Providing Enhanced Migration Time Reproducibility with a High-Voltage-Compatible Flow Sensor for Capillary Electrophoresis

Kehl, Florian; Drevinskas, Tomas; Creamer, Jessica S.; DeMartino, Andrew J; Willis, Peter

doi:10.1021/acs.analchem.2c00038

Cited by 10 publications

(6 citation statements)

References 42 publications

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“…To allow for the mechanical mounting and rotation of the system in these experiments, another instrument in development with a shorter capillary ( L tot 50 cm, L eff 40 cm) and a 10 kV separation voltage was used. Peak migration times were adjusted based on any parasitic siphoning flows, similar to the independent reservoir rotation tests, via active flow monitoring [26], and temperature‐induced baseline fluctuations in the data were compensated using a previously published procedure [27]. Overall, these results demonstrate that the reservoirs are not affected by the orientation of the gravity vector, and because they are single‐phase, would behave suitably under microgravity conditions.…”

Section: Resultsmentioning

confidence: 99%

A gravity‐independent single‐phase electrode reservoir for capillary electrophoresis applications

et al. 2023

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Capillary electrophoresis (CE) holds great promise as an in situ analytical technique for a variety of applications. However, typical instrumentation operates with open reservoirs (e.g., vials) to accommodate reagents and samples, which is problematic for automated instruments designed for space or underwater applications that may be operated in various orientations. Microgravity conditions add an additional challenge due to the unpredictable position of the headspace (air layer above the liquid) in any two‐phase reservoir. One potential solution for these applications is to use a headspace‐free, flow‐through reservoir design that is sealed and connected to the necessary reagents and samples. Here, we demonstrate a flow‐through high‐voltage (HV) reservoir for CE that is compatible with automated in situ exploration needs, and which can be electrically isolated from its source fluidics (in order to prevent unwanted leakage current). We also demonstrate how the overall system can be rationally designed based on the operational parameters for CE to prevent electrolysis products generated at the electrode from entering the capillary and interfering with the CE separation. A reservoir was demonstrated with a 19 mm long, 1.8 mm inner diameter channel connecting the separation capillary and the HV electrode. Tests of these reservoirs integrated into a CE system show reproducible CE system operation with a variety of background electrolytes at voltages up to 25 kV. Rotation of the reservoirs, and the system, showed that their performance was independent of the direction of the gravity vector.

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Section: Resultsmentioning

confidence: 99%

A gravity‐independent single‐phase electrode reservoir for capillary electrophoresis applications

et al. 2023

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“…However, EOF can still impact both kinds of electropherograms. Therefore, the quest for EOF monitors, such as the thermal marks [26,27] or flow sensors [10], is important. Of course, having a stable EOF would be even better.…”

Section: Discussionmentioning

confidence: 99%

“…In a recent paper, Kehl et al. realized that a charge‐based scale is more robust than the time‐based scale of a regular electropherogram [10]. The basic idea is to use the electrophoretic current as a normalization factor allowing electropherograms performed at different voltages and, consequently, different currents.…”

Section: Introductionmentioning

confidence: 99%

Qualitative and quantitative aspects of time‐, charge‐, and mobility‐based electropherograms

2022

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The migration process in capillary electrophoresis is obtained by using a highvoltage power supply, and the basic idea is to keep the control on the migration velocity of the analytes by controlling either the applied voltage or current. The effectiveness of this control has impact on the resulting electropherogram and, thus, in the identification and quantification of the analytes. Although the usual electropherogram is the record of the detector signal as a function of time, other two domains should be considered: charge and mobility. Both mathematical modeling and experimental results were used to evaluate the two different approaches for controlling the electrophoretic migration and the resulting time-, charge-, and mobility-based electropherograms. The main conclusions are (1) the current-controlled mode is superior to the voltage-controlled mode; (2) when the first mode cannot be implemented, the electrophoretic current should be monitored to improve the identification and quantification procedures; and (3) the consistent monitoring of the electrophoretic current allows the implementation of the charge-based electropherogram and the mobility spectrum. The first one is advantageous because the peak position is more reproducible, and the peak area is more resistant to change than the ones from the time-based electropherogram. The mobility spectrum has the additional advantage of being more informative about the mobility of the analytes. Although peak area is less robust, the spectrum may also be used for quantitation when the number of plates is greater than 10 3 . K E Y W O R D Scapacitively coupled contactless conductivity detection, charge-based electropherogram, mobility spectrum, peak area INTRODUCTIONAn experiment in capillary electrophoresis (CE) can be described, in a few words, as to introduce a sample plug at the inlet of a capillary already filled with a background Abbreviations: C 4 D, capacitively coupled contactless conductivity detection; HV, high voltage. electrolyte (BGE), high voltage (HV) is applied to the electrodes, and the detector signal is monitored as a function of time. This simple procedure describes how capillary zone electrophoresis (CZE) and a few other CE techniques are performed. All of them share the concept of electropherogram: the record of the detector signal as a function of time. An electropherogram is interpreted similarly to a chromatogram, which was opportune in the early days of CE,

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“…These include the reagent and waste unit, the fluidic selection and distribution unit, the CE unit, and the pneumatic unit. The CE unit utilizes components that have been previously reported, such as rotor-stator injection valves, a high voltage compatible flow sensor, two gravity-independent high-voltage reservoirs that can operate at any orientation, and six bubble traps.…”

Section: Methodsmentioning

confidence: 99%

Submersible Capillary Electrophoresis Analyzer: A Proof-of-Concept Demonstration of an In Situ Instrument for Future Missions to Ocean Worlds

et al. 2023

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We report here the first fully automated capillary electrophoresis (CE) system that can be operated underwater. The system performs sample acquisition and analysis by coupling CE to contactless conductivity detection. Using 5 M acetic acid as the background electrolyte (BGE), inorganic cations and amino acids at concentrations as low as 5.2 μM can be separated and identified. This technology could be augmented to include a variety of other detection modes. This system serves as an early prototype for potential future underwater explorers on ocean worlds of the outer solar system such as Europa or Enceladus. This work documents the first step in the development of this general-purpose technology platform.

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Providing Enhanced Migration Time Reproducibility with a High-Voltage-Compatible Flow Sensor for Capillary Electrophoresis

Cited by 10 publications

References 42 publications

A gravity‐independent single‐phase electrode reservoir for capillary electrophoresis applications

A gravity‐independent single‐phase electrode reservoir for capillary electrophoresis applications

Qualitative and quantitative aspects of time‐, charge‐, and mobility‐based electropherograms

Submersible Capillary Electrophoresis Analyzer: A Proof-of-Concept Demonstration of an In Situ Instrument for Future Missions to Ocean Worlds

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