Research Information System
SENSORS AND ACTUATORS B-CHEMICAL, vol.208, pp.164-172, 2015 (SCI-Expanded)
A solid phase extraction (SPE) based monolithic disc integrated microchip was developed for purposes of detection or qualitative determination of basic catecholamines: epinephrine (E), norepinephrine (NE) and dopamine (DA). The method is based on the use of a weak cation-exchange porous monolith, prepared in situ in the chamber of the boro-float microchip via photoinitiated polymerization to form desired poly(methacrylic acid-ethylene glycol dimethacrylate) [poly(MA-EGDMA)] monolithic phase which served as a SPE matrix. A surface area of 29.45 m(2)g(-1) was measured for the monolithic SPE material, obtained by using BET (Brunauer-Emmett-Teller) method. Adsorption of the catecholamines on SPE monolith was achieved using 20 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), buffered at pH 7 to protonate analytes while desorption was performed with 100 mM phosphate, buffered at pH 3 to protonate the carboxylate groups of the monolithic phase which releases the analytes. The effects of the two sample injection methods (electrokinetic and pressure) on adsorption using cation-exchange based monolithic disc were examined. The detection of catecholamines was achieved on the separation channel of the microchip during the elution step via a laser-induced native fluorescence (LINF) measurement without any expensive and time consuming labelling processes. Different buffer combinations were used to establish a good correlation between native fluorescence intensity and high elution ratio of the catecholamines. The applicability of this approach to standard catecholamine solutions promises a potential for future investigations such as catecholamine separation and detection in actual samples. (C) 2014 Elsevier B.V. All rights reserved.