Measurement of iohexol by capillary electrophoresis: minimizing practical problems encountered

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Biomarker Measurement

Background:

• Iohexol is recognized as an accurate marker for glomerular filtration rate (GFR) measurement.
• Accurate GFR assessment is crucial for managing kidney disease.
• Existing methods require optimization for clinical trial reproducibility.

Purpose of the Study:

• To establish a reproducible capillary electrophoresis (CE) assay for iohexol measurement.
• To validate the assay for use in clinical trials.
• To identify and mitigate factors causing laboratory variation.

Main Methods:

• Optimization of CE separation with an internal standard.
• Evaluation of deproteinization methods for serum samples.
• Selection of optimal matrix for standard dilutions.
• Implementation of quality control materials for run-to-run consistency.

Main Results:

• The optimized CE assay for iohexol demonstrated robustness over 9 months and 860 runs.
• The assay achieved a coefficient of variation (CV) of 4.3% at 80 mg/L with a run time of 5.25 minutes.
• Consumable costs were below A$0.25 per test, excluding instrument costs.
• GFR calculated from plasma clearance showed a reproducibility of 5.47%.

Conclusions:

• A precise and reproducible capillary electrophoresis assay for iohexol has been successfully developed.
• The assay is suitable for clinical trials due to its robustness, low cost, and minimal variability.
• This method provides a reliable tool for accurate GFR assessment.