title: High-performance liquid chromatographic on-line flow-through radioactivity detector system for analyzing amino acids and metabolites labeled with nitrogen-13.
abstract: A flow-through radioactivity detector was used for the high-performance liquid chromatographic determination of amino acids and other nitrogenous substances labeled with 13N, a short-lived (t1/2 9.96 min) positron-emitting radionuclide. 13N-Labeled compounds were analyzed using cation, anion and amino columns, or as the o-phthaldialdehyde derivative on an ODS column. Use of column-switching valves and a high-performance liquid chromatographic system with a quaternary eluting capability permits two to three 20-min analyses of labeled samples from a single 13N experiment to be carried out on different columns using a binary or a single mobile phase. Radioactivity in liver metabolites was quantified using an on-line flow-through monitor with data processing capability for integrating peaks and correcting for radioactivity decay. As an example, 1 min following an L-[13N]glutamate injection via the hepatic portal vein, 77% of the label in the liver was in a metabolized form; at least ten labeled products were formed.
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D009590:Nitrogen Radioisotopes; D051381:Rats; D009764:o-Phthalaldehyde
chemical_list: D000596:Amino Acids; D009590:Nitrogen Radioisotopes; D009764:o-Phthalaldehyde