Poor peak area precision/peak areas too small

Possible Cause

Remedial Action

Air bubbles in sample loop, needle, or metering device

Purge the autosampler.

Vial empty

Check the sample level in the vial. If the sample level is too low, replace the vial with a filled one.

Contamination or carry-over

Possible Cause

Remedial Action

Contamination in the system

Flush the system using an appropriate solvent. If you use water as solvent in pump channel A, flush it with 80% acetonitrile.

Autosampler carry-over due to contaminated needle

  1. Check whether one of the needle wash lines (labeled SWP and WWP) is squeezed.

  2. Check whether one of the needle wash reservoirs is empty. If one of the reservoirs is empty, replace it by running the script: B01 - Change Liquids / Solvents. Use an appropriate needle wash liquid (see Filling the Needle Wash Reservoirs).

  3. Check whether the needle wash is deactivated in the chromatography data system. If yes, activate the needle wash.

  4. To wash the needle and needle seat, run the script: B03 - Clean Up System.

  5. If carry-over persists, replace the needle unit and the needle seat (see Replacing Needle Seat and Needle Unit).

Autosampler carry-over due to worn or damaged needle seat

Replace the needle seat (see Replacing Needle Seat and Needle Unit).

Instable analysis or poor reproducibility

Possible Cause

Remedial Action

Unstable environmental conditions

  • Make sure that the temperature and air humidity are constant. For information on the specified environmental conditions, refer to the operating manual of the detection device.

  • Use column thermostatting.

  • If the sample allows cooling, cool the sample in the autosampler.

  • Avoid draft.

Irreproducible gradient

  • Check the value for %B. If it is outside the range 1-99, correct it.

  • The system is not properly equilibrated. Let the system equilibrate for 5 hours.

  • Purge the pump.

Leakage

Possible Cause

Remedial Action

Capillary connections not installed properly or not tight

  • Run the script: D02 - Test System Tightness (What Should Be Tested = System).

  • Inspect the capillary and replace it if necessary.

Sample problems

Possible Cause

Remedial Action

Sample is unstable and decomposes

  • Cool the sample in the autosampler.

  • Use a new sample.

  • Change the environmental conditions.

Injection volume variation

Possible Cause

Remedial Action

Autosampler draws air from vial

There is not enough sample in the vial or the needle height setting is incorrect.

  • Check the sample level in the vial. If the sample level is too low, replace the vial with a filled one.

  • To check whether the needle is clogged, run the script: D01 - Test System Back Pressure. Follow the instructions.

Air trapped in autosampler flow path

Purge the autosampler.

Gas content of sample too high or saturated

Degas the sample if possible.

Injector needle clogged or needle tip deformed

Run the script: D01 - Test System Back Pressure. Follow the instructions.

Piston seals in autosampler metering device leaking

Run the script: D02 - Test System Tightness (What Should Be Tested = Sampler). Follow the instructions.

Injection valve or other autosampler components leaking

Run the script: D02 - Test System Tightness (What Should Be Tested = Sampler). Follow the instructions.

Needle seat worn out

Run the script: D02 - Test System Tightness (What Should Be Tested = Sampler). Follow the instructions.