Variation in the wall thickness of an NMR tube (causing poor concentricity) can cause the magnetic field to be distorted in the sample region because the magnetic susceptibility of glass is usually different from that of the sample liquid.
Accordingly, through our advanced manufacturing process, round NMR tube bottoms are uniformly hemispherical, while the flat NMR tube bottoms are precisely planar with minimal curvature at the transition to the bottom. Both styles of bottom finish are manufactured with a thin, consistent wall thickness throughout, thereby minimizing shimming and susceptibility differences among samples that can be caused by large, spherical or irregular masses of glass forming the bottom, as can be seen in some competitor's NMR tubes.
This uniformity extends throughout the wall thickness of the tubes, maximizing the concentricity among tubes and lots. This translates to more consistent placement of the contained sample volumes in today's advanced, highly homogeneous, high field NMR magnets, shortening the shimming time required, and thereby increasing sample throughput by reducing analysis time.
A superior degree of concentricity in NORELL® NMR tubes and bottoms yields higher resolution spectra with sharper peaks showing better definition and symmetry, especially when spinning samples.
Improved resolution allows improved measurement of j-coupling constants, and an increase in signal to noise for greater data reliability when operating close to the spectrometer's noise level.
NMR tubes are manufactured with round bottoms and are available with flat bottoms upon request. We manufacture all NMR tubes in any length upon request.