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Thermo Fisher Scientific

APCI Temperature fluctuation when using divert valve


I am using the divert valve with 1000 uL/min LC flow, and when it switches to divert the flow to the source, the vaporizer temperature drops ~40C below the setpoint before climbing back to the setpoint in 2-3 minutes.  When the divert valve switches the flow back to waste, the opposite effect happens.  Is this a problem?




This is normal behavior for the Ion Max APCI probe.   The temperature equilibrium is partially dependent on the LC flow rate, and to a lesser extent the source gas flows.   For this reason, the LC flow should be switched to the source far enough in advance to allow the temperature to resettle at the setpoint.


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