Diagnosing gastrointestinal illnesses using fecal headspace volatile organic compounds

Figure 1 Quadrupole mass filter schematic: ionized gas enters the quadrupole through a slit and interacts with charged metal poles. Based on mass and charge, different ionized gases successfully pass through a second slit to a detector that measures the mass-to-charge ratio of the ionized gas (solid arrow), while other ionized gases will collide with metal rods and will not reach the detector (dotted line and asterisk).