Product/Service

Doty Susceptibility Plugs

Doty Susceptibility Plugs are provided as a set of two. Positioning Rod and Collar are provided as a set and are ordered separately from the plug set. The upper face of both plugs has a thread that lets you firmly attach a positioning rod
  • Easier to use than the glass alternative
  • Can be used with a wide range of solvents
  • Use them with existing tubes
  • Lower in cost than glass
  • Less fragile than susceptibility-altered glass microtubes

Traditionally, sample sizes were 3-5 times the height of the probe Rfcoil. All magnetic field distortions caused by magnetic susceptibility discontinuities at the upper air-sample and lower glass-sample interfaces were far from the sensitive probe Rfcoil region.

Small samples diluted to larger traditional volumes (1mL) yeild poor NMR spectra in high field spectrometers.

Through magnetic susceptibility matching of the sample solvent, Doty Susceptibility Plugs allow the sample to be substantially concentrated by extending out the air-sample / glass-sample interfaces far enough away from the Rfcoil region to remove the magnetic field distortions.

Doty Susceptibility Plugs are provided as a set of two. Positioning Rod and Collar are provided as a set and are ordered separately from the plug set. The upper face of both plugs has a thread that lets you firmly attach a positioning rod. The upper plug is held in place by the positioning rod. The rod, in turn, is held in place by a collar that rests on the top of the tube. A special sealing collar (equipped with two o-rings) can be ordered separately for long term storage of samples where solvent evaporation can alter results. The sealing collar is used to replace the standard positioning collar on the rod.

Advantages of Doty Susceptibility Plugs

  • Designed for use in WILMAD "thin walled" NMR sample tubes (7 and 8 inch length)
  • Eliminate glass tube breakage
  • Designed for easier air bubble removal. Product numbers witha "V" have vent grooves along the outer surface for easier bubble removal and for use with viscous samples/solvents
  • May be removed from the sample tube with minimal sample loss (1-2%) aftra spectra are obtained and them used with other samples

Steps to Consider when Selecting Susceptibility Plugs

  • Determine the sample solvent.Note: for easier bubble removal and for use with viscous samples/solvents, plugs with vent grooves along the outer surface (product number with a "V") should be used.
  • Select plug material-closest match of magnetic susceptibility constants.Note: density of plugs must be greater than density of sample-solvent.
  • Check chemical resistance compatibility with sample/solvent.
  • Make sure unwanted background effects of nuclei in plug material do not interfere with the analysis.
  • Check water absorption factor.
  • Determine plug length which depends on Rfcoil position, sample height and distance from coil bottom to probe head bottom.

Susceptibility constants of rod/collar are inconsequential. Rod/collar material selection is based on chemical resistance. G-10 rods are more rigid and easier to use; Kel-F rods are recommended for use with organic solvents.