signal reducing in LC mass

[Chandresh K. Soni]

Hello friends,

I have one LC Mass from waters model quattromicro. I have two problems in Lc mass

1. we are not getting the current stability in APCI negative mode it is continuously fluctuating while in positive mode we are gettingne of th constant current. this one is happening from day one of installation. is waters quattromicro instrument are running in this way.

2.i am getting continuously reducing signals of the solvents. i think someone taking the phosphate buffer as mobile phase. can anybody suggest me what happen if phosphate buffer is taken as buffer in LCmass. up to what extent the contamination is happen.I had checked with calibration and getting the calibration is ok but still i can't understand the phenomenon of reducing theome signals.

Hope someone understand my problem and provide me the suitable solution.

thanks to all

[Alexandre]

Hi Chandresh

Can you replace the phosphate buffer as mobile phase?
I only use volatile buffers.
I found that it is a balance between sensitivity and buffer strength (needed also for stability of tR etc.).

[Chandresh K. Soni]

thanks alexendra,
actually by mistake someone in our lab phosphate buffer used which is actually a mobile phase for LC(not for LC mass but only to check the signal).
still we dont know what is the exact problem even now we are not getting the signals properly even with in two minutes our signals were disappears. if u have any ideay please suggest us.