A simple and low‐cost electrochemiluminescence detector for capillary electrophoresis

Abstract

A simple and cost-effective electrochemiluminescence (ECL) detector for capillary electrophoresis (CE) has been developed. The detector was constructed by vertically gluing a 0.5 mL plastic sample vial onto a piece of 1.5 cm x 1 cm x 0.6 mm indium/tin oxide (ITO)-coated glass plate. End-column ECL detection was performed in a wall-jet configuration. Potential control of the ITO electrode was provided using a direct current (DC) battery. Tris(2,2'-bipyridyl)ruthenium(III) (Ru(bpy)3(3+))-based ECL reaction was used for sensitive detection of four trialkylamines (trimethylamine, triethylamine, tripropylamine, tributylamine) and two amino acids (proline, hydroxyproline). With 15 mM sodium borate (pH 9.5) plus 3.5 mM Ru(bpy)3(2+) present in the detection cell and the ITO electrode biased at 1.7 V (vs. platinum wire reference), the test analytes can be efficiently separated and sensitively detected by the developed CE-ECL system. Linearity (r > or = 0.995) over two orders of magnitude and an average number of theoretical plates of 160 000/m were generally obtained. Reproducibility on peak height and migration times (n = 42) was 3.3% and 1.2% for tripropylamine, and 2.4% and 1.5% for proline, respectively. The detection limits were in the range of 2-5 microM (1-2 fmol) for the test analytes.

A new electrochemiluminescent detection system equipped with an electrically heated carbon paste electrode for CE

“…With the postcolumn mode, there are two approaches: (i) the Ru(bpy) 3 21 is directly added into the ECL detection cell [17,27]; (ii) the Ru(bpy) 3 21 is continuously delivered by pressure to the interface of capillary and electrode in the ECL cell [21,23,24]. However, for the first approach the CE buffer solution effused from the capillary would dilute the concentration of Ru(bpy) 3 21 near the surface of the working electrode, while the second approach needs complicated equipment.…”

“…In research of CE-ECL, various working electrodes for ECL detection were investigated, such as a Pt disk electrode [23][24][25], a modified Pt disk electrode [26], glassy carbon electrode [6], and indium tin oxide electrode [27,28], etc. However, these conventional electrodes all work at room temperature and must be grinded to get a fresh surface for the reproducibility.…”

Determination of tertiary amines based on pH junctions and field amplification in capillary electrophoresis with electrochemiluminescence detection

“…Another greater concern is that band broadening usually occurs in the off-column mode, leading to a loss of resolution. To overcome these disadvantages and to minimize HV effects, CE separation with lowconductivity buffer and small inner diameter of capillaries (50 and 25 mm) has been suggested [24][25][26]. Using indium/tin oxide (ITO) working electrodes in CE-ECL systems, Chiang et al [24,25] reported LODs in the range of 1.0-5.0 mM for triethylamine (TEA), tripropylamine (TPA), and tributylamine (TBA).…”

Advances and analytical applications in chemiluminescence coupled to capillary electrophoresis

“…The method was applied to honey with only a dilution and filtration pretreatment. In addition, using the ECL detector previously proposed by Chiang et al [65], trimethylamine, an indicator of spoiling in fish, has been sensitively determined [77]. In addition, acetylcholine was detected in royal jelly by previous decomposition into trimethylamine when it was heated to its melting point [78].…”

“…A cost-effective ECL detector for CE, simpler that a preliminary design [64], was developed by Chiang et al [65]. It was constructed by vertically gluing a 0.5-mL plastic sample vial onto a piece of 1.5 cm  1 cm  0.6 mm indium/tin oxide (ITO)-coated glass plate.…”