Quantitation in capillary electrophoresis-mass spectrometry

Area of Science:

• Analytical Chemistry
• Biotechnology
• Pharmaceutical Analysis

Background:

• Capillary electrophoresis-mass spectrometry (CE-MS) is emerging as a powerful alternative to liquid chromatography-mass spectrometry (LC-MS).
• While primarily used for characterization and identification, quantitative applications of CE-MS are increasingly important in pharmaceutical and biotechnological fields.
• Achieving sensitive and reproducible quantitative results requires careful consideration of methodological aspects.

Purpose of the Study:

• To summarize and evaluate methodological aspects for sensitive and reproducible quantitative CE-MS.
• To highlight critical factors for successful quantitative CE-MS analysis.
• To provide an overview of quantitative measurements performed by CE-MS through a literature survey.

Main Methods:

• Evaluation of methodological aspects for sensitive and reproducible CE-MS.
• Addressing matrix effects on the electrospray process, similar to LC-MS.
• Focusing on the CE-MS interface, a critical component for quantitative analysis.
• Assessing linearity over multiple orders of magnitude.
• Literature survey of quantitative CE-MS applications.

Main Results:

• Linearity over more than three orders of magnitude can be achieved with CE-electrospray ionization-mass spectrometry (CE-ESI-MS).
• Matrix effects on the electrospray process must be carefully managed for quantitative CE-MS.
• The CE-MS interface requires special attention due to its complexity.
• Precision can be significantly improved (doubled) by using isotopically labeled internal standards compared to structurally related ones.
• A precision level better than 5% relative standard deviation (RSD) is achievable.

Conclusions:

• CE-MS is a viable technique for quantitative analysis in pharmaceutical and biotechnological applications.
• Optimization of the CE-MS interface and management of matrix effects are key to achieving high-quality quantitative data.
• The use of isotopically labeled internal standards enhances precision, enabling reliable quantification with CE-MS.