Contact & Information

HPLC Troubleshooting

Keine Peaks, die Baseline ist absolut flach

No peaks, baseline is absolutely flat

  1. The lamp in the detector is switched off or defective
  2. The connection cable between detector and control computer is not connected
  3. No flow of solvent
  1. Switch on or replace the lamp on the detector
  2. Check all cables and connections
  3. Check storage vessel, start pump(s)

Keine Peaks, Baseline zeigt leichtes Rauschen

No peaks, baseline shows slight noise.

  1. Wrong flow direction
  2. No, too little, wrong sample injected
  3. Wrong sensitivity / wavelength of the detector
  1. Set up and start pumps correctly
  2. Check samples or autosampler
  3. Check settings on the detector

Hohes Rauschen mit regelmäßigen Zacken

Strong noise with regular peaks.

Strongly pulsating flow of solvent.
  1. Check pumps, possibly air bubbles in the valve on the pump head
  2. Use pulsation damper

Hohes Rauschen mit langer flacher Drift

Strong noise with long flat drift.

Presumably temperature fluctuations due to external radiation.
  1. Move the HPLC column into the column thermostat
  2. Protect the HPLC system from changing ambient temperatures

Hohes Rauschen mit scharfen negativen Zacken

Strong noise with sharp negative spikes.

Probably electromagnetic interference.
  1. Use shielded cables
  2. Use a power supply with galvanic isolation (UPS)
  3. Connect the complete HPLC system to a different circuit

Extrem starkes Rauschen

Extremely strong noise.

Air bubbles in the flow cell in the detector.
  1. Rinse flow cell until air is removed
  2. Use a back pressure restrictor at the inlet of the flow cell
  3. Use a solvent filter and/or degas the solvent

Gleichmäßiges Rauschen

Regular noise.

  1. The mixer is defective
  2. Defective lamp in the detector
  3. Eluent absorption too high
  1. Check mixer
  2. Replace lamp
  3. Change eluent / wavelength

Unregelmäßiges Rauschen

Irregular noise.

Flow cell in the detector dirty.
Rinse flow cell with org. solvent or 20% HNO3.

Keine Peaks und kein Rückdruck, kein Fluss am Detektor

No peaks and no back pressure, no flow at the detector.

  1. Pump(s) is/are switched off
  2. Air bubble in valve at pump head
  3. Leakage at connection or suction hose defective
  4. Supply vessel empty or suction hose not in running medium
  1. Check pump(s) and switch on
  2. Rinse pump head and tap lightly on valve
  3. Check / seal or renew connections
  4. Refill eluent, fasten suction hose

Keine Peaks aber hoher Rückdruck bzw. Alarm

No peaks but high back pressure or alarm.

  1. Suction hose or filter clogged
  2. HPLC column or frit clogged
  3. Sample feed valve or sample loop clogged
  4. Capillary squeezed / plugged at port
  1. Remove blockage, clean  filter in ultrasonic bath or replace.
  2. Rinse column and clean  frit in ultrasonic bath or replace
  3. Disassemble and clean valve, rinse or replace loop
  4. Cut off damaged area of capillary and reconnect it

Langsamer Druckanstieg

Slow pressure increase.

  1. Frit at column inlet or column clogged.
  2. Frit clogged in mixer.
  1. Use / replace pre-column, possibly counter-rinse column.
  2. Clean frit in ultrasonic bath or replace.

Plötzlicher Druckanstieg

Sudden pressure increase.

  1. Defective or poorly switching valve.
  2. Sample has precipitated.
  1. Check and clean valves
  2. Rinse column or system

Druck­schwankungen

Pressure fluctuations.

  1. Air in the pump or in the suction line to the pump
  2. Leaky line between pump and column
  1. Degas the solvent or purge with helium.
  2. Tighten the screw connections of the lines.

Druckverlust

Pressure drop.

  1. No flow of the mobile phase
  2. Leaky liquid line between pump and column
  1. Check the system for loose screw connections and eluent reservoirs.
  2. Systematically search for and eliminate leakage.

Hoher Druckanstieg

High pressure increase.

  1. Contaminates at the column inlet, precipitation of buffer salts.
  2. Viscosity of the mobile phase is too high
  3. Particles of the column material are too small
  1. Remove column and backwash with strong solvent. Replace clogged filter elements and pre-column. Does the solvent match the buffer concentration?
  2. Change solvent or increase column temperature.
  3. Use HPLC column with larger particles (e.g. 8 µm instead of 5 µm).

Tailing, an Basis unscharfe Peaks, oft mit verschobener Retentionszeit

Tailing, blurred peaks at base, often with shifted retention time.

HPLC column overload
Reduce feed concentration or use column with higher capacity.

Fronting, ohne Verschiebung der Retentionszeit

Fronting, without retention time shift.

  1. Dead volume between injector and column.
  2. HPLC column defective.
  1. Check injector / tubing for dead volume.
  2. Replace HPLC column.

Breite, flache Peaks mit Dach

Broad flat peaks with roof.

The injection volume is too high.
Use smaller injection volume or smaller sample loop at injection valve

Doubling, alle Peaks haben zwei Maxima

Doubling, all peaks have two maxima

  1. Channel formation in the column.
  2. Injector defective.
  1. Replace HPLC column.
  2. Check and repair injector.

Verschiebung der Retentionszeiten in eine Richtung

Retention time shift in one direction.

  1. Leaking pump seal.
  2. Column overload.
  3. Column not equilibrated.
  1. Replace pump seals
  2. Inject lower sample concentration
  3. Equilibrate 2 to 3 column volumes

Willkürliche Verschiebung der Retentionszeiten

Arbitrary retention time shift.

  1. Temperature fluctuations of the column.
  2. Valve on pump head or proportioning valve defective
  1. Use column thermostat.
  2. Check / replace valves.

Peaks sind deutlich kleiner als erwartet

Peaks are significantly smaller than expected.

  1. Injection volume too low.
  2. Eluent with higher adsorption.
  3. Dirty flow cell in detector.
  1. Check injection volume.
  2. Use suitable (HPLC-grade) eluent.
  3. Rinse flow cell in detector.

Reproduzierbare Geisterpeaks

Reproducible ghost peaks.

  1. Dirty injection valve.
  2. Peak from previous run.
  3. Injection with air.
  1. Rinse injection valve.
  2. Run previous run longer.
  3. Check injection volume.

Willkürliche Geisterpeaks

Arbitrary ghost peaks.

  1. Sample solvent is contaminated.
  2. Air in flow cell in detector.
  3. HPLC column is dirty.
  1. Re-prepare sample.
  2. Rinse flow cell, use backpressure restrictor.
  3. Rinse or replace HPLC column.

Am Fitting tritt Medium aus

Medium leaks at fitting.

Tubing at the end of the ferrule is too long.
  1. PEEK tubing: shorten to correct length and reassemble.
  2. Stainless steel tubing: detach tubing including the ferrule, remove burr and mount with new ferrule.

Am ersten Peak bildet sich eine leichte Vorschulter

A slight shoulder forms at the first peak.

Dead volume at the end of the tubing, space between the end of the tubing and the connecting part, tubing is too short.
  1. Push the PEEK tubing to the maximum length into the loosened screw connection and tighten again.
  2. Stainless steel tubing: detach tubing including ferrule, remove burr and mount with new ferrule.