Food Sci. Biotechnol. 22(6): 1567-1571 (2013) DOI 10.1007/s10068-013-0252-0 Method Validation of 16 Types of Structural Amino Acids using an Automated Amino Acid Analyzer You-Shin Shim, Won-Jin Yoon, Jaeho Ha, Dongwon Seo, Kwang-Won Lee, Woo-Young Lee, Kwang-Il Kwon, Tae-Seok Kang, Jin-Ha Lee, Hyun-Jeong Kim, Hae-Jung Kwak, Sam-Pin Lee, So-Jung Kim, Won-Kap Yun, Junsoo Lee, and Jin-Bong Hwang Received: 16 January 2013 / Revised: 23 April 2013 / Accepted: 15 May 2013 / Published Online: 31 December 2013 © KoSFoST and Springer 2013 Abstract An analytical method for the simultaneous determination of 16 types of structural amino acids in infant formula using an automated amino acid analyzer was validated through tests of precision, accuracy and linearity. The automated analysis of the amino acids was performed on an ion-exchange packed column with a visible detector. The certificated reference material (CRM) 1546 from NIST was used as the test sample to determine the precision and accuracy of the analytical method. The regression analyses revealed good correlations [correlation coefficient (r 2 )] that were greater than 0.99. The recovery values of the amino acids were ranged from 87.18 to 118.08%. The limits of detection and limits of quantification were less than 0.059 mg/100 g and less than 0.198 mg/ 100 g, respectively. The intra- and inter-day precisions were less than 14.62% in the CRM sample. Keywords: amino acids, automated amino acid analyzer, analytical method, validation, post column reaction Introduction Amino acids are biologically important organic compounds composed of amine (-NH 2 ) and carboxylic acid (-COOH) functional groups and a side-chain that is specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen. There are approximately 500 known amino acids (1). Amino acids are one of the most important types of natural compounds because they participate in many essential and well-known physiological processes. One of these processes is the construction of peptides and proteins, in which 20 alpha-amino acids participate (2). Amino acids are investigated in numerous research fields. Within these research fields, there are two primary fields that analyze amino acids. One of these fields is proteomics, and the other field is protein engineering. Proteomics is the large-scale study of proteins, particularly their structures and functions. The goal of proteomics is to provide a comprehensive, quantitative description of protein expression and its changes under the influence of biological You-Shin Shim, Won-Jin Yoon, Jaeho Ha, Dongwon Seo, Jin-Bong Hwang () Food analysis Center, Korea Food Research Institute, Gyeonggi 463-746, Korea Tel: +82-31-780-9128; Fax: +82-31-780-9280 E-mail: hwangjb@kfri.re.kr Won-Jin Yoon, Kwang-Won Lee College of Life Sciences and Biotechnology, Korea University, Seoul 136- 701, Korea Woo-Young Lee Nutrition Safety Policy Division, Food Nutrition and Dietary Safety Bureau, Ministry of Food and Drug safety, Chungbuk 363-700, Korea Kwang-Il Kwon Dietary Life Safety Division, Food Nutrition and Dietary Safety Bureau, Ministry of Food and Drug safety, Chungbuk 363-700, Korea Tae-Seok Kang, Jin-Ha Lee Nutrition and Functional Food Research, Food safety Evaluation Department, National Institute of Food and Drug safety Evaluation, Chungbuk 363-700, Korea Hyun-Jeong Kim, Hae-Jung Kwak, Sam-Pin Lee The Center for Traditional Microorganism Resource, Keimyung University, Daegu 704-701, Korea So-Jung Kim, Won-Kap Yun Gyeongbuk Institute for Marine Bioindustry, Gyeongbuk 767-813, Korea Junsoo Lee Department of Food Science and Technology, Chungbuk National University, Chungbuk 361-763, Korea RESEARCH NOTE