> Get Spectra From as Little as 1 Microgram of Sample

Microcoils provide greater sensitivity than conventional NMR detector coils to receiving the NMR magnetization signal from small amounts of sample.  This is explained by considering that the process of signal induction in the windings of the detection coil is more efficient when the windings tightly couple to the sample.  Microcoils employ a solenoidal geometry, which is a tightly-wound, multi-turn structure in which the RF (B1) field is highly focused in the interior region of interest (the region where the NMR flowcell is positioned in the CapNMR probe.)  In contrast, the RF coils employed in conventional tube-based probes are typically of the saddle coil (or Helmholtz) variety.  Saddle coils are essentially a loosely wound, 2-turn solenoid, shaped to accommodate the passage of an NMR tube between the two turns of the coil.  This compromise in design is made to facilitate sample change, where tube insertion and replacement is required.  The B1 field must remain perpendicular to the main (B0) magnet field, and a multi-turn solenoid would not permit tubes to be loaded from the top of the magnet into the coil.  The loosely coupled saddle coil design results in a sensitivity loss of approximately 2-3-fold compared to a solenoid of comparable size (Hoult and Richards, J. Mag Res. 24, 71, 1976).  Smaller solenoids are more mass-sensitive than larger solenoids, resulting in an additional scaling factor that is approximately proportional to coil diameter.  The result is that a 1mm-scale solenoidal microcoil is approximately 10-fold more mass-sensitive than a conventional-scale saddle coil.  Microcoils enable you to use less sample, while providing the same spectral information obtained using a larger coil.  This means that you can save time and money by using less and from the ability to get the same information from micrograms (or less) of sample.

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