A CRITICAL-ASSESSMENT OF BRAIN-METABOLITES - ANALYSIS OF PERCHLORIC-ACID EXTRACTS USING PROTON NUCLEAR-MAGNETIC-RESONANCE

A critical assessment of perchloric acid (PCA) brain tissue extracts f or precise identification and quantitation of brain metabolites using in vitro proton nuclear magnetic resonance (H-1 NMR) spectroscopy was studied. One pulse with a presaturation NMR experiment was used, The c hemical shifts and coupling networks of the major brain metabolites as a function of pH were characterized by using individual model compoun ds and a model mixture solution. We found that the conditions of the P CA solution are essential for accurate interpretation of NMR spectra o f brain metabolites. The maximum spectral resolution was obtained at p H 4.92. Caution is necessary when using high resolution H-1 NMR spectr oscopy to identify and quantify brain metabolites.