response and gain, tuning and calibration_MS5975c

[ricard]

I'm using a 5975c MS. What i'm trying to clarify is part of the tuning problem. The EM has rised constantly, as the EM gain, fairly proportional. Then i'have rised the gain in my methods too in the same way of the autotuning, but I've lost a lot of response_sensitivity over time when it should be the same??.. or not??? is not a detector problem???).

Another question is about tuning and calibration. In some cases is necessary to retune the ms often, but is really necessary to calibrate every time i tune?? how can i support the idea of maintaining the calibration??

[Alexandre]

If you do tune to check profile and that the MS works it is fine.
Re load your old tune file and ready to go.
But you need to recalibrate if your want to use new tune. Unless you need to know ratio of the same ions e.g. 57 m/z of hexane to 57 m/z of heptane.

Also looks like you need to clean source.

[ricard]

really it was a dirty source.

Otherwise, i'm a beginner and stills confuse. I use normalized gain methods, then i was expecting to hold the same signal over time, since EMvolt is adjusted to hold the gain of the method, is'n it? althought the current of electrons leaving the HED is affected due to a dirty source or other problems?¡¡.

Fixing a gain factor in the method, the EMvolts applied is calculated using the last calibration of the EMV vs gain curve, does it means appliying the EMvolts necessary to reach the target gain in the last gaintune ?¿? On the other hand, if i do autotune ( targeting abundances) can i use the gain factor in the method, if that's the case which is the EMgain applied?¿?

Thanks a lot.