Development of an in‐capillary derivatization method by CE for the determination of chiral amino acids in dietary supplements and wines

Abstract

A fast in-capillary derivatization method by CE with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate was developed for the first time for the determination of amino acid enantiomers (arginine, lysine, and ornithine) in dietary supplements and wines. Because of the initial current problems due to the formation of precipitates into the capillary during the derivatization reaction, a washing step with an organic solvent as DMSO between injections was necessary. Different approaches were also investigated to enhance the sensitivity of detection. A derivatization procedure, where plugs of ACN, derivatizing agent (10 mM 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate), and sample in borate (1:1 v/v) were injected in tandem (2, 3, and 6 s, respectively, at 50 mbar), was selected because it enabled to obtain the most sensitive and reproducible results. Appropriate analytical characteristics (linearity, LOD and LOQ, precision, absence of matrix interferences, and accuracy) were obtained for this method. Finally, the optimized method was successfully applied to the determination of the enantiomers of arginine, lysine, and ornithine in food samples of different complexities (dietary supplements and wines).

Development of a CE‐ESI‐ITMS method for the enantiomeric determination of the non‐protein amino acid ornithine

“…Thus, several works have reported the enantiomeric separation of Orn by CE [15][16][17][18][19]. Some of them have been developed in our research group, reaching analysis times lower than 15 min, even showing their potential in food analysis [17][18][19].…”

Capillary electrophoresis determination of non-protein amino acids as quality markers in foods

“…As shown in Fig. 6, the methodology allowed the enantiomeric separation of ornithine (in less than 15 min) as well as the separation of the enantiomers of this amino acid from the enantiomers of the chiral amino acids contained in a mixture of the twenty protein amino acids and GABA in about 45 min To short the analysis time and to increase CE method automatization, the same authors developed a second method using in-capillary derivatization [66] with the aim of determining Orn, arginine and lysine enantiomers in wine samples (this compounds have demonstrated to be responsible of wine's organoleptic ACN, acetonitrile; Ac-␥-CD, acetylated-␥-CD; AQC, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate; Arg, arginine; Asp, asparagine; GABA, ␥-aminobutiric acid; ␥-CD, ␥-cyclodextrin; FITC, fluorescein isothiocyanate; FMOC, 9-fluorenylmethoxycarbonylchloride; HS-␤-CD, highly sulfated-␤-cyclodextrin; Lys, lysine; MS 2 , tandem mass spectrometry; PFT, partial filling technique; Succ-␥-CD, succinyl-␥-cyclodextrin; TCA, trichloroacetic acid. * Capillary dimension expressed as internal diameter × effective length (cm to the detector).…”

Nutritional and medicinal aspects of d-amino acids

“…Analytical methods were developed for Orn isomers that may be present in processed foods (Martínez-Girón et al 2008;Martínez-Girón et al 2009). D-Ornithine (D-Orn) has been found in nature on few occasions.…”