Integrated internal standards: A sample prep-free method for better precision in microchip CE

Area of Science:

• Analytical Chemistry
• Microfluidics
• Point-of-Care Diagnostics

Background:

• Disposable microchip capillary electrophoresis (CE) systems require prefilled, single-use chips for untrained operators.
• Manufacturing variations in microchips can impact analyte precision.
• Integrated internal standards (ISTDs) were previously proposed to improve measurement accuracy without added cost or complexity.

Purpose of the Study:

• To evaluate the effectiveness of integrated internal standards (ISTDs) for improving potassium ion (K) quantification in a clinically relevant context.
• To assess the application of ISTDs in disposable microchip CE devices using a mock blood solution.

Main Methods:

• Utilized microchip capillary electrophoresis with integrated internal standards (cesium ions, Cs).
• Analyzed potassium ion (K) concentrations in a mock blood solution to simulate physiological samples.
• Measured migration times, calibration correlation coefficients (R²), and peak area repeatability.

Main Results:

• Integrated ISTD (Cs) improved K ion migration time repeatability from 6.97% to 0.89%.
• Linear calibration correlation coefficient (R²) for K quantification increased from 0.851 to 0.967.
• Peak area repeatability improved from 11.6-13.3% to 4.75-5.04% for K concentrations above the limit of quantification (LOQ).

Conclusions:

• Integrated internal standards (ISTDs) effectively enhance precision and accuracy in disposable microchip CE devices.
• This approach is feasible for analyzing physiological samples, demonstrating its potential for point-of-care applications.
• ISTDs offer a cost-effective solution to mitigate manufacturing variability and improve diagnostic reliability.