LCMS SQD Low Response

Hello everyone...

My name is Riddham Patel and I am from India. I am using Agilent Single Quad MSD G6125C and frequently after preventive maintenance of the instrument, I face some issue, which I would like to put forward in community. After service engineer performs PM and tuning of the instrument every six months, initially the instrument performs as per the expectation, after a month, however, the instrument stops giving the response. To resolve this frequently occurring issues, I just retune the instrument every time and instrument runs properly until next PM. I am facing this issue since last couple of PMs. Last time, however, while tuning the instrument for resolving this same issue, I observed remarkable increase in the voltages of the detector (HV), which means that our detector's life is soon going to be end and we have to purchase one of the most expensive spare-parts of the instrument.

My question is, "Why does instrument encounter such kind of reoccurring issue of losing the response each time after tuning?"

I remain in the anticipation from your kind response.


  • Hi Riddham,

    Thanks for the interesting question! So, the voltage required to produce the same response from the electron multiplier (EM) will naturally rise over time as the EM ages. This electron multiplier is a consumable and will not last forever. Replacement of this part is normal during the lifetime of the instrument. If the system is heavily used, more ions are striking the detector and so the aging process will be faster and the EM will wear out faster. To recover the response, you are doing the right thing by performing an autotune. Its also a good move to have a PM every 6 months.

    You don't say how quickly your EM voltage is rising - could you give an idea of how the voltage changes with each autotune on your system?

    Many thanks


  • In tuning, u have noticed that detector voltage is increasing...means time to replace it..During autotune, it tried to adjust n passed becoz still little life is there in detector but after sometime again voltage gone high n response become low...So if better to replace this during PM...

Was this helpful?