Analysis of Amino Acids, Including Taurine, in Plasma of Cats Using High-Performance Liquid Chromatography with Fluorescence Detection

Abstract

Amino acids play essential roles in mammals, and their analysis in biological samples can provide valuable physiological insights. Recently, interest in health management has expanded, encompassing humans and companion animals. This study aimed to develop a high-performance liquid chromatography-fluorescence method to analyze plasma amino acids in cats—the most popular companion animals. Unlike humans, cats cannot synthesize taurine, an essential biomolecule for their health that must be acquired through external dietary sources. We developed a method for the simultaneous analysis of taurine and amino acids. 4-Fluoro-7-nitro-2, 1, 3-benzoxadiazole was used as a fluorescence derivatization reagent owing to its advantages, such as the formation of stable derivatives and high reaction efficiency. The separation conditions were optimized, and 16 amino acids, including taurine, were successfully separated. The developed method demonstrated good validation data in amino acid standards and cat plasma samples and was applied to assess cat plasma samples obtained from healthy cats and those with a history of ureterolithiasis. The plasma concentrations of glutamic acid, taurine, and citrulline were significantly elevated in cats with a history of ureterolithiasis. The analytical method developed in this study could be valuable for exploring the relationship between plasma amino acids and cat health.