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Separation and detection of angiotensin peptides by Cu(II) complexation and capillary electrophoresis with UV and electrochemical detection
Author(s) -
Lacher Nathan A.,
Garrison Kenneth E.,
Lunte Susan M.
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200206)23:11<1577::aid-elps1577>3.0.co;2-4
Subject(s) - capillary electrophoresis , detection limit , angiotensin ii , chemistry , chromatography , copper , captopril , angiotensin iii , electrochemistry , electrophoresis , angiotensin converting enzyme , angiotensin receptor , biochemistry , electrode , medicine , receptor , organic chemistry , blood pressure
The use of capillary electrophoresis (CE) with on‐capillary Cu(II) complexation for the determination of angiotensin and its metabolites is described. The resulting copper‐peptide complexes can be detected using either UV or electrochemical (EC) detection. Optimal reaction and separation conditions for the angiotensin peptides were first determined using CE with UV detection. With UV detection, the limit of detection (signal‐to noise ratio S/N = 3) for native angiotensin II was 18 ν M , while the limit of detection (LOD) obtained for the copper‐angiotensin II complex is 2 ν M . CE with EC detection was then evaluated, yielding significantly lower LODs – 2 ν M for native angiotensin II and 200 n M for the copper‐angiotensin II complex. The addition of copper to the run buffer improved the separation and sensitivity for both CE‐UV and CE‐EC detection. The method was demonstrated by monitoring the conversion of angiotensin I to angiotensin II in plasma via angiotensin‐converting enzyme (ACE) and subsequent inhibition of ACE by captopril.