Liquid chromatography-mass standard-free metabolite

Valaskovic, G.A. et al., Ultra-low flow nanospray for the normalization of conventional liquid chromatography/mass spectrometry through equimolar response Standard-free quantitative estimation of metabolite levels in drug discovery, Rapid Commun. Mass Spectrom., 20, 1087, 2006. 

NMR spectra were measured with a Varian Unity 300 FT-NMR spectrometer. Liquid chromatography-atmospheric chemical ionization-mass spectrometry (LC-APCl-MS) in positive and negative ion modes was performed using a Hitachi M-1000 spectrometer. Unknown metabolites were isolated and purified from the grape fruits extracts with solid phase extraction method (Porapak Q) and HPLC. Isolated metabolites were analyzed by free form or derivatized (methylated, acetylated) form for identification. All of the non-radiolabelled reference standards 1-6 are synthesized in our laboratory and their chemical structures are shown in Figure 2. 

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