MS instruments must maintain a flow of drying Gas and, Nebulizer, AJS

Hi, Anyone please help me to explain Why must maintain the flow of drying Gas and, Nebulizer, AJS when the instrument in standby?

  • To ensure that the spray chamber continues to only contain nitrogen; specifically keeping oxygen out of the spray chamber/capillary/vacuum system.


  • Thanks Andy.

    Could you tell clearly the effect of keeping oxygen out of Spray chamber/Capillary/Vacuum system? Because if it affected to system, when I vented system for long time in not use, maybe in contradiction with that. And as I know, with MS Waters system, it doesn't need to keep the nitrogen flow when the system is in standby status.

  • The source of your instrument is connected to the waste bottle via the plastic corrugated tube. The Mass spec is under vacuum and is always drawing from the source, Usually this is nitrogen and it is exiting the source with a very small positive pressure. If the nitrogen supply is lost, the MS still pulls vacuum and must take something from somewhere and can then back stream from the waste container and contaminate the system. Worst case if the exhaust from your rough pump and waste bottle are not separate, as recommended in the site prep checklist, oil mist from the pump exhaust can be back streamed into the source and then further into the instrument.

  • Yep! But I'm comparing to MS system of Waters corp., to seen that Agilent need to improve this. Their system usually will turn off Nitrogen gas when the system in Standby status. This is really a benefit, because will help to check MS system issues separately with Generation Nitrogen gas when no have nitrogen flow gas. 

  • If you vented the system, then there is no need for nitrogen supply since the capillary and quadrupole temperatures are not kept high.  The system is vented using nitrogen from the gas supply, so the inside of the vacuum chamber is kept free of oxygen and moisture.  If left vented for a long period of time, any oxygen and moisture will be pumped away as the system is brought back under vacuum.

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