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.
A corresponding error message can be found in the event log in Analyst® (View - Event Log - Windows Logs - Application)
Possible Causes:
- 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.
- 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.
- 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.
- High source temperature and/or ionization voltage (IS)
- Lowering those values will decrease the likelihood of DMS discharge.
- 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.
- LC flow
- Decrease the flow rate.
- Lower the percent of water as high water content facilitates DMS discharge.
- 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.
- 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.
- Source Gases (Gas 1 and Gas 2)
- SelexION® / SelexION®+ should not be operated with nitrogen for Gas 1 and Gas 2.
Resolution
Posted: now