Capillary electrophoresis of neurotransmitters with amperometric detection at melanin-type polymer-modified carbon electrodes

Chicharro, Manuel; Sánchez, A.S. Salinas; Zapardiel, Antonio; Rubianes, María D.; Rivas, Gustavo A.

doi:10.1016/j.aca.2004.07.039

Cited by 63 publications

(24 citation statements)

References 24 publications

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“…At the modified electrode, the resolution (R), which was calculated following a previously described equation [31], was found to be much better than that of the bare one. The R value between the DA and the NE at the modified electrode was found to be 2.2, whereas at the bare one, it was [17,18,27]. The relative flat baseline and the low noise levels (peak-to-peak noise levels of 25-30 pA were observed at a modified electrode) at the experimental field strength indicated an effective isolation from the high field strength when the modified electrode was used.…”

Section: Simultaneous Analysis Of Da Ne L-dopamentioning

confidence: 74%

“…Therefore, the detection and separation of DA has been given tremendous consideration in a biochemical research, especially when there is a need for a sensitive, selective, and fast method for the direct detection of DA. More recently, the determination of neurotransmitters and DNA fragments on a Pt-electrode patterned on a glass chip [23], enzymecatalyzed amperometric oxidation of neurotransmitters on a gold electrode [24], the chiral on-chip separation of neurotransmitters [25], acetylcholine and other neurotransmitters on a sealed electrode into the capillary [26], and neurotransmitters on a polymer modified carbon disk electrode [27] have been reported in the CE-EC electrophoresis system.…”

Section: Introductionmentioning

confidence: 99%

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Microchip capillary electrophoresis with a cellulose-DNA-modified screen-printed electrode for the analysis of neurotransmitters

et al. 2005

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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 mM 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/microM with detection limits of 0.032, 0.93, 1.13, 0.31, and 0.62 microM, respectively. The applicability of this microsystem to real sample analysis was demonstrated.

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Section: Simultaneous Analysis Of Da Ne L-dopamentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Microchip capillary electrophoresis with a cellulose-DNA-modified screen-printed electrode for the analysis of neurotransmitters

et al. 2005

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“…Table 1 summarizes the regression equation, correlation coefficient and detection limits [30]. The results demonstrate that the method of alternate running buffers CZE was suitable for the detection of the six analytes, allowing a reproducible and more sensitive quantification of mixtures containing the six analytes.…”

Section: Repeatability Linearity and Detection Limitsmentioning

confidence: 92%

Simultaneous determination of dihydroxybenzene and phenylenediamine positional isomers using capillary zone electrophoresis coupled with amperometric detection

Dong¹,

Chi²,

Yang³

et al. 2009

J of Separation Science

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In general capillary zone electrophoresis (CZE) separation models, o-, m-, and p-phenylenediamine isomers can be separated in a weak acidic running buffer for their pK(a) values being 4.52, 5.64, 6.04, respectively, while o-, m-, and p-dihydroxybenzene isomers can be separated in a weak basic buffer for their pK(a) values being 9.40, 9.40 and 10.04, respectively. So, it is hard to find a suitable running buffer at a fixed pH in normal CZE for simultaneous separation of these two groups of positional isomers. In this paper, a novel method based on alternately running two different pH buffers in CZE coupled with amperometric detection (CZE-AD) was designed to simultaneously determine these two groups of positional isomers. It is found that when two different pH running buffers were employed alternately under appropriate order and time, the six analytes could be separated perfectly in less than 20 min and the detection limits were as low as 10(-7) mol/L. Furthermore, the effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CZE-AD were investigated. Experimental results demonstrated that the introduced method was practical to simultaneously determine two groups of positional isomers with different pK(a) and had some advantages of high sensitivity, good repeatability and small sample requirement.

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“…The authors also constructed a new EC cell including a Nafion decoupler for CE-ECD. A melanin-type polymermodified glassy-carbon electrode and graphite-carbon electrodes showed sensitivities 3-5 times higher than bare-carbon electrodes and LODs at sub-micromolar levels in neurotransmitter CE-EC [21], because of more efficient electron transfer and excellent permselectivity of the melanin polymers.…”

Section: Electrode Material-besidesmentioning

confidence: 99%

Electrochemical and optical detectors for capillary and chip separations

Weber

2007

TrAC Trends in Analytical Chemistry

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In separations in capillaries or on chips, the most predominant detectors outside of the field of proteomics are electrochemical (EC) and optical. These detectors operate in the μM to pM range on nL peak volumes with ms time resolution. The driving forces for improvement are different for the two classes of detectors.With EC detectors, there are two limitations that the field is trying to overcome. One is the everpresent surface of the electrode which, while often advantageous for its catalytic or adsorptive properties, is also frequently responsible for changes in sensitivity over time. The other is the decoupling of the electrical systems that operate electrokinetic separations from the system operating the detector.With optical detectors, there are similarly a small number of important limitations. One is the need to bring the portability (size, weight and power requirements) of the detection system into the range of EC detectors. The other is broadening and simplifying the applications of fluorescence detection, as it almost always involves derivatization.Limitations aside, the ability to make detector electrodes and focused laser beams of the order of 1 μm in size, and the rapid time response of both detectors has vaulted capillary and chip separations to the forefront of small sample, fast, low mass-detection limit analysis.

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Capillary electrophoresis of neurotransmitters with amperometric detection at melanin-type polymer-modified carbon electrodes

Cited by 63 publications

References 24 publications

Microchip capillary electrophoresis with a cellulose-DNA-modified screen-printed electrode for the analysis of neurotransmitters

Microchip capillary electrophoresis with a cellulose-DNA-modified screen-printed electrode for the analysis of neurotransmitters

Simultaneous determination of dihydroxybenzene and phenylenediamine positional isomers using capillary zone electrophoresis coupled with amperometric detection

Electrochemical and optical detectors for capillary and chip separations

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