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Microchip capillary electrophoresis with a cellulose‐DNA‐modified screen‐printed electrode for the analysis of neurotransmitters
Author(s) -
Johirul Muhammad,
Shiddiky Alam,
Kim RogEun,
Shim YoonBo
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.200410438
Subject(s) - capillary electrophoresis , electrode , detection limit , amperometry , chromatography , ascorbic acid , chemistry , analytical chemistry (journal) , electrophoresis , cellulose , electrochemistry , biochemistry , food science
A microfluidic chip based on capillary electrophoresis coupled with a cellulose‐single‐stranded DNA (cellulose‐ssDNA) modified electrode was used for the simultaneous analysis of dopamine (DA), norepinephrine (NE), 3,4‐dihydroxy‐ L ‐phenylalanine ( L ‐DOPA), 3,4‐dihydroxyphenylacetic acid (DOPAC), and ascorbic acid (AA). The modification of the electrode improved the electrophoretic analysis performance by lowering the detection potential and enhancing the signal‐to‐noise characteristic without surface poisoning of the electrode. The sensitivity of the modified electrode was about 12 times higher than those of the bare ones. The test compounds were separated using a 62 mm long separation channel at the separation field strength of +200 V/cm within 220 s in a 10 m M phosphate buffer (pH 7.4). The most favorable potential for the amperometric detection was 0.7 V ( vs . Ag/AgCl). A reproducible response (relative standard deviation of 1.3, 1.3, 2.1, 3.1, 3.4% for DA, NE, L ‐DOPA, DOPAC, and AA, respectively, for n = 9) for repetitive sample injections reflected the negligible electrode fouling at the cellulose‐ssDNA modified electrode. Square‐wave voltammetric analyses reflected the sensitivities of the modified electrode for DA, NE, L ‐DOPA, DOPAC, and AA which were 1.78, 0.82, 0.69, 2.45, and 1.23 nC/µ M with detection limits of 0.032, 0.93, 1.13, 0.31, and 0.62 µ M , respectively. The applicability of this microsystem to real sample analysis was demonstrated.