SelexION® and Selexion®+ - How to Avoid Discharge Error


Date: 12/06/2023
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For research use only. Not for use in diagnostic procedures.


Issue Description

DMS (differential mobility spectrometry) discharge can have multiple causes. The discharge occurs between the electrodes of the SelexION® electrodes and will cause instrument failure.

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A corresponding error message can be found in the event log in Analyst® (View - Event Log - Windows Logs - Application)

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Possible Causes:

  1. Separation Voltage (SV) is too high
  • Discharge happens more likely at higher SVs. Lower the SV in case the action points listed below do not help.
  1. DMS cell and electrodes are not properly installed
  • Make sure the DMS cell is installed square to the orifice plate, both thumbscrews are tight against the DMS cell without visible gaps.
  • Make sure the electrodes are installed correctly and the screws are tightened. Use the spacer tool and consider the correct alignment.
  1. DMS cell and electrodes are dirty
  • Use the routine cleaning procedure to clean the cell and the electrodes.
  • Always clean after a DMS discharge error occurred.
  1. High source temperature and/or ionization voltage (IS)
  • Lowering those values will decrease the likelihood of DMS discharge.
  1. Low probe positioning and high electrode protrusion
  • Change the vertical probe to < 2 mm.
  • Make sure the electrode protrusion does not exceed 0.5 mm.
  1. LC flow
  • Decrease the flow rate.
  • Lower the percent of water as high water content facilitates DMS discharge.
  1. Modifier
  • Inspect the modifier lines with a flash light and make sure that you don't have bubbles or sputtering in the modifier liquid line or curtain gas line.
  • Lower the modifier flow if you use the settings medium or high or lower the curtain gas as this will lower the modifier flow.
  1. Equilibration
  • Make sure to equilibrate the system for 40 minutes without modifier and LC flow.
  • Allow further 10 minutes of equilibration with modifier and LC flow.
  1. Source Gases (Gas 1 and Gas 2)
  • SelexION® / SelexION®+ should not be operated with nitrogen for Gas 1 and Gas 2.
 
 

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