title: Capillary electrophoresis coupled to evaporative light scattering detection for direct determination of underivatized amino acids: application to tea samples using carboxyled single-walled carbon nanotubes for sample preparation.
abstract: An improved and efficient method for the determination of underivatized amino acids based on the use of CE coupled to evaporative light scattering detector (ELSD), involving carbon nanotubes, was successfully developed. Carboxyled single-walled carbon nanotubes were used for the first time to perform the clean-up of the analyzed samples, which were afterwards analyzed by CE-ELSD. White tea samples were used to demonstrate the usefulness of the CE-ELSD coupled methodology. A suitable interface, based on a triple tube design sprayer, was developed and successfully used for coupling both instruments. Parameters affecting the separation and determination, including the elimination of interferences, were studied and properly optimized. Under the optimized conditions good resolution was achieved for the separation of seven amino acids. The precision of the method, expressed as RSD, was found within the 3.5-5.3% range. The LOD obtained for the proposed method were in the 1.2-2.1 pg range and the LOQ, were in the 2.0-11.5 pg range, with injection pressure of 5 KPa for 20 s (15.3 nL). This method is simple, rapid, and selective compared with other conventional techniques.
authors.affiliation: Department of Analytical Chemistry and Food Technology, University of Castilla-La Mancha, Ciudad Real, Spain; Ecole nationale de sciences appliquées, Agadir, Morocco.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bouri
authors.forename: Rachid
authors.initials: R
authors.lastname: Salghi
authors.forename: Mohammed
authors.initials: M
authors.lastname: Zougagh
authors.forename: Angel
authors.initials: A
authors.lastname: Ríos
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D008027:Light; D057230:Limit of Detection; D016014:Linear Models; D037742:Nanotubes, Carbon / Q000737:chemistry*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D013662:Tea / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D037742:Nanotubes, Carbon; D013662:Tea
keywords: CE-ELSD interface; Carboxyled carbon nanotubes; Tea samples; Underivatized amino acids