Mass spectrometer

A method of mass spectrometry comprising:

• providing a first ion trap or ion guide;
• separating ions according to their ion mobility or rate of change of ion mobility with electric field strength in a device, said device being arranged downstream of said first ion trap or ion guide;
• applying one or more transient DC voltages or one or more transient DC voltage waveforms to electrodes forming said device;
• providing a second ion trap or ion guide arranged downstream of said device;
• receiving a beam or group of ions in said second ion trap or ion guide and partitioning said beam or group of ions such that a plurality of separate packets of ions are confined in said second ion trap or ion guide at any particular time, wherein each packet of ions is separately confined in a separate axial potential well formed within said second ion trap or ion guide.

A method of mass spectrometry comprising:

• providing a first ion trap or ion guide;
• providing a device for separating ions according to their ion mobility or rate of change of ion mobility with electric field strength, said device being arranged downstream of said first ion trap or ion guide;
• providing a second ion trap or ion guide arranged downstream of said first ion trap or guide;
• and
• passing ions from said first ion trap or ion guide to said device and onwards to said second ion trap or ion guide;
• and then
• passing at least some of said ions or at least some fragment, daughter, product or adduct ions derived from said ions from said second ion trap or ion guide onwards to said first ion trap or ion guide.

A mass spectrometer comprising:

• a first ion trap or ion guide;
• a device for separating ions according to their ion mobility or rate of change of ion mobility with electric field strength, said device being arranged downstream of said first ion trap or ion guide;
• and
• a second ion trap or ion guide arranged downstream of said first ion trap or guide wherein said first ion trap or ion guide is arranged to pass or transmit ions to said device and onwards to said second ion trap or ion guide, and wherein said second ion trap or ion guide is arranged to pass at least some of said ions or at least some fragment, daughter, product or adduct ions derived from said ions onwards to said first ion trap or ion guide.