In-line application of electric field in capillary separation systems: Joule heating, pH and conductivity.

Talanta · 2008 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3404

Study snapshot

PublicationTalanta · 2008

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

This study concerns the technique electric field-assisted capillary liquid chromatography. In this technique, an electric field is applied over the separation capillary in order to provide an additional selectivity. In this technique, the electric field is applied in-line in the separation capillary and here the electric current is the factor limiting the magnitude of applied electric field. The influence of Joule heating and other factors on the current in such systems has been investigated. The temperature in the capillary was first measured within a standard CE set-up, as function of effect per unit of length. Then the same cooling system was applied to an in-line set-up, to replicate the conditions between the two systems, and thus the temperature. Thus Joule heating effects could then be calculated within the in-line system. It was found that for systems applying an electric field in line, the direct influence from Joule heating was only relatively small. The pH in the capillary was measured in the in-line set-up using cresol red/TRIS solutions as pH probe. Significant changes in pH were observed and the results suggested that electrolysis of water is the dominant electrode reaction in the in-line system. In summary, the observed conductivity change in in-line systems was found to be mainly due to the pH change by hydrolysis of water, but primarily not due the temperature change in the capillary column.

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AI evidence extraction

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Study typeengineering

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

The study investigated factors influencing current in electric field-assisted capillary liquid chromatography with an in-line applied electric field. Direct influence from Joule heating on current/conditions was reported to be relatively small, while significant pH changes were observed; results suggested water electrolysis as the dominant electrode reaction, and conductivity changes were mainly attributed to pH change rather than temperature change.

Outcomes measured

electric current limitation in in-line electric-field capillary systems
capillary temperature / Joule heating
pH changes in capillary (electrolysis/hydrolysis of water)
conductivity changes in capillary

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": null,
    "source": "in-line applied electric field in separation capillary (electric field-assisted capillary liquid chromatography)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "electric current limitation in in-line electric-field capillary systems",
    "capillary temperature / Joule heating",
    "pH changes in capillary (electrolysis/hydrolysis of water)",
    "conductivity changes in capillary"
  ],
  "main_findings": "The study investigated factors influencing current in electric field-assisted capillary liquid chromatography with an in-line applied electric field. Direct influence from Joule heating on current/conditions was reported to be relatively small, while significant pH changes were observed; results suggested water electrolysis as the dominant electrode reaction, and conductivity changes were mainly attributed to pH change rather than temperature change.",
  "effect_direction": "unclear",
  "limitations": [],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "electric field-assisted capillary liquid chromatography",
    "capillary separation",
    "Joule heating",
    "temperature",
    "pH",
    "conductivity",
    "electrolysis of water",
    "hydrolysis"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1016/j.talanta.2007.10.032
PubMed: 18371851

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