Pharma Tips

Inserting Sample on NMR Magnet

By: Pharma Tips | Views: 1018 | Date: 17-Aug-2013

NMR tube containing sample should be held in a plastic spinner (use the blue color spinner in 500 and 600 MHz spectrometers; use the white color spinner in 700 MHz spectrometer). Hold the sample by the top, place sample tube in the spinner and the spinner in the sample depth gauge. Push or pull the sample tube so that the depth of the sample above and below the center line of the sample depth gauge is equal. However, never exceed the lower limit (position of the adjustable white platform which should be at

Inserting Sample on NMR Magnet

Adjusting sample depth with a sample gauge


First, the NMR tube is needed to be inserted into a spinner turbine. For best results, NMR tubes should be positioned in the spinner turbine in such a way that the sample remains centered in the r.f. coil region inside the NMR probe. This can be done with the help of a sample gauge, which usually has a center line and rectangular markings to indicate the probe geometry.

A sample gauge also has an adjustable bottom, which can be adjusted to allow quick positioning of a series of identical samples. Setting a sample tube too low may cause it to break, as well as contaminate and damage the probe!

It is also important to make sure that the tube sits firmly in the spinner. If your sample slides too easily inside a spinner turbine, it may indicate that the rubber o-rings of the spinner need replacement.

Inserting and ejecting

To access the Insert and Eject buttons do the following:

  • VNMR - click on the Acqi button or type acqi
  • VNMRJ - click on the Setup tab

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

Sample change procedure

  1. Eject the current sample first. Even if there is no sample in the magnet you need to use eject to create the upward thrust using the airflow.
  2. Remove the ejected sample.
  3. Place the sample in the spinner in the bore. Verify that you have the airflow to support your sample while still holding the sample. Leave the sample.
  4. Click on Insert to lower your sample.

Avoid leaving the spectrometer with an open bore for long periods of time, as this increases the risk of contamination of the bore with foreign particles. If you need to remove a sample and have nothing else to measure, either insert a standard NMR sample or cover the bore with a dedicated plug.

Inserting Sample 
1. NMR tube containing sample should be held in a plastic spinner
(use the blue color spinner in 500 and 600 MHz spectrometers; use the white color spinner in 700 MHz spectrometer). 
Hold the sample by the top, place sample tube in the spinner and the spinner in the sample depth gauge. Push or pull the sample tube so that the depth of the sample above and below the center line of the sample depth gauge is equal. However, never exceed the lower limit (position of the adjustable white platform which should be at the line marked 5 mm ­  15mm) as this can damage the probe as well as the sample, as the sample will rest on the tip of the tube, not the spinner. This is important for all probes, but especially the cryoprobes installed on the 600 and 700 MHz spectrometers.

2. Remove the black cap from the top of the magnet bore. Next, press the LIFT button in upper left portion of the BSMS keyboard.
 Wait for the airflow (hissing sound that can be heard). Then remove the depth gauge before inserting the sample and spinner into the magnet.
Pressing the LIFT button will toggle the air flow off and will drop the sample tube gently to the magnet bore where it will be positioned at the top of the probe.



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