Hydrophobicity-aided potentiometric detection of catecholamines, beta-agonists, and beta-blockers in a mixed-solvent capillary electrophoresis system.
A series of cationic drug-like substances with distinct basicity, hydrogen-bonding ability, and hydrophobicity, including three catecholamines, two beta-agonists, and thirteen beta-blockers, was successfully detected in a capillary electrophoresis system using an end-capillary coupled potentiometric sensor consisting of a PVC-based liquid membrane deposited directly on a 100 mum diameter copper rod. The electrophoretic separation was performed on a 72 cm x 75 microm id uncoated fused-silica capillary with an acidic background electrolyte containing phosphoric acid in a water-acetonitrile mixture, pH* 2.8. Samples were injected electrokinetically at 5.0 kV for 10 s and a running voltage of 19.5 kV was applied. Excluding the bufuralol/practolol pair, baseline separation of all substances was achieved in the developed CE system within 9 minutes. A linear relationship (R(2) 0.8752) between the sensitivity of the applied potentiometric detector and the parameter log P characterising the hydrophobicity of the analytes was demonstrated. The best observable limits of detection (LODs) were obtained for the highly hydrophobic substances, i. e. bufuralol (8.10 x 10(-8) M injected concentration, S/N = 3), propranolol, alprenolol, and clenbuterol (ca. 1.10 x 10(-7) M). In the case of hydrophilic catecholamines and carbuterol their LODs with potentiometric detection were lowered by a factor of almost one thousand, reaching a value of 6.6 x 10(-5) M.
Bazylak
Grzegorz
G
Instituto de Quimica Fisica de Materiales, Ambiente y Energia (INQUIMAE), Departamento de Quimica Inorganica, Analytica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina. gbazylak@cm.umk.pl
Monge
Maria Eugenia
ME
Everaert
Joseph
J
Nagels
Luc Joseph
LJ
D000318:Adrenergic beta-Agonists / Q000032:analysis*; D000319:Adrenergic beta-Antagonists / Q000032:analysis*; D002395:Catecholamines / Q000032:analysis*; D019075:Electrophoresis, Capillary / Q000379:methods*; D004983:Ethanolamines / Q000032:analysis*; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D011199:Potentiometry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry; D013997:Time Factors
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D002395:Catecholamines; D004983:Ethanolamines; D012997:Solvents; C100249:carbuterol