HPLC vs Mass Spectrometry
Two analytical methods answer two different questions about a research peptide. Here is what each one proves, and why a credible COA needs both.
Two Different Questions
HPLC and mass spectrometry are often listed side by side on a COA, but they measure fundamentally different things. HPLC answers "how pure is this sample?" Mass spectrometry answers "is this actually the molecule it claims to be?" Neither alone is sufficient: a sample can be 99% pure but the wrong peptide, or the correct peptide contaminated with impurities. Only together do they establish that a vial is both the right compound and a clean one.
What HPLC Measures
High-Performance Liquid Chromatography separates the components of a sample as they pass through a column, with detection commonly at 214 nm — the wavelength absorbed by peptide bonds. The result is a chromatogram in which each component appears as a peak. Purity is calculated from the area of the target peptide's peak relative to the total. A single dominant peak with few minor peaks indicates a high-purity sample.
What Mass Spectrometry Measures
Mass spectrometry ionizes the peptide — often by electrospray ionization (ESI) — and measures its mass-to-charge ratio with high precision. The measured molecular weight is compared against the theoretical weight derived from the amino-acid sequence. A close match confirms the peptide's identity and can reveal structural problems such as truncations, oxidation, or incorrect sequences that purity testing would miss.
Why Both Matter
Because purity and identity are independent properties, a trustworthy COA reports both. Reading the two together is what lets a researcher confirm that the material in the vial is the intended compound at a known purity — the foundation of reproducible experimental results.
For laboratory and research use only. This guide describes general handling and analytical practice for research reagents and is not medical advice or dosing guidance for human or veterinary use.