A new type of argon ionisation detector
A new type of argon ionisation detector is described that is constructed completely of glass and Teflon, and consequently is extremely inert. The production of metastable argon atoms appears to arise from the thermionic emission of electrons from the glass surface. The volume of the detecting cell is less than 5 µl and the applied voltage lies between 1000 and 2000 V, depending on the geometry. The detector can also function with helium as the carrier gas, without the need to subject the helium to excessive purification procedures. The detector in its experimental form appears to have a potential sensitivity at least equivalent to that of the flame-ionisation detector and a linearity of at least three orders of magnitude. Preliminary experiments indicate that the argon detector will detect all substances that the original model will sense and it appears to be extremeley inexpensive to fabricate. As a result of its low dead volume, this detector should be very useful for multi-dimensional separations employing capillary columns.