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Development of 19F‐detected 1,1‐ADEQUATE for the characterization of polyfluorinated and perfluorinated compounds

Polyfluorinated and perfluorinated compounds in the environment are a growing health concern. 19F‐detected variants of commonly employed heteronuclear shift correlation experiments such as heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC) are available; 19F‐detected experiments that employ carbon–carbon homonuclear coupling, in contrast, have never been reported. Herein, we report the measurement of the 1JCC and nJCC coupling constants of a simple perfluorinated phthalonitrile and the first demonstration of a 19F‐detected 1,1‐ADEQUATE experiment.

Separation of 13C spectra of polyurethane soft and hard segments by ROSY_NM200013E

The ROSY (Relaxation Ordered SpectroscopY) is a method in which the 13C CPMAS spectrum of a mixture is classified by a longitudinal relaxation time of 1H, and the 13C CPMAS spectrum is displayed separately for each substance. In solution NMR, each peak in the 1H spectrum has its own longitudinal relaxation time. In solid-state NMR, however, spin diffusion occurs due to the dipolor interaction between 1H, and all 1H have the same longitudinal relaxation in the domain within a certain distance. The 13C spectrum can be separated for each domain by using this difference in relaxation time of 1H. The longitudinal relaxation time (T1H) obtained by the saturation recovery method as shown in Fig.1a is usually used to separate the 13C spectrum of the mixture. The size of the domain that can be separated by this method is about 100 nm. To separate domains smaller than this, a measurement using the relaxation time at rotational flame (T1ρH) obtained by the spinlock method as shown in Fig.1b is effective. The domain size that can be separated by T1ρH is about several nm, and it is possible to determine the phase separation structure of block copolymers and the molecular compatibility.

The Use of Dispersive Solid Phase Extraction in the Detection of Pesticides in Cannabis Flower by GC-MS/MS

This study presents a comprehensive method for the analysis of gas chromatograph (GC)-amendable pesticides in Cannabis flower. Furthermore, this method uses dispersive solid phase extraction (dSPE) to help mitigate matrix effects that are common in the flower extract. Three selected reaction monitoring (SRM) transitions were used for each target pesticide. This study was focused on developing a robust and sensitive method for GC amendable pesticides in Cannabis flower for use in the state of California. However, LC-MS/MS would also be required to analyze the complete California pesticide list.

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Corona - Glow Discharge (DART Ion Source)

January 28, 2022
2343