Shigemi NMR tubes, 5 mm and 3 mm, solvent-matched

What this tube is for

A Shigemi tube lets you record a good spectrum from much less sample than a normal tube needs. It is a set of two parts: an outer tube with a thick glass bottom, and a glass plunger that you lower onto the sample from above. Both pieces of glass are made to match the magnetic susceptibility of one solvent. To the magnet, the sample seems to continue above and below, so the field stays even and shimming works as with a full tube.

The result is that the whole sample sits in the detection region of the probe, at the highest concentration the sample allows. Typical uses: natural products, metabolites, proteins and peptides, and any compound that is expensive or available only in milligram amounts or less.

Your choices

Size: 5 mm or 3 mm. Choose the size that your probe takes. The 5 mm tube fits any standard 5 mm probe and needs roughly half the liquid of a normal 5 mm tube. The 3 mm tube is for the smallest samples: its narrower bore needs even less liquid, but it needs a 3 mm probe, or a spinner that holds 3 mm tubes in a 5 mm probe. If you are not sure, choose 5 mm.

Spectrometer: Bruker or Varian (5 mm only). The 5 mm glass bottom is 8 mm long for Bruker probes and 15 mm for Varian probes. The receiver coil sits higher in a Varian probe than in a Bruker probe, so the Varian tube needs a longer glass bottom to lift the sample to the coil. Varian and Agilent NMR spectrometers take the Varian version. The 3 mm tube comes in one universal version with a 10 mm glass bottom, for Bruker and Varian probes alike, so there is nothing to choose.

Choose the right version: it protects your probe. A 5 mm Varian tube in a Bruker probe pushes its 15 mm glass bottom down into the coil region and can damage the probe. A 5 mm Bruker tube in a Varian probe does no harm, but the sample sits below the coil and the spectrum is poor. If you are not sure which probe you have, ask us before ordering.

Solvent. Choose the tube matched to the solvent you will use: D₂O, CDCl₃, DMSO-d₆, CD₃OD or acetone-d₆. The DMSO-d₆ tube also suits pyridine-d₅ and benzene-d₆, and the CD₃OD tube also suits acetonitrile-d₃, because their susceptibilities are close. A tube used with the wrong solvent gives distorted lineshapes.

The most common choice is CMS-005B: the 5 mm CDCl₃ tube for Bruker instruments.

Technical specifications

Manufacturer