Glass NMR tubes

Transfer fat samples to glass NMR tubes, filling the tubes to a height of 30 to 50 mm. Ensure that no fat adheres to the outside of the tubes. 

Samples were prepared by weighing the components, mixing thoroughly and centrifuging to remove air bubbles. This procedure was repeated in a minimum of two times. Portions of the samples were centrifuged into glass NMR tubes for N.M.R. investigations. 

Small amounts of samples can be analyzed by Raman spectroscopy and a variety of sample holders are available, ranging from stainless steel holders to glass NMR tubes. The samples are analyzed neat, eliminating the need for sample preparation procedures that may induce solid form changes. Since a laser is used, only a small portion of the sample is in the beam during analysis. 

Apart from an NMR spectrometer there is also a need for a tritium probe before one can obtain a NMR spectrum. For safety reasons, it is best to insert the radioactive solution in a narrow cylindrical tube which is then sealed at the top prior to being inserted in a conventional glass NMR tube. This double containment procedure has now been in operation for many years without any recorded breakages. 

In the middle of the NMR probe is the sample compartment. Mostly cylindrical, it is made to accommodate a long glass NMR tube which contains the sample. 

---