Fast derivatization of the non-protein amino acid ornithine with FITC using an ultrasound probe prior to enantiomeric determination in food supplements by EKC.
An EKC method for the determination of ornithine (Orn) enantiomers has been developed after a fast pre-capillary derivatization with FITC. The derivatization step was needed to provide a chemical moiety to the Orn molecule, enabling a sensitive UV detection and the interaction with the CDs used as chiral selectors. To accelerate the derivatization reaction, an ultrasound probe was used. For the development of the chiral method, the influence of different experimental conditions (type and concentration of the chiral selector, temperature, and separation voltage) was investigated. Due to the anionic nature of the analyte (FITC-Orn), five neutral CDs were employed as chiral selectors. The native gamma-CD showed the highest chiral separation power, observing that a low concentration of this CD (1 mM), using a working temperature of 25 degrees C and a separation voltage of 20 kV, enabled to obtain the highest enantioresolution for Orn and its separation from other amino acids usually present in food supplements. After optimizing the method for the preconditioning of the capillary, the analytical characteristics of the chiral method were established. Linearity, LOD and LOQ, precision, and accuracy were evaluated previously to the determination of Orn enantiomers contained in ten commercial food supplements. No interferences from other amino acids present in these samples were observed.
Domínguez-Vega
Elena
E
Department of Analytical Chemistry, Faculty of Chemistry, University of Alcalá, Ctra. Madrid-Barcelona, Alcalá de Henares, Madrid, Spain.
Martínez-Girón
Ana Belén
AB
García-Ruiz
Carmen
C
Crego
Antonio L
AL
Marina
María Luisa
ML
D000596:Amino Acids / Q000737:chemistry; D053801:Capillary Electrochromatography; D003505:Cyclodextrins / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis*; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry*; D009952:Ornithine / Q000032:analysis / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D013696:Temperature; D014465:Ultrasonics
D000596:Amino Acids; D003505:Cyclodextrins; D009952:Ornithine; D016650:Fluorescein-5-isothiocyanate