Peptide purification is critical for achieving the high purity required for research and pharmaceutical applications. After synthesis, crude peptides contain deletion sequences, truncated products, and racemized impurities. This guide covers the three primary chromatographic methods used for peptide purification.
Method Separation Basis Best For Typical Purity Achieved Reverse-phase HPLC (RP-HPLC) Hydrophobicity Most peptides >98% Ion exchange (IEX) Charge Charged peptides, desalting >95% Size exclusion (SEC) Molecular size Aggregates, removal of small molecules >95% Affinity chromatography Specific binding Modified peptides, tagged peptides >99%
RP-HPLC is the most widely used method for peptide purification due to its versatility, resolution, and compatibility with mass spectrometry.
Peptides are separated based on hydrophobicity using a non-polar stationary phase (C18 or C8) and a polar mobile phase (water/acetonitrile gradient with TFA or formic acid).
Phase Particle Size Pore Size Application C18 (ODS) 3–5 µm 100–300 Å General purpose, most peptides C8 3–5 µm 100–300 Å Hydrophobic peptides C4 3–5 µm 300 Å Large peptides, proteins Phenyl 3–5 µm 100–300 Å Aromatic-rich peptides Biphenyl 3–5 µm 100–300 Å Enhanced π-π interactions
Component Role Typical Concentration Water (HPLC grade) Weak solvent 0–100% (gradient) Acetonitrile (ACN) Strong solvent 0–100% (gradient) Trifluoroacetic acid (TFA) Ion-pairing agent, pH modifier 0.05–0.1% Formic acid Alternative ion-pairing agent 0.1% Ammonium formate LC-MS compatible 10–50 mM
Time (min) %A (Water + 0.1% TFA) %B (ACN + 0.1% TFA) Purpose 0 95 5 Equilibration 5 95 5 Initial hold 60 5 95 Linear gradient 65 5 95 Column wash 70 95 5 Re-equilibration
Scale Column Dimensions Loading Capacity Analytical 4.6 × 150 mm 1–10 mg Semi-prep 10 × 150 mm 10–100 mg Preparative 21.2 × 150 mm 100–500 mg Production 50 × 150 mm 500 mg–5 g
High resolution and selectivity
Compatible with mass spectrometry
Wide range of column options
Scalable from mg to kg
Automation-friendly
TFA may cause problems for some applications (HFBA alternative)
Not ideal for very hydrophilic peptides (no retention)
Solvent waste disposal requirements
Column cost and lifetime considerations
Separates peptides based on net surface charge using charged stationary phases. Peptides bind to the column at low ionic strength and elute with increasing salt concentration or pH change.
Type Resin Charge Binds Elution Cation exchange (CEX) Negative (sulfonate) Positively charged peptides ↑ pH or ↑ [NaCl] Anion exchange (AEX) Positive (quaternary amine) Negatively charged peptides ↓ pH or ↑ [NaCl]
Resin Type Particle Size Application SP Sepharose Strong CEX 90 µm General peptides CM Sepharose Weak CEX 90 µm pH-dependent separation Q Sepharose Strong AEX 90 µm General peptides DEAE Sepharose Weak AEX 90 µm pH-dependent separation
Equilibrate column with low-salt buffer (20 mM phosphate, pH 7.0)Load sample dissolved in equilibration bufferWash to remove unbound materialElute with linear salt gradient (0–1 M NaCl) or step gradientCollect fractions and analyze by SDS-PAGE or HPLCDesalt pooled fractions (desalting column or dialysis)
High loading capacity
Non-denaturing conditions
Scalable to large volumes
Good for removing charge variants
Complementary to RP-HPLC
Lower resolution than RP-HPLC for similar-charge peptides
Requires buffer exchange after purification
Salt removal necessary for downstream applications
Limited to peptides with net charge
Separates peptides by hydrodynamic size (molecular radius). Large molecules elute first (excluded from pores); small molecules elute later (enter pores).
Resin Fractionation Range Application Superdex Peptide 100–7,000 Da Small peptides Superdex 75 3,000–70,000 Da Peptides to small proteins Superdex 200 10,000–600,000 Da Large proteins, aggregates Sephadex G-10 <700 Da Desalting, buffer exchange
Equilibrate column with appropriate buffer (e.g., 50 mM ammonium acetate, pH 7.0)Dissolve sample in mobile phase (low volume for best resolution)Load sample onto columnElute isocratically with mobile phaseMonitor absorbance at 214 nm or 280 nmPool fractions and lyophilize
Non-denaturing conditions
No sample loss (non-binding)
Good for aggregate removal
Useful for desalting
Complementary to other methods
Lower resolution than RP-HPLC or IEX
Limited loading capacity
Dilutes sample
Column packing critical for resolution
Not suitable for large-scale production
├── Hydrophobic? → RP-HPLC (C18)
├── Charged? → IEX (CEX or AEX) → RP-HPLC
├── Aggregates present? → SEC → RP-HPLC
└── Simple sequence? → RP-HPLC alone
Sequence Type Recommended Strategy Simple, hydrophobic RP-HPLC only Charged, complex IEX → RP-HPLC Aggregate-prone SEC → RP-HPLC High purity required IEX → RP-HPLC → SEC Modified peptide Affinity → RP-HPLC
Parameter RP-HPLC IEX SEC Resolution High Moderate Low Loading capacity Moderate High Low Scalability Excellent Good Limited Solvent cost High (ACN) Low (buffers) Low Sample recovery 70–90% 80–95% 90–100% MS compatibility Excellent Poor (salts) Good Speed Fast Moderate Slow
Lascoux D, et al. “Purification of synthetic peptides.” Methods Mol Biol 2005;251:47-60.
Krishnamurthy R, et al. “Chromatographic purification of therapeutic peptides and proteins.” J Chromatogr B 2017;1055:61-76.
Boysen RI, et al. “HPLC purification of peptides.” Biochim Biophys Acta 2019;1867:39-52.
