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Impurity Profiling

Identification and Quantification of Peptide Impurities

Types of Peptide Impurities

Impurity Origin HPLC Profile
Deletion sequences Incomplete coupling Earlier eluting
Truncated peptides Failed deprotection Earlier eluting
Insertion sequences Double coupling Later eluting
D-isomers Racemization during activation Co-eluting or shoulder
β-Asp peptides Aspartimide formation Earlier or later
Impurity Origin Detection
Oxidation products Air/stress MS +16 Da
Deamidation pH/temperature MS +1 Da
Aggregates Concentration/temperature SEC-HPLC
Hydrolysis products Acidic conditions MS fragment

Impurity Profiling by HPLC-MS

flowchart LR
    A[Sample] --> B[HPLC Separation];
    B --> C[UV Detection<br/>214 nm];
    C --> D[Mass Detection<br/>ESI-MS];
    D --> E[Identify Each<br/>Peak by Mass];
    E --> F[Quantify Impurities<br/>Area %];
    F --> G[Report Profile];

What Are Acceptable Single Impurity Limits?

Impurity Level Research Grade GMP Grade
Any single impurity ≤2.0% ≤0.5–1.0%
Total impurities ≤5.0% ≤2.0%
Unknown impurity ≤1.0% ≤0.2%

Identification Confidence

Confidence Level Evidence Required
Tentative Retention time + mass match
Confirmed Retention time + MS/MS fragmentation
Definitive Co-elution with reference standard
  • Identification and Quantification of Peptide Impurities — Review the section above for key parameters, methods, and quality criteria.
  • Types of Peptide Impurities — Review the section above for key parameters, methods, and quality criteria.
  • Impurity Profiling by HPLC-MS — Review the section above for key parameters, methods, and quality criteria.
  • What Are Acceptable Single Impurity Limits? — See the section for detailed parameters and specifications.

Key Takeaways

  • Identification and Quantification of Peptide Impurities — Review the section above for key parameters, methods, and quality criteria.
  • Types of Peptide Impurities — Review the section above for key parameters, methods, and quality criteria.
  • Impurity Profiling by HPLC-MS — Review the section above for key parameters, methods, and quality criteria.
  • What Are Acceptable Single Impurity Limits? — See the section above for detailed parameters and specifications.

🔗 Related: HPLC Analysis | LC-MS Testing | Purity Analysis | Peptide Quality Control Guide