title: Enantiomeric separation of non-protein amino acids by electrokinetic chromatography.
abstract: New analytical methodologies enabling the enantiomeric separation of a group of non-protein amino acids of interest in the pharmaceutical and food analysis fields were developed in this work using Electrokinetic Chromatography. The use of FMOC as derivatization reagent and the subsequent separation using acidic conditions (formate buffer at pH 2.0) and anionic cyclodextrins as chiral selectors allowed the chiral separation of eight from the ten non-protein amino acids studied. Pyroglutamic acid, norvaline, norleucine, 3,4-dihydroxyphenilalanine, 2-aminoadipic acid, and selenomethionine were enantiomericaly separated using sulfated-α-CD while sulfated-γ-CD enabled the enantiomeric separation of norvaline, 3,4-dihydroxyphenilalanine, 2-aminoadipic acid, selenomethionie, citrulline, and pipecolic acid. Moreover, the potential of the developed methodologies was demonstrated in the analysis of citrulline and its enantiomeric impurity in food supplements. For that purpose, experimental and instrumental variables were optimized and the analytical characteristics of the proposed method were evaluated. LODs of 2.1×10-7and 1.8×10-7M for d- and l-citrulline, respectively, were obtained. d-Cit was not detectable in any of the six food supplement samples analyzed showing that the effect of storage time on the racemization of citrulline was negligible.
authors.affiliation: Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Biología, Ciencias Ambientales y Química, Universidad de Alcalá, Ctra. Madrid-Barcelona Km. 33.600, 28871 Alcalá de Henares, Madrid, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Pérez-Míguez
authors.affiliation: Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Biología, Ciencias Ambientales y Química, Universidad de Alcalá, Ctra. Madrid-Barcelona Km. 33.600, 28871 Alcalá de Henares, Madrid, Spain.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Marina
authors.affiliation: Departamento de Química Analítica, Química Física e Ingeniería Química, Facultad de Biología, Ciencias Ambientales y Química, Universidad de Alcalá, Ctra. Madrid-Barcelona Km. 33.600, 28871 Alcalá de Henares, Madrid, Spain. Electronic address: maria.castrop@uah.es.
authors.forename: María
authors.initials: M
authors.lastname: Castro-Puyana
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000302:isolation & purification*; D002021:Buffers; D020374:Chromatography, Micellar Electrokinetic Capillary; D002956:Citrulline / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis; D005506:Food Contamination / Q000032:analysis; D061353:Food Storage; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D057230:Limit of Detection; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D002021:Buffers; D007202:Indicators and Reagents; D002956:Citrulline
keywords: Chiral CE; Citrulline; Electrokinetic chromatography; Enantiomeric separation; Food supplements; Non-protein amino acids