Direct UV detection of underivatized amino acids using capillary electrophoresis with online sweeping enrichment

• Published in: Journal of separation science 2009-06, Vol.32 (11), p.1927-1933
• Main Authors: Jiang, Xuemei, Xia, Zhining, Wei, Weili, Gou, Qian
• Format: Article
• Language: English
• Subjects: Amino acids; Amino Acids - analysis; Amino Acids - chemistry; Analytical chemistry; Biological and medical sciences; Capillary electrophoresis; Chemistry; Chromatographic methods and physical methods associated with chromatography; Coffee, tea and other stimulative beverage industries; Coordination interaction; Copper - chemistry; Direct UV detection; Electrophoresis, Capillary - instrumentation; Electrophoresis, Capillary - methods; Exact sciences and technology; Food industries; Fundamental and applied biological sciences. Psychology; Humans; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Miscellaneous. Technology; Online sweeping; Osmolar Concentration; Other chromatographic methods; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Plant Extracts - chemistry; Reproducibility of Results; Saliva - chemistry; Sensitivity and Specificity; Solutions; Tea - chemistry; Time Factors; Ultraviolet Rays
• ISSN: 1615-9306; 1615-9314
• DOI: 10.1002/jssc.200900013

This is an original report proposed a CE method for direct analysis of the underivatized amino acids using UV detection with relatively higher sensitivity, which was based on coordination interactions between amino acids and Cu (II) ions. In addition, an online sweeping preconcentration technique was easily combined to improve the detection sensitivity. Satisfying separations of the amino acids were obtained under optimized conditions: 50 mmol/L CuSO₄-0.05% HAc-H₂O (pH 4.5), and the separation voltage of 15 kV. The LODs for the analytes ranged from 0.1 to 0.5 μmol/L. The linearity of detection for all analytes was two orders of magnitude with the correlation coefficients greater than 0.99. The repeatability was displayed with an RSD less than 3% for migration time and peak height (n = 5). Moreover, some amino acids in real samples of human saliva and green tea were analyzed by this direct UV detection CE method with acceptable sensitivity.