High performance liquid chromatography was applied for the determination of tryptophan in food. The sample was hydrolyzed in a duration from 16 to 24 hour by protease enzyme at 50 oC. The extract was separated on the C8 reversed phase column with mobile phase of NaH2PO4 50mM pH 2.3: Methanol (82:18; v/v). The linearity of the method was kept in the range of 0.5 - 50 mg/L. Limit of detection was found to be 4.6 mg/100g. Recovery was determined by standard addition method, giving values of recovery in the range of 97 - 103% and RSD (n = 6) in the range of 0.077 - 2.27%. Internal standard was used to reduce the errors in analysis process and good reproducibility.
HPLC, Tryptophan, food, amino acid
1. TCVN 5283:2007 – Determination of tryptophan in feed by HPLC method.
2. Nguyen Xuan Truong, Pham Thi Thuy, Nguyen Thi Anh Huong (2017), “Study on fluores cence kinetics method for simultaneous determination of tyrosine and tryptophan based on polypyridin ruthenium (II) complex reaction” Tạp chí phân tích Hóa, Lý và Sinh học – Vol 22, No 3/2017.
3. Tran Cao Son (2010), “Method validation in analysis of chemistry and microbiology”, Poublishing house of Science and Technology, Hanoi..
4. Critima Delgado-Andrade, José A. Rùián-Henares, Salvio Jiménez-Pérz, Francisco J. Morales, (2006). “Tryptophan determination in milk – based ingredients and dried sport supplements by liquid chromatography with fluorescence detection” Food Chemistry 98, 580–585.
5. Estefanía Jimenez-Mart ́ ín, Jorge RuizTrinidad Perez-Palacios, Antonio Silva, Teresa Antequera (2012). “Gas Chromatography−Mass Spectrometry Method for the Determination of Free Amino Acids as Their Dimethyl-tert-butylsilyl (TBDMS) Derivatives in Animal Source Food” Journal of Agricultural and Food Chemistry 60, 2456−2463.
6. Jiaoyan Ren, Mouming Zhao, Jinshui Wang, Chun Cui and Bao Yang (2007). “Sectrophoto metric method for determination of Tryptophan protein hydrolysates” Food Technol. Biotechnol 45 (4) 360 - 366.
7. Lijuan Song a, Zhenpeng Guo a, Yi Chen (2011). “One-pot labeling-based capillary zoneelectrophoresis for separation of amino acid mixture and assay of biofluids” Analytica Chimica Acta 703, 257–263.
8. O. Draher and N. White (2018). “HPLC Determination of Total Tryptophan in Infant Formula and Adult/Pediatric Nutritional Formula Following Enzymatic Hydrolysis: Single-Laboratory Validation, First Action 2017.03” Juornal of AOAO international, Volume 101, pp. 824-830(7).
9. Yonghong Zhu, Yan Yang, Zhaoxu Zhou, Genrong Li, Mei Jiang, Chun Zhang, Shiqi Chen (2010). “Direct determination of free tryptophan contents in soy sauces and its application as an index of soy sauce adulteration” Food Chemistry 118, 159–162.