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Ensure Reliable NMR Sample Spinning with Dry and Clean Air

Sample spinning is a must for any NMR instrument to perform optimally, so an air supply must be in place in order to meet this need.  We can configure our instruments to use either a local air supply or house air, but we must first explain to users the effects of air quality on spinning before determining the proper air supply.

Air Quality Effects on Probes and Spinners

In the interest of instrument longevity and reliable spin capabilities, air should be clean and dry. This is because moist, dirty air causes oxidation to occur on the stator (below, right).  The stator is the part at the bottom of the probe where samples spin.  This spin-impeding oxidation occurs faster in moist environments than in dry ones and builds up over time.  The sample spinner directly contacts the oxidation on the stator and collects dirt over time, so we recommend occasional spinner cleaning with isopropanol to keep friction down.  Users can also follow the steps found in this blog as needed to remove oxidation and dirt from the stator for consistent spinning.

Left:  top view of EFT-90 Probe.  Right:  zoomed in photo of the stator, where spinning takes place.  This surface is susceptible to oxidation over time.

Dirt buildup and stator surface oxidation are inevitable, even in a clean, dry air environment.  However, with proper spinner handling and cleaning, users with high-quality air will see long intervals between stator cleanings.  Moist, dirty air will always require more probe and spinner upkeep than will clean, dry air, which is why air quality is of utmost importance.

Benefits of High-quality House Air

House air is ideal for our systems.  Here are a few perks that house air brings:

  • Easy-to-handle air pressure requirements (10-15 PSI)
  • Consistent, reliable airflow, perfect for users who run experiments with many scans
  • Convenient sample control using only two valves mounted right onto the magnet
  • Avoidance of added noise from a local air pump

Further Considerations

Users whose house air systems fail to provide clean, dry air may want to consider an independent, local air supply for improved air quality and longer intervals between probe cleanings.  Here is a breakdown of the similarities and differences between the two air supplies that Anasazi offers. 

Please contact us at 866-494-9369 with further questions.