Troubleshooting - Gilson PLC 2050 User Manual

Troubleshooting

Considering that the operator has already determined that other components of the system
are operating in an appropriate way, the following information can help to determine the
cause of the problem.
Never disassemble the nebulizer. Disassembling the rear part of the nebulizer (at the level of
NOTICE
the white engraved heat-shrinking tubing) will permanently damage it.
1. Check to ensure that the liquid level in the siphon is appropriate, and there is no liquid
pooling close to the evaporation tube inlet.
2. Check that the gas pressure is sufficient and stable. the selected pressure for most
applications is 2 bar (29 psi) and gas consumption is 3 L/min. Pressure above 4.5 bar
(67 psi) can damage the pressure sensor. the gas filter should be clean and in place. only
use gas free of particle and oil residue.
3. ensure that the flow rate of the pump is constant and check that there are no leaks in the
PLC system.
4. the mist from the nebulizer should be homogeneous. if it is not homogeneous, the
nebulizer, the needle or the Ptfe tube may be partially obstructed. to remove the
obstruction, pump a solvent that can dissolve the foreign material. as an alternative, the
nebulizer can be placed in an ultrasonic bath to dissolve the foreign material. instructions
about cleaning of the nebulizer are given on next page.
5. if the sensitivity of the detector is low, ensure that there are no leaks in the system. make
sure you are using a fresh sample and consider running the test using a backpressure
loop instead of a column. alternatively, the light source may need to be replaced or the
nebulizer could be obstructed.
6. a decrease in the sensitivity is often caused by the nebulizer (main cause). Clean the
nebulizer. if the sensitivity does not return to normal, the nebulizer might need to be
replaced. Please note that the root cause might also be in different module, i.e. volumes
injected by the autosampler might be too low or dead volumes in capillary connections
may cause peak broadening.
7. if the detector signal is saturated or if there is a decrease in the dynamic range of the
system, it is possible that a residue is passing through the detector cell. this will lead to
an intense signal due to a significant amount of light-scattering. this residue may be a
result of the elution of strongly retained materials from the column, or may come from the
solvent. to determine the cause of the problem, bypass the column and observe the signal
intensity.
● if the signal returns to normal, strongly retained materials are eluting from the column.
flush the column with a strong solvent to elute all material.
● if the signal does not return to normal, the solvent contains a too high residue material,
after evaporation and is not suitable for use with the detector.
8. if the noise of the detector without solvent is high or if ghost peaks occur, it is possible
that foreign material is present in the drift tube. in this situation, increase the temperature
to 95°C and pump appropriate solvent at the rate of 2 mL/min, using a gas pressure of
2.0 bar (29 psi). the solvent will be determined by the nature of the samples that were
previously analyzed with the detector. if you do not know the nature of the sample,
ethanol is a good choice. Do not use solvents that can potentially corrode the instrument.
maintain the flow and temperature during three hours at least.
PLC 2050/2250/2500 PurifiCation SyStemS PLC 2050/2250/2500 PurifiCation SyStemS
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