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LCMS

LCMS

1. What LC-MS Stands For

LC-MS = Liquid Chromatography – Mass Spectrometry It’s a two-stage analytical method combining:

  1. Liquid Chromatography (LC) → Separates compounds in the sample.
  2. Mass Spectrometry (MS) → Measures the exact mass of each compound to confirm identity.

2. Purpose in Peptide Testing

  • Identity → Confirms the peptide’s molecular weight matches what it’s supposed to be.
  • Purity → Detects how much of the sample is the target peptide vs. impurities or degradation products.

3. How the Process Works

Step 1 – Sample Prep

  • A small amount of the lyophilized peptide is dissolved in a suitable solvent (usually water, acetonitrile, or buffer).
  • The solution is filtered to remove particulates.

Step 2 – Liquid Chromatography

  • The sample is injected into an LC column.
  • The column separates different components based on polarity and interaction with the stationary phase.
  • Output is a chromatogram → peaks represent different compounds.

Step 3 – Mass Spectrometry

  • As compounds exit the LC column, they’re ionized (given an electrical charge).
  • MS measures their mass-to-charge ratio (m/z).
  • This produces a mass spectrum → a fingerprint of the molecule’s weight.

4. What the Report Shows

A typical Janoshik or high-quality LC-MS report will have:

  1. Chromatogram → Shows separation and purity (target peptide should be the main peak).
  2. Mass Spectrum → Shows the measured molecular weight vs. the theoretical molecular weight.
  3. Purity Percentage → Usually from integration of the LC peaks.
  4. Notes → Sometimes includes observed modifications, truncations, or unexpected impurities.

5. Interpretation

  • Identity Match → Measured MW is within a tight tolerance (±0.1 Da) of the expected value.
  • Purity →
    • 95–99% = Pharmaceutical grade.
    • 90–95% = Research grade, still acceptable for many studies.
    • Below 90% = Significant impurities — may include synthesis byproducts or degradation.

6. Limitations

  • LC-MS does not test sterility — it’s purely chemical analysis.
  • Some impurities may be invisible if they don’t ionize well.
  • Peptides with unusual modifications may require MS/MS (tandem MS) for full confirmation.

7. Why It’s the “Gold Standard”

  • Extremely precise — can detect mass differences down to fractions of a Dalton.
  • Shows both what’s in the vial and how much of it is the intended peptide.
  • Publicly verifiable reports from labs like Janoshik have become a trust anchor in the peptide community.