JPH05290795

PURPOSE:To perform analysis regardless of a sample introduction method by putting an insulating material and a shielding plate between a plasma torch and a high-frequency coil and grounding them through a variable capacitor to control the plasma potential of ICP. CONSTITUTION:A shielding plate 10 is made up of metal tantalum, molybdenum or the like which has heat resistance and corrosion resistance against the radiation from an inductive coupling plasma (ICP) and passes the alternating field of a high-frequency coil 2 and is a non-magnetic material to make an open-loop so that an induced current does not flow, and also it is wound around a plasma torch 1 through an insulating material to be kept from being brought into contact with the coil 2. And the plate 10 is grounded to an analyzer tube 8 through a variable capacitor 11 and a switch 12. The switch is turned off to make ineffective the electric field shielding effect of ICP 9 at the time of being lighted and is turned on in the regular lighting to control the electric field shielding effect by adjusting the capacity of the capacitor 11.