Peptide isoelectric point and charge heterogeneity
Capillary isoelectric focusing separates components by apparent isoelectric point. With imaging detection, icIEF can provide charge profiles to compare resolved peaks across batches, formulations or study conditions.
Request a technical assessmentResearch questions
- What is the apparent pI of the main peak and other resolved components?
- Do the acidic, main and basic peak distributions change across samples?
- Which profile changes merit follow-up structural work?
What the report can include
- Charge profiles and sample overlays with pI marker and peak annotations.
- Relative peak areas for resolved components, with integration rules and test conditions.
- An interpretation of the observed differences and limits of resolution.
How to interpret the results
Peak assignments to specific modifications such as deamidation or isomerization require supporting evidence. Resolution and detection depend on the molecule, matrix and focusing conditions. Relative peak area is interpreted within the measurement and integration method used.
Before sending samples
Provide the molecule, key modifications, known or estimated pI, sample concentration and formulation. To investigate an unusual peak, include the comparison batches or stress conditions and any relevant chromatographic or mass spectrometry observations.