Improved method for simultaneous determianton of L-arginine and its mono- and dimethylated metabolites in biological samples by high-performance liquid chromatography

摘要

An improved method has been developed for the determination of L-arginine and its methylated metabolites, NG - monomethyl-L-arginine (L-NMMA), NG ,NG-dimethyl-L-arginine (asymmetric DMA, ADMA) and NG ,NG'-dimethyl-L-ar- ginine (symmetric DMA, SDMA) in biological samples. Extraction of these compounds with a strong cation-exchange resin AG50W-X8 with L-homoarginine (2-amino-6-guanidinohexanoic acid) as an internal standard gave a recovery of more than 70% except for SDMA from plasma samples. After extracted samples were converted to fluorescent derivatives with o-phthalaldehyde (OPA) in an alkaline medium, the following high-performance liquid chromatographic separation with a ODS column (wide-pore size, 300 A) was successfully performed with an isocratic mobile phase system. The method permits quantitative determination of L-arginine and its methylated metabolites at concentrations as low as 4 IJ.M and 0.18 IJ.M, respectively. Using this method, the levels of L-arginine, L-NMMA, ADMA and SDMA in human plasma, urine and raj tissue were determined.