Determination of metal cations in microchip electrophoresis using on-chip complexation and sample stacking

Kutter, Jörg Peter; Ramsey, Roswitha S.; Jacobson, Stephen C.; Ramsey, J. Michael

doi:10.1002/(sici)1520-667x(1998)10:4<313::aid-mcs1>3.0.co;2-j

Cited by 66 publications

(14 citation statements)

References 30 publications

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“…FASS techniques have been implemented on-chip as a preparation method for mass spectrometry [56] and in combination with CE [50]. Fieldamplified injection, a similar application of electrokinetic stacking phenomena, has been reported on chip as well [57,58]. Figure 8 shows three CE separations of a single cation sample containing 100 mM K 1 .…”

Section: Field-amplified Sample Stackingmentioning

confidence: 99%

A microchip electrophoresis system with integrated in-plane electrodes for contactless conductivity detection

2002

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We present a new approach for contactless conductivity detection for microchip-based capillary electrophoresis (CE). The detector integrates easily with well-known microfabrication techniques for glass-based microfluidic devices. Platinum electrodes are structured in recesses in-plane with the microchannel network after glass etching, which allows precise positioning and batch fabrication of the electrodes. A thin glass wall of 10-15 microm separates the electrodes and the buffer electrolyte in the separation channel to achieve the electrical insulation necessary for contactless operation. The effective separation length is 34 mm, with a channel width of 50 microm and depth of 12 microm. Microchip CE devices with conductivity detection were characterized in terms of sensitivity and linearity of response, and were tested using samples containing up to three small cations. The limit of detection for K+ (18 microM) is good, though an order of magnitude higher than for comparable capillary-based systems and one recently reported example of contactless conductivity on chip. However, an integrated field-amplified stacking step could be employed prior to CE to preconcentrate the sample ions by a factor of four.

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Section: Field-amplified Sample Stackingmentioning

confidence: 99%

A microchip electrophoresis system with integrated in-plane electrodes for contactless conductivity detection

2002

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“…FAS has been applied to microchip-based analysis by Jacobson and Ramsey [24] and Kutter et al [25] using gated injection into the separation channel to form long injection plugs for large anion and metal cation analysis, respectively. Li et al [26] used stacking of long proteincontaining sample zones for sample preconcentration prior to injection into a mass spectrometer, with enrichment factors of up to 50-fold.…”

Section: Introductionmentioning

confidence: 99%

Sample preconcentration by field amplification stacking for microchip-based capillary electrophoresis

2001

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A microchip structure for field amplification stacking (FAS) was developed, which allowed the formation of comparatively long, volumetrically defined sample plugs with a minimal electrophoretic bias. Up to 20-fold signal gains were achieved by injection and separation of 400 microm long plugs in a 7.5 cm long channel. We studied fluidic effects arising when solutions with mismatched ionic strengths are electrokinetically handled on microchips. In particular, the generation of pressure-driven Poiseuille flow effects in the capillary system due to different electroosmotic flow velocities in adjacent solution zones could clearly be observed by video imaging. The formation of a sample plug, stacking of the analyte and subsequent release into the separation column showed that careful control of electric fields in the side channels of the injection element is essential. To further improve the signal gain, a new chip layout was developed for full-column stacking with subsequent sample matrix removal by polarity switching. The design features a coupled-column structure with separate stacking and capillary electrophoresis (CE) channels, showing signal enhancements of up to 65-fold for a 69 mm long stacking channel.

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“…Similarly, detection sensitivity is also an important issue in microchip electrophoresis although fluorescence detectors are usually used in this case. Jacobson and Ramsey [8] and Kutter et al [9] reported the on-line concentration of dansyl amino acids and inorganic ions by stacking in microchip electrophoresis and obtained the maximum of 31-fold enhancement in the detection sensitivity for the fluorescence detection of didansyl-lysine. Recently, Palmer et al [10] also reported an on-line concentration of neutral analytes on a microchip by stacking.…”

Section: Introductionmentioning

confidence: 99%

Sweeping on a microchip: Concentration profiles of the focused zone in micellar electrokinetic chromatography

et al. 2001

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On-line sample concentration by sweeping was investigated in microchip micellar electrokinetic chromatography (MEKC), By changing the distance between the injection cross and the detection points, the profile of the concentration process and the diffusion process in sweeping was elucidated. Rhodamine B injected for 4 s was best concentrated by sweeping at 9.4 mm from the injection cross and the enhancement factor was 450. At the longer distance from this point the peak of Rhodamine B was broadened and diluted by diffusion. The diffusion constant of Rhodamine B calculated from the experiment was 5.7 x 10(-6) cm2s(-1). The mixture of rhodamine B, sulforhodamine B, and cresyl fast violet was concentrated by sweeping and separated by MEKC at the same time.

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Determination of metal cations in microchip electrophoresis using on-chip complexation and sample stacking

Cited by 66 publications

References 30 publications

A microchip electrophoresis system with integrated in-plane electrodes for contactless conductivity detection

A microchip electrophoresis system with integrated in-plane electrodes for contactless conductivity detection

Sample preconcentration by field amplification stacking for microchip-based capillary electrophoresis

Sweeping on a microchip: Concentration profiles of the focused zone in micellar electrokinetic chromatography

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