A simple, fast and sensitive protocol was developed for the simultaneous determinations of seven fluorescent whitening agents (FWAs) in polystyrene (PS) and polyvinyl chloride (PVC) plastics involved in food packaging, using ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with positive electrospray ionization and multiple reaction monitoring mode. Sample preparation included dissolution, extraction, and methanol-induced polymer precipitation. All analytes were eluted within 6 min using methanol. The calibration curves were drawn in the range of 0.1-50 mg L À1 for the seven FWAs, with good correlation coefficients (R 2 > 0.995). The detection limits were 0.7-9 mg kg À1 , and the quantitation limits were 2.5-30 mg kg À1 . Recoveries ranged from 81.4% to 116%, with a relative standard deviation (RSD) of 2.9-10.8% (n ¼ 6). Intra-and inter-day precisions (n ¼ 6) were lower than 15%. The UPLC-MS/MS protocol developed in this work was confirmed to be a fast, precise and quantitative technique for the simultaneous determinations of FWAs in PS and PVC plastics.
Streamlining the
generation of diverse highly functionalized molecules
from abundant feedstocks holds great synthetic promises and challenges
in pharmaceutical and material discovery. Herein, we report a tunable
selectivity in multiple cascade reactions for the divergent assembly
of fused N-heterocycles, comprising sequential activation
of C–H and C–C bonds. Isolatable indene-type intermediates
might be responsible for the generation of densely substituted fused
pyridines, azepines, and azafluorenones products. The tolerance of
strongly coordinating N-heterocycles, and those readily
applicable for the late-stage modifications of pharmaceuticals and
material molecules precursors, further demonstrated the synthetic
robustness of this transformation.
An efficient and versatile oxidative coupling reaction was developed for the synthesis of valuable β‐functionalized unsaturated ketones and meta‐substituted phenols. In the case of intramolecular reactions, achieving rapid molecular complexity through multiple dehydrogenative couplings is already a well‐established strategy. Herein, we report an intermolecular multiple dehydrogenative coupling between ketones and nucleophilic amines or boronic acids using inexpensive copper(I) oxide as a catalyst. This method provides a facile access to highly desirable chemical products such as α,β‐unsaturated ketones, enaminones, and synthetically relevant meta‐substituted phenols.magnified image
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