usefully for 1H - 13C correlation. The experiment has a 1H component and a 13C component the data plotted has the 1H on one axis and the 13C on the other, the so called Carbon - Proton correlation can be assigned making structural elucidation a much easier task.

Queued Experiments

The Gemini allows experiment queuing, that is a series of experiments can be set to run automatically without the operator present, there are a number of experimental areas that are available for the operator to setup for a particular experiment. Eg:

Experiment 1 may be setup for a Proton experiment

Experiment 2 for a Carbon experiment

Experiment 4 for a COSY experiment

Experiment 5 for a DEPT experiment

These are simply started in any sequence and the software will automatically queue the experiment that are started after the first acquisition is started. The data will be saved in that experiment and can be processed at a later time. This is an excellent way of doing a number of experiments over night or a weekend.