nmr

Reference Standards Quality in NMR Spectroscopy

Because many conclusions based on NMR spectrometry require optimal performance or a gauge of current spectrometer performance, spectroscopists have come to rely upon the spectra of certain carefully prepared chemical mixtures to evaluate and compare performance characteristics. These mixtures, called Reference Standards or Test Samples, are made in a myriad of recipes to cover different nuclei, concentration ranges, performance criteria, and sample or tube sizes, to name a few.

NMR-010:Proper Cleaning Procedures for NMR Sample Tubes

Each individual WILMAD NMR tube, regardless of Precision grade or Economy grade, has gone through a minimum of four step cleaning process, as ultrasonic wash in detergent, ultrasonic wash in distilled water, ultrasonic wash in nano water and hot air dry in a clean room. So each Wilmad NMR has zero NMR background.

NMR-009:Tube Closures and Vortex Plugs in NMR Applications

WILMAD offers an enviable variety of sample tubes for NMR spectroscopists. Often, the difference between one tube and another is simply the closure. To better understand the use of these different tubes and how the closures affect the way each is used, we've assembled information about NMR tube caps, valves, joints, etc. that will help you select NMR tubes that best meet your needs.

NMR-007: Coaxial Inserts in NMR Studies

NMR experiments that involve external reference/lock or that compare two solutions require two well defined sample volumes within the probe. WILMAD makes a variety of unique sampling systems that create such distinct sample volumes. This report will help you select the right insert or coaxial system for experiments where two volumes are needed. Refer to the table on the last page for a summary of the inserts WILMAD makes and what experiments each can be used for.

Challenges in Coaxial NMR Sampling

NMR-006: Valve Tubes and Air Sensitive Samples in NMR

It isn't surprising that considerable attention is directed toward carefully choosing solvents for NMR experiments. Today, solvents must provide an effective medium in which to dissolve a sample to the required concentration and filling-factor . . . must contribute no interfering resonances . . . and must provide a lock signal to assure spectrometer stability. This presents stringent challenges for manufacturers of NMR solvents when added to the obvious need for chemical purity.

NMR-003: Pressure Performance of NMR & EPR Sample Tubes

The application of NMR and EPR techniques to investigations in catalysis and the study of reactions involving gas and liquid phase components has renewed interest in the pressure performance of glass NMR and EPR sample vessels.

WILMAD glass sample devices should not be used in pressure applications before the hazards involved are fully understood. WILMAD does not guarantee the pressure performance of any of its glass sample devices for NMR and EPR spectroscopy.

NMR001: NMR Tube Specifications and Quality

The purpose of an NMR tube is to confine a liquid sample in a perfectly cylindrical volume in a magnetic field. Since this description is based on mechanics, it is not surprising that NMR tubes have been described by structural parameters for many years. The degree to which an NMR sample tube approaches the ideal ‘perfect cylinder’ defines the quality of the NMR tube.