Basics on ion formation

[Ricardinio]

I would like to understand clearly how unwanted ions (negative ions in positive ion polarity mode and positive ions in negative ion polarity mode) are eliminated in the ion source?

[BigGeoff]

Hi Ricardino

In positive ion mode, the positive ions formed in the source are accelerated towards the mass analyser region by a more negative voltage on the exit lens, the reverse is true for negative ion mode. The unwanted ions are either pumped away or collide with the source body.