Compact mass spectrometer

A miniature mass spectrometer comprising:

• an atmospheric pressure ionisation source;
• a first vacuum chamber having an atmospheric pressure sampling orifice or capillary, a second vacuum chamber located downstream of said first vacuum chamber, a third vacuum chamber located downstream of said second vacuum chamber and a fourth vacuum chamber located downstream of said third vacuum chamber;
• a first vacuum pump arranged and adapted to pump said first vacuum chamber, wherein said first vacuum pump is arranged and adapted to maintain said first vacuum chamber at a pressure <10 mbar;
• a first RF ion guide located within said first vacuum chamber;
• an ion detector located in said fourth vacuum chamber;
• wherein the ion path length from said atmospheric pressure sampling orifice or capillary to an ion detecting surface of said ion detector is ≤400 mm;
• wherein said mass spectrometer further comprises:
• a tandem quadrupole mass analyser, a 3D ion trap mass analyser, a 2D or linear ion trap mass analyser, a Time of Flight mass analyser, a quadrupole-Time of Flight mass analyser or an electrostatic mass analyser arranged in said third vacuum chamber and/or said fourth vacuum chamber;
• and
• a split flow turbomolecular vacuum pump comprising an intermediate or interstage port connected to said second vacuum chamber, an intermediate or interstage port connected to said third vacuum chamber and a high vacuum (“HV”) port connected to said fourth vacuum chamber;
• wherein said first vacuum pump is also arranged and adapted to act as a backing vacuum pump to said split flow turbomolecular vacuum pump;
• and
• wherein said first vacuum pump has a maximum pumping speed ≤10 m3/hr (2.78 L/s).

A method of mass spectrometry comprising:

• providing a miniature mass spectrometer comprising an atmospheric pressure ionisation source, a first vacuum chamber having an atmospheric pressure sampling orifice or capillary, a second vacuum chamber located downstream of said first vacuum chamber and a third vacuum chamber located downstream of said second vacuum chamber, a first vacuum pump arranged and adapted to pump said first vacuum chamber,
• a first RF ion guide located within said first vacuum chamber, an ion detector located in said third vacuum chamber, a split flow turbomolecular vacuum pump comprising an intermediate or interstage port connected to said second vacuum chamber and a high vacuum (“HV”) port connected to said third vacuum chamber, wherein the ion path length from said atmospheric pressure sampling orifice or capillary to an ion detecting surface of said ion detector is ≤400 mm, wherein said first vacuum pump is also arranged and adapted to act as a backing vacuum pump to said split flow turbomolecular vacuum pump and wherein said first vacuum pump has a maximum pumping speed ≤10 m3/hr (2.78 L/s);
• providing a tandem quadrupole mass analyser, a 3D ion trap mass analyser, a 2D or linear ion trap mass analyser, a Time of Flight mass analyser, a quadrupole-Time of Flight mass analyser or an electrostatic mass analyser in said third vacuum chamber;
• operating said first vacuum pump to maintain said first vacuum chamber at a pressure <10 mbar;
• and
• passing analyte ions through said first RF ion guide located within said first vacuum chamber.