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Determination of tertiary amines based on pH junctions and field amplification in capillary electrophoresis with electrochemiluminescence detection
Author(s) -
Sreedhar Mallipattu,
Lin YangWei,
Tseng WeiLung,
Chang HuanTsung
Publication year - 2005
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/elps.200500009
Subject(s) - electrochemiluminescence , capillary electrophoresis , electrolyte , indium tin oxide , electrode , analytical chemistry (journal) , stacking , chemistry , working electrode , electrochromatography , ruthenium , materials science , inorganic chemistry , detection limit , chromatography , capillary electrochromatography , catalysis , biochemistry , organic chemistry
Abstract A stacking approach based on pH junction and field amplification has been developed for determining amines by capillary electrophoresis (CE) with electrochemiluminescence (ECL) detection. A two‐electrode configuration was employed with an indium/tin oxide‐coated glass as a working electrode and a platinum wire as a pseudoreference electrode. The ECL system also contains a flow cell (poly(dimethylsiloxane)‐aluminum oxide) that was made from a mixture of Sylgard 184 silicone elastomer, a curing agent, and aluminum oxide. In order to improve the sensitivity of the present CE‐ECL system using tris(2,2'‐bipyridyl) ruthenium(II) (Ru(bpy) 3 2+ ), a stacking approach based on pH junctions and field amplification has been tested for the analysis of triethylamine (TEA), tripropylamine (TPA), and tributylamine (TBA). Once amines (cations) prepared in citric acid solution (pH < 4.0) migrate towards the background electrolyte (15 m M sodium borate at pH 8.0), they slow down and are stacked at the boundary as a result of deprotonation and decreases in the electric field. By applying hydrodynamic injection of the sample for 60 s, this method provides the concentration limits of detection (signal‐to‐noise ratio = 3) of 24, 20, and 32 n M for TEA, TPA, and TBA, respectively. The results indicate that the stacking CE‐ECL system is better than CE‐ECL systems using a two‐electrode configuration and comparable to those using a three‐electrode configuration. The potential applicability of the new and low‐cost CE‐ECL system has been demonstrated by the determination of 1.0 µ M lidocaine, a local anesthetic drug, in urine without any tedious sample preparation.