Inserting NMR Sample

Sample Loading

Using the sample gauge

The optimal volume for NMR samples is 500-600 uL for 5 mm regular NMR tubes and ~300 uL for Shigemi tubes. Before the tube is put into the magnet, the optimal position of the tube in the sample holder should be measured in the gauge as shown in the figure below. For best results the sample should be centered relative to the dashed rectangular area of the gauge.

IMPORTANT! The bottom of the sample should never be lower than the bottom of the gauge! Failure to observe this may lead to sample breakage and damage to the probe!

Also important is use good sample holders whose o-rings are not worn out. If your sample slides too easily when inside a holder try another one.

Figure1. Positions of NMR tube in the gauge. Left, regular tube; right, shigemi tube.

Insert and Eject

In VNMR:

1. Click on the Acqi button or type acqi
2. Use the Insert and Eject buttons in the Acqi window

In VNMRJ:

1. Click on the Setup tab
2. Uset the Insert sample and Eject sample buttons in the middle of the screen

You can also type insert or i and eject or e at the VNMR or VNMRJ prompt.

Procedure

1. Eject the current sample first. Even if there is no sample in the magnet you need to use eject to create the airflow.
2. Remove the ejected sample.
3. Verify that you have the airflow to support your sample. Carefully insert the sample in the bore.
4. Select insert to lower your sample

Figure2. Acquisition window.

Do not leave the spectrometer with an open bore for long periods of time. If you have to remove a sample and have nothing else to measure, either insert a standard NMR sample or cover the bore with a dedicated plug.

-- Main.GaohuaLiu - 24 Jan 2007