A monolithic microcolumn modified with iron-protoporphyrin IX coupled to capillary electrophoresis allows an outstanding increase in detection sensitivity for angiotensin I

YONE A; RUSELL ML; BRUNO D; PEREZ SE; VIZIOLI NM

Querétaro, México

Simposio; 12th Symposium on Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2006

The use of affinity compounds for specific selection of analytes present in different complex samples on-line with capillary electrophoresis has become increasingly important, in particular regarding protein and peptide analysis. Here, an online preconcentration method using a polymeric monolithic support is proposed for the retention of decapeptide angiotensin I and its subsequent separation by capillary zone electrophoresis (CZE). Monolithic capillary columns were prepared in fused-silica (FS) capillaries of 150 ìm inner diameter (ID) by ionizing radiation-initiated in situ polymerization and cross-linking of diethylene glycol dimethacrylate and glycidyl methacrylate, and chemically modified with iron-protoporphyrin IX (Fe-ProP). Monolithic microcolumns were coupled online at the inlet of the separation capillary (FS capillary, 75 ìm ID x 10 cm from the inlet to the microextractor and 27 cm from microextractor to detector). Angiotensin I was released from the sorbent by a 50 mM sodium phosphate, pH 2,5:ACN 75:25 v/v solution and then analyzed by CZE with UV-absorption detection at 214 nm. The concentration limit of quantification (CLOQ) was 0.5 ng/mL. The Fe-ProP-derivatized monolithic microextractor coupled to the separation capillary exhibited a high retention capacity for peptide angiotensin I and showed as much as 10000-fold improvement in concentration sensitivity.