An integrated solid-phase extraction system for sub-picomolar detection.
A microchip structure etched on a glass substrate for packed column solid-phase extraction (SPE) and capillary electrochromatography (CEC) is described. A 200 microm long, octadecylsilane (ODS) packed column was secured using two different approaches: solvent lock or polymer entrapment. The former method was utilized for SPE while the latter approach was applied for CEC. In SPE, the ODS packed chamber gave a detection limit of 70 fM for a nonpolar BODIPY (493/503) dye when concentrated for 3 min at an electroosmotic flow rate of 4.14 nL/min, compared to 30 pM for this detector without the SPE step. SPE beds showed reproducible, linear calibration curves (R(2) = 0.9989) between 1 and 100 pM BODIPY at fixed preconcentration times. Breakthrough curves for the 330 pL (ODS-packed) bed indicated a capacity for BODIPY dye of 8.1 x 10(-14) mmol, or 0.25 mmol dye per liter of bed. The ODS-chamber could also be used to analyze dilute amino acid and peptide solutions. In the CEC format, two neutral dyes (BODIPY and acridine orange) were baseline-separated in an isocratic run with a theoretical plate count of 84 (420 000 plates/m) and a reduced plate height of about 1. A labeled peptide was also analyzed by CEC, using the acidic eluent (84% acetonitrile, and 26% aqueous trifluoroacetic acid (0.05%)) preferred for peptide separations on ODS-coated silica particles.
Jemere
Abebaw Belay
AB
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Oleschuk
Richard D
RD
Ouchen
Fahima
F
Fajuyigbe
Festus
F
Harrison
D Jed
DJ
D000165:Acridine Orange / Q000302:isolation & purification; D000596:Amino Acids / Q000302:isolation & purification; D001896:Boron Compounds / Q000302:isolation & purification; D005591:Chemical Fractionation / Q000379:methods; D019075:Electrophoresis, Capillary / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D008904:Miniaturization
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D000596:Amino Acids; D001896:Boron Compounds; D000165:Acridine Orange