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Varian ELSD Service Manual
Installing the Detector
Connect the power cord to the IEC inlet at the rear of the unit.
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Check the operating voltage of your instrument, 110V 2A or 230V 2A, on the IEC inlet fuse-holder on rear
of unit.
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Attach the gas inlet tube to the gas inlet at the back of the instrument.
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The gas connection is a 4mm OD push-in fitting. The nitrogen gas should be dry, filtered and have a
minimum inlet pressure of 60psi, 60-100psi is required to achieve the maximum operating instrument gas flow
rate of 3.25 SLM throughout the temperature range.
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Connect the waste tube to the waste outlet at the front of the detector and position the other end in a waste
collection bottle.
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The solvent waste container supplied with the detector can be sited on the bench in front of the instrument.
Alternative waste collection vessels can be used if required but the bottom of the waste tube must be below the
height of the waste outlet from the instrument. The waste tube must NOT be submerged in the liquid.
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Connect the exhaust hose between the exhaust outlet and a fume hood.
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Connect the instrument to the data recorder (computer, chart recorder, etc.) using the cable provided. One
output socket is provided giving a signal in the 0-1V range.
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Connect the column outlet to the eluent inlet at the front of the unit) using a short length (10cm) of tubing
(1/16” OD, 0.010” ID) and a 1/16” Valco fitting.
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Turn on the source gas to a pressure of about 60-100 psi. The gas will not flow though the detector until
the instrument in set to RUN mode.
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Switch on the ELSD and select method “XXX”.
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Start heating by selecting RUN mode using the arrow keys on the front keypad.
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When the unit has equilibrated, the baseline should be checked to ensure that it is acceptable for the
experiment. At this point, with no liquid flowing into the instrument, the noise should be no more than 0.3mV
peak-peak. This verifies that the gas supply is clean and dry. Any spikes in the baseline are usually indicative
of particulate matter or water in the gas supply.
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Turn on the eluent flow and allow the system to stabilize for approximately 15 minutes.
THE ELUENT FLOW CAN BE TURNED ON BEFORE THE INSTRUMENT HAS
REACHED EQUILIBRIUM. IF THE ELUENT IS NOT EFFICIENTLY NEBULISED IT WILL
EXIT THE INSTRUMENT FROM THE NEBULISER DRAIN TUBE.
•
Again check the baseline noise as it should not have increased significantly. and should be
<
1mV.
Typically the baseline noise is 0.3mV peak-peak.
If the baseline noise is excessive, then one of the following may be taking place: -
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poor evaporation due to gas flow being too low
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poor evaporation due to evaporation temperature being too low
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poor nebulisation due to temperature being too high and solvent boiling
Any of these problems will cause the baseline to shift upwards, as the amount of scattered light within the instrument
has increased. If the baseline continues to show unacceptable noise even when the evaporation conditions have
