Indirect Enantioseparation of Amino Acids by CE Using Automated In-Capillary Derivatization with ortho-Phthalaldehyde and N-Acetyl-l-Cysteine

详细信息    查看全文

• 作者：Raphael Kühnreich ; Ulrike Holzgrabe
• 刊名：Chromatographia
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：79
• 期：15-16
• 页码：1013-1022
• 全文大小：1,082 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Analytical Chemistry
  Organic Chemistry
  Pharmacy
  Biochemistry
  Plant Sciences
  Measurement Science and Instrumentation
  
• 出版者：Vieweg Verlag
• ISSN：1612-1112
• 卷排序：79

文摘

A simple CE method for the assessment of enantiomeric purity of individual amino acids (AAs) is presented. The AAs were derivatized with ortho-phthalaldehyde and a thiol in the capillary by means of successive hydrodynamic injections (5 s, 0.5 psi) of derivatization solution, sample and derivatization solution. A voltage of 1 kV was applied to blend the solutions and to start the reaction. Subsequently, the derivatives were separated using a background electrolyte (BGE) composed of 50 mM borate buffer (pH = 9.25) and 7.5 mM of a cyclodextrin (CD). To find the optimal derivatization reagent and CD, the impact of the thiols 3-mercaptopropionic acid (MPA), N-acetyl-l-cysteine (NAC) and N-isobutyryl-l-cysteine (NIBLC), and various neutral and negatively charged CDs on the resolution were assessed. The use of NAC and γ-CD enabled the best indirect enantioseparation of 16 AAs. Serine could be separated with β-CD, and proline and cysteine are not suitable for automated OPA-derivatization. The resolutions were ranging from 2.3 to 16.6. A method was validated representative for the AAs methionine, aspartic acid, tryptophan and phenylalanine. The recovery (n = 3) of the minor enantiomers was found to be within 95.1 and 107.5 %. The relative standard deviation (RSD) was ranging from 1.2 to 6.4 %. The method is accurate, precise, linear, and robust. For methionine it could be demonstrated that the ratio of l- and d-AA ranging from 1 to 99 % can be evaluated by direct comparison of the corrected peak areas with satisfactory accuracy ranging between 92.1 and 115.9 %.KeywordsCapillary electrophoresisIndirect enantioseparationAmino acidsOPA derivatizationCyclodextrinsEnantiomeric purity