tailieunhanh - Real-time, on-line monitoring of organic chemical reactions using extractive electrospray ionization tandem mass spectrometry

Corn gluten meal is a natural pre-emergent fertilizer () that reduces the germination and establishment of troublesome annual weeds. It is available as a powder or in granular form. It is 60 percent protein and approximately 10 percent nitrogen by weight. It is a by-product of the wet milling process and commonly used in pet and livestock feed. It can be used in vegetable gardens as a fertilizer and can help with weed control, but be careful. It can damage the germination of your food crops. Use it only after your vegetable seeds are up and young plant roots are. | RCM RAPID COMMUNICATIONS IN MASS SPECTROMETRY Rapid Commun. Mass Spectrom. 2008 22 2993-2998 Published online in Wiley InterScience DOI Real-time on-line monitoring of organic chemical reactions using extractive electrospray ionization tandem mass spectrometry Liang Zhu1 Gerardo Gamez1 Huan Wen Chen2 Hao Xi Huang1 Konstantin Chingin1 and Renato Zenobi1 1Department of Chemistry and Applied Biosciences ETH Zurich CH-8093 Zurich Switzerland 2Department of Applied Chemistry East China Institute of Technology Fuzhou 344000 P R. China Received 13 June 2008 Revised 31 July 2008 Accepted 31 July 2008 Extractive electrospray ionization mass spectrometry EESI-MS for real-time monitoring of organic chemical reactions was demonstrated for a well-established pharmaceutical process reaction and a widely used acetylation reaction in the presence of a nucleophilic catalyst 4-dimethylaminopyridine 4-DMAP . EESI-MS provides real-time information that allows us to determine the optimum time for terminating the reaction based on the relative intensities of the precursors and products. In addition tandem mass spectrometric MS MS analysis via EESI-MS permits on-line validation of proposed reaction intermediates. The simplicity and rapid response of EESI-MS make it a valuable technique for on-line characterization and full control of chemical and pharmaceutical reactions resulting in maximized product yield and minimized environmental costs. Copyright 2008 John Wiley Sons Ltd. Obtaining comprehensive information on chemical reactions is crucial for the characterization of reaction mechanisms as well as the maximization of production efficiency in the chemical and pharmaceutical industries. Usually detection of process deviations and prompt modification of reaction conditions are key to achieving the best control of chemical reactions. However this demands techniques that are suited for real-time on-line monitoring of the chemical reaction .