A mass spectrometer is disclosed comprising an ion guide or ion mobility spectrometer having helical, toroidal, part-toroidal, hemitoroidal, semitoroidal or spiral ion guiding region. A system includes a detecting apparatus, a directing control apparatus, an aiming control apparatus, a launch control apparatus, a launching device, and an intercepting device. This may be useful for treating a well for example as a fluid spacer or a scavenger; this may also be used a hydraulic fracturing fluid.