What Is Mass Spectrometry (MS)?
Category: Quality
An analytical technique that identifies compounds by their molecular weight. Used alongside HPLC to confirm that a peptide is actually what the label claims.
Detailed Explanation
Mass spectrometry (MS) is an analytical technique that measures the mass-to-charge ratio of ions to identify and quantify molecules in a sample. For peptides, MS provides definitive identification by confirming the molecular weight matches the expected value for the target peptide. While HPLC tells you how pure a sample is, MS tells you what that sample actually is. Together, they provide comprehensive quality verification.
Practical Context
On a Certificate of Analysis, mass spectrometry results confirm peptide identity. The measured molecular weight should closely match the theoretical molecular weight of the target peptide. A significant discrepancy could indicate the wrong peptide, a truncated sequence, or other synthesis errors. Always look for both HPLC purity and MS identity confirmation on COAs from reputable vendors.
Frequently Asked Questions
Why do I need both HPLC and MS results?
HPLC measures purity (how pure the sample is) while MS confirms identity (what the sample actually is). A sample could be highly pure by HPLC but be the wrong compound entirely, which only MS would detect.
Related Terms
- Certificate of Analysis (COA) - A document from a testing laboratory confirming the purity, identity, and quality of a peptide product. Reputable vendors provide COAs for each batch, ideally from third-party labs.
- HPLC (High-Performance Liquid Chromatography) - The gold standard analytical method for measuring peptide purity. Separates components of a sample to determine what percentage is the desired peptide vs. impurities. Look for 98%+ purity.
- Endotoxin - A toxic substance released from bacterial cell walls. Endotoxin contamination in peptide products can cause fever, inflammation, and serious adverse reactions. Quality testing should check for endotoxin levels.