Emission analysis method with inductively-coupled radio frequency plasma and apparatus for use in such method

A method for analyzing a plurality of samples using Inductively-Coupled Radio Frequency Plasma (ICP), wherein said method employs an apparatus comprising a plasma torch means for supplying a pilot light plasma and for receiving a coolant gas supply;

• an induction coil disposed around the top of said plasma torch means for generating a radio frquency magnetic field;
• a radio frequency voltage source connected via an impedance matching unit means to said induction coil for supplying electric power thereto;
• and a switch valve means operatively connected to said plasma torch means wherein said switch valve means introduces said plasma torch means in a first position during an ICP analysis period, and said switch valve means prevents said sample from entering said plasma torch means in a second position;
• said method comprising the steps of:
• switching said switch valve means to said first position only during said ICP analysis period so as to introduce said sample into said plasma torch means;
• supplying said induction coil with a first volume of coolant gas in such a manner that said sample is introduced into said plasma torch means in the form of ionized plasma;
• analyzing said plasma of said sample;
• switching said switch valve means to said second position during periods except for said ICP analysis period;
• supplying said induction coil with a second radio frequency source of electric power and supplying said plasma torch means with a second volume of gas in such a manner that said pilot light plasma is maintained in said plasma torch means;
• and
• repeating the above steps, wherein the volume of electric power and gas consumed by said apparatus when said switch valve is in said second position is reduced from that consumed in said first position so as to reduce running costs for analyzing a plurality of samples.