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Peptide Purity Levels: Research-Grade Comparison
Different purity specifications serve different experimental needs. The table below maps peptide purity levels to typical impurity content, appropriate research applications, and practical limitations you should expect at each grade. 70–85% (Crude) 15–30% dele
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- Different purity specifications serve different experimental needs. The table below maps peptide purity levels to typical impurity content, appropriate research applications, and practical limitations you should expect at each grade.
- 70–85% (Crude)
- 15–30% deletion peptides, 2–5% salts, residual reagents
- Preliminary screening, non-quantitative assays, immunogen preparation
- Unpredictable batch-to-batch variation, unsuitable for dose-response studies
- Acceptable only for applications where peptide identity matters more than precise concentration. Avoid for any quantitative work
- 85–95%
- 5–10% deletion peptides, 1–3% dimers/aggregates, trace TFA
- Cell culture studies, non-competitive binding assays, in vivo pilot studies
- Impurities may interfere with receptor selectivity, concentration accuracy ±5–8%
- Standard commercial grade. Sufficient for exploratory work but requires careful controls and should not be used for IC50 or EC50 determination
- 95–98%
- 2–4% deletion peptides, <1% aggregates, <0.5% salts
- Competitive binding assays, dose-response studies, metabolic flux experiments
- Deletion peptides near target mass may co-elute and contribute to apparent activity
- Minimum recommended purity for quantitative receptor pharmacology. Batch-to-batch consistency becomes critical at this level
- 98–99%
- <1.5% deletion peptides, <0.3% aggregates, minimal salts
- High-precision dose-response, IC50/EC50 determination, crystallography
- Cost increases significantly, synthesis time longer due to multiple purification passes
- Required for studies where peptide stoichiometry directly affects calculated parameters. Small impurity fractions still detectable by MS
- ≥99% (Ultra-Pure)
- <0.5% total impurities, typically single deletion peptide species
- NMR structure determination, reference standards, regulatory submissions
- 4–6× cost of 95% grade, availability limited to peptides <30 amino acids
- Necessary only when impurity identity must be fully characterized or when peptide serves as a calibration standard. Overkill for most research applications