title: Investigation and application of photochemically induced direct UV detection of low or non-UV absorbing compounds by capillary electrophoresis.
abstract: Some low or non-UV absorbing compounds like amino acids might be accessible to direct UV detection by capillary electrophoresis (CE), due to the photochemical reaction in the detection window of the separation capillary under extremely strong alkaline conditions. However, with regards to the photochemical reaction procedure and the influencing factors in CE, no comprehensive studies have been done. Herein, two strategies were applied to investigate the photochemical reaction mechanism including the introduction of an additional UV lamp and the utilization of driving pressure. The former confirmed the occurrence of photolysis, while the latter solved the interference of electroosmotic flow (EOF). Furthermore, the online photochemical reaction and online preconcentration technique were combined to develop a rapid, simple and sensitive method for determination of seven essential amino acids (valine, leucine, phenylalanine, methionine, tryptophan, threonine and lysine). Eventually, the developed method was successfully applied to the analysis of real samples with good reproducibility and reliability. This novel and simple method, based on the photochemical reactions occurring in the detection window and coupling with online preconcentration techniques, shows a great potential for the rapid and sensitive detection of low or non-UV absorbing compounds.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Xia
authors.initials: X
authors.lastname: Xie
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Chang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
authors.forename: Meixian
authors.initials: M
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China. Electronic address: zwzhu@pku.edu.cn.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Zhu
keywords: Amino acid; Capillary electrophoresis; Low or non-UV absorbing compounds; Photolysis; UV detection