130752-32-8Relevant articles and documents
Pressurized sample infusion: An easily calibrated, low volume pumping system for ESI-MS analysis of reactions
Vikse, Krista L.,Ahmadi, Zohrab,Luo, Jingwei,Van Der Wal, Nicole,Daze, Kevin,Taylor, Nichole,McIndoe, J. Scott
, p. 8 - 13 (2012)
Pressurized sample infusion (PSI) continuously delivers solution from a flask through capillary tubing at a flow rate that makes it suitable as a low internal volume pumping method for electrospray ionization mass spectrometry (ESI-MS). The flow rate can be predicted from the applied pressure by using the Hagen-Poiseuille equation, but variability in internal diameter of the PEEK tubing used is such that each individual length should be calibrated if accurate results are sought. Once calibrated, the values hold well for different solvents across a range of pressures. The technique has been exemplified in two reactions: the deprotection of a protected amino acid using trifluoroacetic acid, and in the platinum-catalyzed redistribution of two silanes. In both cases, the abundances of starting material, product(s) and intermediates were tracked in real time as the reaction proceeded.
Liquid-chromatography quantitative analysis of 20 amino acids after derivatization with FMOC-CI and its application to different origin Radix isatidis
Zhou, Wei,Zhang, Xiao-Yan,Duan, Geng-Li
experimental part, p. 509 - 515 (2012/01/04)
We developed a simple, rapid and reliable method for determination of 20 common amino acids based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-CI) and RP-LC/UV, this method was first introduced into quantitative analysis of amino acids. The amino groups of amino acids were trapped with FMOC-CI to form amino acid-FMOC-Cl adducts which can be suitable for LC-UV. Chromatographic separation was performed on a C18 column with a mobile phase gradient consisting of acetonitrile and sodium acetate solution. This method was shown to be sensitive for 20 common amino acids. In the intra-day precisions assay, the range of RSDs was 3.21-7.67% with accuracies of 92.34-102.51%; for the inter-day precisions assay, the range of RSDs was 5.82-9.19% with accuracies of 90.25-100.63%. The results also indicated that solutions of amino acids-FMOC-Cl can be kept at room temperature for at least 24 h without showing significant losses in the quantified values. The validated method was successfully applied to the determination of major four kinds of amino acids in R. isatidis samples (Arg, Pro, Met and Val). The total content of amino acids in different origin R. isatidis was 13.32-19.16 mg/g. The differences between R. isatidis samples were large using HCA.
Efficient procedure for the preparation of oligomer-free N-fmoc amino acids
Nowshuddin, Shaik,Rao,Reddy, A. Ram
experimental part, p. 2022 - 2031 (2009/11/30)
A two-step method is presented for the peptide-free, high-purity, and high-yield synthesis of N-Fmoc amino acids. The first step involves the preparation of stable dicyclohexylammonium-amino acid ionic adduct in acetone. Subsequently, the ionic adducts, on reaction with Fmoc-Nosu under mild alkaline conditions, give dipeptide-free N-Fmoc amino acids. The positive charge of the dicyclohexylammonium counterion in the ionic salt has a longer radius, moderating the nucleophilicity of the carboxylate ion of the amino acid and preventing by-products by arresting the formation of mixed anhydrides, the precursors of oligopeptide impurities.
