title: High-performance liquid chromatography with fluorescence detection for quantitation of tryptophan and tyrosine in a shrimp waste protein concentrate.
abstract: A new, simple, and reproducible isocratic high-performance liquid chromatography (HPLC) method has been developed for the determination of free and total tyrosine and tryptophan in a protein concentrate. To determine total amino acids, the method involves alkaline hydrolysis of the proteins with sodium hydroxide at 120 degrees C for 4h in the absence of air. Best results were achieved with a SS Exil ODS column 5microm (25cmx0.46cm i.d.), with an eluent of methanol: 40mM sodium acetate buffer (adjusted to pH 4.5 with acetic acid; 20:80, v/v), a flow rate of 0.80mL/min at 26 degrees C, and with programmable fluorescence detection. Under optimum conditions excellent linearity was obtained, and the overall recovery was 90.5, and 95.9% for total tryptophan and tyrosine, respectively. The precision results showed that the relative standard deviation of the repeatability and reproducibility were < or =4.78 and < or =4.65, respectively. This method was used to quantify the cited analytes in the protein concentrate obtained during the lactic acid fermentation of shrimp waste.
authors.affiliation: Departamento de Biotecnología y Ciencias Alimentarias, Instituto Tecnológico de Sonora, 5 de febrero 818 Sur, CP 85000, Ciudad Obregón, Sonora, Mexico.
authors.forename: D I
authors.initials: DI
authors.lastname: Sánchez-Machado
authors.forename: B
authors.initials: B
authors.lastname: Chavira-Willys
authors.forename: J
authors.initials: J
authors.lastname: López-Cervantes
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D005511:Food Handling; D006868:Hydrolysis; D033561:Penaeidae / Q000737:chemistry*; D011506:Proteins / Q000032:analysis*; D012015:Reference Standards; D015203:Reproducibility of Results; D012758:Shellfish / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000032:analysis*; D014443:Tyrosine / Q000032:analysis*; D014866:Waste Products / Q000032:analysis*
chemical_list: D011506:Proteins; D014866:Waste Products; D014443:Tyrosine; D014364:Tryptophan