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1.
Chem Commun (Camb) ; 56(31): 4328-4331, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32191244

RESUMO

Vapour-phase surface-initiated cationic polymerisation of ethylvinylether occurs at single-crystals of the σ-alkane complex [Rh(Cy2PCH2CH2PCy2)(NBA)][BArF4]. This new surface interface makes these normally very air sensitive materials tolerant to air, while also allowing for onward single-crystal to single-crystal reactivity at metal sites within the lattice.

2.
Food Chem ; 248: 52-60, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29329870

RESUMO

High-field and low-field proton NMR spectroscopy were used to analyse lipophilic extracts from ground roast coffees. Using a sample preparation method that produced concentrated extracts, a small marker peak at 3.16 ppm was observed in 30 Arabica coffees of assured origin. This signal has previously been believed absent from Arabicas, and has been used as a marker for detecting adulteration with robusta. Via 2D 600 MHz NMR and LC-MS, 16-O-methylcafestol and 16-O-methylkahweol were detected for the first time in Arabica roast coffee and shown to be responsible for the marker peak. Using low-field NMR, robusta in Arabica could be detected at levels of the order of 1-2% w/w. A surveillance study of retail purchased "100% Arabica" coffees found that 6 out of 60 samples displayed the 3.16 ppm marker signal to a degree commensurate with adulteration at levels of 3-30% w/w.


Assuntos
Café/química , Diterpenos/análise , Análise de Alimentos/métodos , Espectroscopia de Ressonância Magnética/métodos , Coffea/química , Contaminação de Alimentos/análise , Limite de Detecção , Reprodutibilidade dos Testes
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