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Learning Polymer Materials Analysis from Natural Lacquer (Urushi)

Introduction: In recent years, polymer materials have become more complex due to increased composition and diversification so that a one-sided analysis is insufficient and multifaceted observations and analyses are required. In response to this need, JEOL has engaged in applied research under the keyword of "YOKOGUSHI" (multifaceted cross-instrumental) using various instruments organically. In this Urushi Note, multifaceted analysis methods for polymer materials are illustrated using the examples of natural lacquer (urushi) analysis.

Sample tube grade affects resolution

Some low-grade, inexpensive NMR sample tubes have large warpage, low wall thickness uniformity, and large distortion, which may adversely affect the resolution. The effect of low-grade sample tubes, such as disposable ones, on the resolution is small in low-field NMR, but it may be noticeable in high-field NMR. In addition, some disposable sample tubes are thicker or thinner than the nominal value and will not fit in the sample holder.

Structural analysis of PET combining an on-plate alkaline degradation method & tandem TOFMS - MSTips 311

We investigated the structural analysis of the polyethylene-terephthalate (PET) polymer exposed to the on-plate alkaline degradation method by using the JMS-S3000 "SpiralTOFTM-plus" with TOF-TOF option. The SpiralTOFTM-plus uses an ultra-high resolution TOF for MS1 which allows monoisotopic precursor selection and a reflectron TOF for MS2 to analyze the product ion spectra produced from high energy collisional induced dissociation (HE-CID).

NOAH-NMR Supersequences with Nested Acquisition for Small Molecules

NOAH (NMR by Ordered Acquisition using 1H-detection)[1] is a group of nested NMR experiments combining several conventional two-dimensional (2D) NMR pulse sequences, such as COSY, HSQC and HMBC, into one supersequence. Therefore, two or more 2D NMR data can be obtained from a single NOAH experiment. By using a single relaxation delay, the NOAH method significantly reduces the total data collection time and increases the throughput of an NMR instrument in structure elucidation of small organic molecules.

High Resolution 2D spectra

13C NMR spectra provide wide range chemical shift, and it suggests that can easily distinguish each signals. But carbon resolution of 2D spectra such as HSQC and HMBC is worse than 1D 13C spectra due to small data points. In order to analyze a compound with close 13C chemical shifts, a high resolution 2D spectrum is required frequently. In this document, some improvements to distinguish each signals on 13C axis of 2D hetero nuclear experiments are presented.

Study of Chemical Exchange by 2D NMR

The NMR signal of a spin reflects its local magnetic environment. If a spin due to chemical exchange samples two magnetically different states then its NMR signal would reflect both states. Its appearance on a NMR spectrum would be determined by the dynamics of the exchange event. In the case of chemical exchange that is slow on the NMR time scale, it is possible to observe two distinct signals for the same spin, one signal for each state under exchange. Presence of chemical exchange is often demonstrated with the exchange experiment (2D NOESY experiment). A exchange peak (cross peak) of the same sign can be observed between the two autopeaks (diagonal peaks) that represent the two states under exchange. Because the same results can be interpreted in a different way based on NOE, further evidence is desirable.

Other Resources

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Media

Corona - Glow Discharge (DART Ion Source)

February 22, 2020
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