Variability of microchip capillary electrophoresis with conductivity detection

Area of Science:

• Analytical Chemistry
• Microfluidics
• Separation Science

Background:

• Microfluidic capillary electrophoresis (CE) offers potential for portable analytical devices.
• Reliable identification and quantification require understanding and mitigating analytical technique irreproducibility.

Purpose of the Study:

• To develop a protocol for mitigating baseline drift in microfluidic CE.
• To assess measurement variability across multiple microchips and substrate batches.
• To identify sources of irreproducibility in microfluidic CE measurements.

Main Methods:

• A pre-analysis conditioning protocol was implemented.
• Measurement variability was assessed using 24 microchips from six glass substrate batches.
• Retention time and peak area reproducibility were quantified using relative standard deviation (RSD).

Main Results:

• The developed protocol effectively addressed baseline drift issues.
• Acceptable RSD percentages were observed for retention time measurements.
• Significant variability (up to ~50%) was found in peak area measurements across microchips.
• Variability was not linked to substrate batch but potentially to voltage fluctuations or microchannel quality.

Conclusions:

• A protocol for baseline drift in microfluidic CE was successfully developed.
• While retention times are reproducible, peak area quantification remains a challenge due to microchip variability.
• Further investigation into factors like voltage stability and microchannel uniformity is needed for improved microfluidic CE device reliability.