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Knowledge base

Knowledge Base: HPLC and GC Troubleshooting

Do not invent a fix from an error code you have not verified on your instrument. Message text differs by brand and firmware. Use the symptom.

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Quick checklist (PDF)

Stop and call

These notes are for routine faults on HPLC and GC. They are not a repair manual. Stop if you meet a gas leak, a hydrogen alarm, a cracked fitting, or a result that does not change after the safe check. Call Mahut on +968 71130316.

Call +968 71130316
HPLC

HPLC

Pressure, peaks, retention time, and bubbles in the solvent path.

  • HPLC

Pressure is higher than normal

Blockage in the guard, column frit, inline filter, or tubing. Buffer salts are a common cause.
Read the checks
  • HPLC

Pressure is lower than normal

A leak, a loose fitting, a worn pump seal, or a column that is not the method column.
Read the checks
  • HPLC

The pump does not build pressure

Pump not running, flow at zero, prime valve open, empty bottle, air in the inlet, or a large leak.
Read the checks
  • HPLC

Pressure fluctuates

Fast ripple: air or a check valve that is not seating. Slow wander: a small leak, a blocked inlet frit, or poor degassing.
Read the checks
  • HPLC

Baseline noise

Noise is fast and jagged. Drift is a slow rise or fall. Usual HPLC causes: aging UV lamp, dirty flow cell, bubbles, or pump pulsation.
Read the checks
  • HPLC

No peak

No injection, detector or lamp off, wrong channel, flow going to waste, or the sample never reaching the column.
Read the checks
  • HPLC

Peaks are smaller than usual

Partial injection, degraded standard, wrong wavelength, weak lamp, or column loss.
Read the checks
  • HPLC

Retention time has changed

All peaks move together: flow, temperature, or solvent composition. Peak spacing changes: pH, the wrong column, or a contaminated column.
Read the checks
  • HPLC

Peaks move from one injection to the next

Incomplete equilibration, unstable oven, evaporating premixed solvent, or unstable proportioning.
Read the checks
  • HPLC

Bubbles in the solvent path

Bubbles before the pump: empty bottle, loose inlet, frit above the liquid, or solvent not degassed. Bubbles after the pump: leaking seal or check valve.
Read the checks
GC

GC

Peaks, inlet and detector pressure, gas supply, and baseline noise.

  • GC

No peak

No real injection, detector not ready, column not connected or broken, oven program too short, or split so high the peak disappears. An FID with no flame gives no peaks.
Read the checks
  • GC

Peaks are smaller than usual

Less sample reached the column, or the detector is less sensitive: partial syringe plug, septum or column-nut leak, split too high, or a dirty liner.
Read the checks
  • GC

Inlet or detector pressure error

Inlet: gas off, septum or ferrule leak, column broken or not installed, plugged split vent, or column length and inner diameter in the method that do not match the column. Detector: makeup gas, or FID hydrogen or air, depending on the message.
Read the checks
  • GC

Gas generators and cylinders

Empty or isolated cylinder, wrong regulator setting, wrong gas on the fitting, or a generator alarm. An exhausted trap usually ruins the baseline. It rarely removes all pressure.
Read the checks
  • GC

Baseline noise

A smooth rise at the top of the oven program can be normal column bleed. A sudden noisy baseline is not. Causes: dirty liner, septum particles, poor gas, an exhausted trap, or an unstable FID flame.
Read the checks
Safety

When to stop and call

Call +968 71130316 when:

  • You smell gas, or a hydrogen or leak shutdown is active
  • Pressure stays wrong after the column is isolated or the gas supply is confirmed
  • A fitting, column, or syringe is damaged
  • The detector, pump, or autosampler reports a fault you cannot clear with the checks above
  • A fresh standard still fails after one careful pass through the relevant checks
Call +968 71130316
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Corrective maintenance

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Book a consultation

Use a consultation to plan maintenance, review a recurring fault, or decide whether an instrument needs a visit now. If the instrument is already stopped, call +968 71130316.

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Call +968 71130316