LimsPulse
Chromatography

Gel Permeation / Size-Exclusion Chromatography (GPC / SEC)

Separates molecules by their size in solution rather than by chemistry, so large molecules elute first. Used for polymer molecular-weight distribution and for protein aggregates in biologics.

  • Pharmaceutical
  • Biopharmaceutical
  • Polymers & plastics
  • Food (polysaccharides)
  • Cosmetics
  • Chemicals
Photo of a Gel Permeation / Size-Exclusion Chromatography (GPC / SEC)
Photo: TheBartgry, CC0 (cropped), via Wikimedia Commons
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1

Before you start

  1. 1Prepare the mobile phase exactly as specified; for aqueous SEC, include salt to suppress ionic interactions.
  2. 2Dissolve samples slowly in mobile phase (polymers may need hours of gentle mixing); filter through a suitable membrane.
  3. 3Check that the column set and calibration standards match the method.
  • Do not switch a GPC column between incompatible solvents (e.g. THF and water) unless the supplier allows it; the packing can collapse.
STAGE 2

Start-up

  1. 1Increase flow slowly to the method rate; SEC columns are sensitive to pressure shocks.
  2. 2Let the RI detector reference cell purge and the baseline stabilise (this can take an hour or more).
  3. 3Inject a flow marker or the calibration standards to confirm elution volumes are stable.
  • RI detectors drift with tiny temperature changes; keep the instrument away from draughts and direct sun.
STAGE 3

Running samples

  1. 1Run narrow-distribution calibration standards across the molecular-weight range and fit the calibration curve.
  2. 2Run a system suitability or reference sample (e.g. a known polymer or a protein standard with monomer and dimer).
  3. 3Inject samples and check results against the calibration range; do not extrapolate outside it.
  • A small change in flow rate shifts elution volume and gives a large molecular-weight error; many labs add an internal flow marker.
STAGE 4

Shutdown

  1. 1Leave the column in mobile phase at low flow, or store it in the supplier's recommended storage solvent (e.g. with antimicrobial agent for aqueous columns).
  2. 2Flush salt buffers from the system before long shutdowns.
  3. 3Complete the usage and column logs.
In LimsPulse · Calibration Management

Keep every GPC / SEC in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how