An equivalent length model of microdialysis sampling

Sheng Tong, Fan Yuan

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


One of the critical issues in microdialysis sampling is how to predict the extraction fraction (Ed), based on transport properties of analytes in both tissues and probes. A one-dimensional (1-D) model has been used widely in previous studies to predict Ed at the steady state. However, this model is valid only for long probes. To this end, an equivalent length (EL) model was developed for probes with any length used in experiments. The key idea in the model was to replace the probe length (L) in the 1-D model with an equivalent length (LE) when calculating transport resistance in surrounding tissues. The length difference, (LE-L), was assumed to be proportional to the penetration depth of analytes (Γ). The proportionality constant (λ) was determined through minimizing the errors in predicted Ed. We found that, the EL model could accurately predict Ed when λ=0.369. The maximum error in EL model predictions was <6%, for model constants varying in the same ranges as those in microdialysis experiments. This error was one order of magnitude smaller than that in 1-D model predictions.

Original languageEnglish
Pages (from-to)269-278
Number of pages10
JournalJournal of Pharmaceutical and Biomedical Analysis
Issue number2
StatePublished - Apr 15 2002

Bibliographical note

Funding Information:
The work is supported in part by a grant from the National Institutes of Health (CA 87630).


  • Drug delivery
  • Extraction fraction
  • Microdialysis

ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmaceutical Science
  • Drug Discovery
  • Spectroscopy
  • Clinical Biochemistry


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