LC-MS Testing¶
Identity Confirmation by Mass Spectrometry¶
Principle¶
LC-MS combines HPLC separation with mass detection. The peptide's molecular weight is determined from the mass-to-charge (m/z) ratios of its multiply charged ions.
Method¶
- HPLC separates components
- ESI ionizes eluting peptides
- Mass analyzer measures m/z
- Software deconvolutes charge states
Interpretation¶
Spectra Features¶
- Multiple charge states: [M+H]⁺, [M+2H]²⁺, [M+3H]³⁺, etc.
- Deconvolution: Software calculates monoisotopic or average mass
- Adducts: Na⁺, K⁺, TFA adducts may appear (+22, +38, +113 Da)
Expected Result¶
- Calculated mass matches theoretical mass within ±1 Da
What LC-MS Detects¶
| Feature | Detection |
|---|---|
| Correct mass → identity confirmed | ✅ Good |
| Mass off by ~1 AA mass | Deletion sequence |
| Mass matches but early elution | Likely D-isomer |
| Extra mass peaks | Impurities or adducts |
- Identity Confirmation by Mass Spectrometry — Review the section above for key parameters, methods, and quality criteria.
- What LC-MS Detects — See the section for detailed parameters and specifications.
Key Takeaways¶
- Identity Confirmation by Mass Spectrometry — Review the section above for key parameters, methods, and quality criteria.
- Interpretation — Review the section above for key parameters, methods, and quality criteria.
- What LC-MS Detects — See the section above for detailed parameters and specifications.
🔗 Related: LC-MS System | Mass Confirmation | HPLC Analysis | What Is a Research Peptide