Clean NMR Tubes [The best & effective ways]
Although the NMR Tubes that we supply from Norell who are a renowned name for NMR Tubes are purely clean. But with regular use comes regular cleaning of the NMR Tubes.
To remove the residues of the sample whether inorganic or organic the cleaning procedures explained will help in keeping the purity of samples safe without causing any hassle to your NMR tube. Cleaning the NMR Tube the incorrect way causes damage and further the performance.
A brush should never be used for cleaning the NMR Tube as it can cause scratches and easily distort the perfect cylindrical shape of the NMR Tube. Another disadvantage of having scratches inside can result in a different magnetic field inside the NMR Tube and that will result in distorted output.
Rest of the blog post explores cleaning of NMR Tube with 3 cases,
- Easy Cleaning of NMR Tubes
- Removal of Water from NMR Tubes
- Difficult Cleaning issues of NMR Tubes
Easy Cleaning of NMR Tubes
Use water or an organic solvent but only one at a time to clean your NMR Tubes. A proper rinse with Acetone is recommended to remove the last of organic contents in the tube.
Removal of Water from NMR Tubes
Never use high temperatures for drying the NMR Tube as it can ruin the overall shape. Ideal temperature is 125° C kept on a flat tray for 30 minutes. Yet at ideal temperatures there are traces of water observed inside the tube which is usually absorbed the surface of the tube. The reasons for this is the protic content of water and to exchange the protons of chemisorbed water with a deuterated solvent such as D2O prior to drying period in the oven.
Make sure that water is properly removed from the NMR Tube as it can chemically degrade the samples.
Difficult Cleaning issues of NMR Tubes
Difficulty arise when samples are kept inside the tube for longer periods. In such cases ideally use Nitric Acid. For severe cases the Nitric Acid can be soaked for a period of 1-3 days. Nitric Acid oxidizes many organic chemicals and dissolves most inorganic materials.
For polymeric samples cleaning process is more difficult. For the natural polymers, like proteins and polysaccharides, strong acid soaks will usually be sufficient. But with synthetic polymers, the challenge is more severe, since many polymers are inert to acids or insoluble in organic solvents by design. If polymers are not getting dissolved in solvents, then ideally soften them by soaking the tubes in a solvent that swells the polymer. Then a pipe cleaner might be sufficient to remove the softened material. It would take some experimentation to find the solvent combination that works best.