Understanding HPLC & Mass Spectrometry Purity Analysis in Research Compounds

### Analytical Validation of Research Peptides High-quality peptide synthesis requires strict verification to distinguish authentic full-length target peptides from deletion sequences, truncated fragments, and protecting-group adducts. ### Reverse-Phase HPLC (RP-HPLC) RP-HPLC separates peptide molecules based on their hydrophobic interactions with a C18 bonded stationary silica phase under high pressure: - **Chromatogram Retention Time**: Each peptide elutes at a characteristic retention time based on its amino acid hydrophobicity gradient (acetonitrile/water with 0.1% TFA). - **Area Under the Curve (AUC)**: Purity is quantified by integrating the main absorption peak against minor background noise peaks at UV wavelength 214 nm or 220 nm (the peptide bond absorption spectrum). - **Target Standard**: USA Peptide Depot guarantees a minimum threshold of **>99.0%** chromatographic purity across all research lots. ### Electrospray Ionization Mass Spectrometry (ESI-MS) While HPLC confirms chromatographic homogeneity, Mass Spectrometry confirms the exact chemical identity and molecular formula weight: - **Mass-to-Charge Ratio (m/z)**: Measures protonated molecular ions ([M+H]^+), ([M+2H]^{2+}), and ([M+3H]^{3+}). - **Deconvolution**: Reconstructs the exact observed monoisotopic molecular weight and validates it within $pm 0.5$ Da of theoretical molecular weight.