Page 4 of NMR Sampling Tubes, Supplies & Accessories by Wilmad Labglass

iso 9001:2000 registered certificate 77689 1/5/2001 technical support please call our technical support group for any questions where an experienced staff member will assist you with your order 1-800-220-5171 ext.626 or email spectroscopy@wilmad-labglass.com international callers dial 856-697-3000 ext.626 email international@spindustries.com or contact your local authorized wilmad/labglass distributor explan at ionofconcentricityandcambermeasurementsanditsimpo rta nceforthenmrspectroscopist concentricity is defined as a measure of the lack of uniformity of the wall-thickness of the tube this tolerance can be thought of as the degree to which the cylinders as defined by the inner and outer surfaces of the tube parallel and overlap determined using an indicating gauge this tolerance is reported as a deviation ± or total indicator reading t.i.r i.e the absolute variation in wall thickness at the ends of a tube being rotated through 360 degrees ideally zero tubes which conform to t.i.r tolerances between 0.0059 0.15mm and 0.0005 0.013mm will spin reliably and provide increasingly improved resolution failure to meet concentricity tolerances will result in sample volumes which cross magnetic field flux lines experience magnetic field gradients and contribute to reduced resolution along with modulation sidebands camber a measure of the lack of straightness of a tube this tolerance is determined by gauging the deflection at the middle of a tube held at the ends and rotated through 360 degrees recorded as a deviation ± or total indicator reading t.i.r i.e the absolute value of the deflection range tubes with deviations <0.002 in camber can be expected to spin reliably higher operating field strengths have placed greater importance on the camber of tubes in recent years and stricter tolerances have been required to meet the needs of instrument manufacturers failure to meet camber requirements leads to a marked increase in the intensity of modulation sidebands particularly harmful at higher fields and damage to the probe since only 300 microns separate the tube and insert in most probes meeting strict camber tolerances is the single most important criterion in maintaining the integrity of the probes in your nmr spectrometer outside diameter o.d and inside diameter i.d a measure of the distance across the center of the tube from the two outer surfaces o.d or inner surfaces i.d determined at a large number of points along the tube length best described as a range of numbers we gauge these dimensions fluimetrically meeting stringent standards for o.d and i.d assures the sample tube defines a precisely reproducible cylindrical volume within the rf coils diameters vary over a range that is usually <0.001 0.026mm because these dimensions can vary in many ways failure to adhere to strict tolerances can produce a diversity of undesirable effects on your nmr spectra if the i.d is large vortex plugs may slip from place if small these plugs could burst the tube when the o.d is too small the tube may not fit the turbine snugly causing the tube to wobble upon spinning worse is when the o.d is large for the spinning tube may graze the inside surface of the probe insert ii www.wilmad-labglass.com

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