METHOD AND APPARATUS FOR ANALYSIS AND ION SOURCE

An ion source is formed by a chamber 2. A capillary tube 6 forms an inlet to the chamber. A heater 7 is associated with the capillary tube to heat air drawn into the chamber. An electrode 4 is provided in the chamber and maintained at a voltage in the range 100 to 500 volts. In use the source is connected to an analyser such as a mass spectrometer 10. The capillary tube is open to the atmosphere. Pressure in the chamber is reduced, and pressure in the analyser is further reduced. An electrical potential is applied to the electrode to create a discharge within the chamber. Ionisation of air molecules within the chamber leads to ionisation of any sample molecules present in the chamber. Ions are swept into the analyser for analysis.