Abstract: The present invention provides a highly versatile method for amino acid analysis, the method enabling separation and analysis of amino acids in a sample with high precision in a shorter time. This method is a method for amino acid analysis, the method including a step of allowing a sample containing a plurality of amino acids to flow together with an eluent 2 through a separation column 4 packed with a cation exchange resin, thereby separating the amino acids, and a step of detecting the separated amino acids, wherein the eluent 2 is an eluent containing a divalent or higher inorganic acid, a cation source, and water, and having a pH of 5.0 or lower, and the sample is allowed to flow through the separation column 4 heated by applying a temperature gradient including a temperature region of 100° C. or higher.

Abstract: Disclosed herein are an amino acid analysis method and a liquid chromatographic apparatus for improving separation performance of threonine, serine, glycine, and alanine. The method of analyzing amino acids using the liquid chromatographic apparatus equipped with a cation exchange column includes a process for distributing a sample containing threonine, serine, glycine, and alanine as the amino acids, together with an eluent, to the cation exchange column to separate threonine, serine, glycine, and alanine, wherein a column temperature when separating threonine and serine is higher than a column temperature when separating glycine and alanine.

Abstract: The present invention provides a highly versatile method for amino acid analysis, the method enabling separation and analysis of amino acids in a sample with high precision in a shorter time. This method is a method for amino acid analysis, the method including a step of allowing a sample containing a plurality of amino acids to flow together with an eluent 2 through a separation column 4 packed with a cation exchange resin, thereby separating the amino acids, and a step of detecting the separated amino acids, wherein the eluent 2 is an eluent containing a divalent or higher inorganic acid, a cation source, and water, and having a pH of 5.0 or lower, and the sample is allowed to flow through the separation column 4 heated by applying a temperature gradient including a temperature region of 100° C. or higher.

Abstract: A method of determining a cationic surfactant in a sample solution, characterized by passing the sample solution through a disk containing styrene/divinylbenzene copolymer particles and a disk containing an anion-exchange resin; and then subjecting the resultant solution to high-performance liquid chromatography. The method of the present invention enables separation/quantification of CS in river water or lake water which also contains inorganic ions and AS of high concentration, even when the CS content is below the order of ppb.