Measurement of urinary amino acids using high-performance liquid chromatography equipped with a strong cation...

We determined the urinary amino acid concentrations by high-performance liquid chromatography (HPLC) using an eluent buffer which had been processed through a column packed with strong cation-exchange resin. With this column, ghost peaks resolved or much reduced in size and shifted to a post-arginine position. A clearer separation of peaks of urinary amino acids and ammonia was obtained. This could be due to the elimination of O-phthalaldehyde reactive substances in the eluent by the resin column. This method does not require a separate step to remove ammonia, unlike most of the methods currently used, and thus saves time.