The microwave-induced electrical discharge plasma MIP detector

The microwave-induced electrical discharge plasma (MIP) detector 

An argon or helium plasma is sustained in a microwave cavity which serves to focus or couple power from a microwave source, usually operated at 2.45 GHz, into a discharge cell which is a capillary tube, made of quartz, boron nitride, alumina etc.. Microwave plasmas of different cavity designs may be operated at atmospheric or under reduced pressures [12, 13]. The 50-100 watt power levels for analytical microwave plasmas are much lower than for the DCP or the ICI giving 

Another type of microwave plasma cavity which has been used successfully in GC-MIP is the Surfatron which operates by surface microwave propagation along a plasma column [17]. The plasma may be viewed axially or transversely since it extends outside the plasma structure it can sustain a dicharge over a wide pressure range. 

Interfacing TMqio cavities with packed GC columns is more diflScult since the plasma is extinguished by the vapor burst from the solvent and may also be disrupted by large sample peaks. Packed columns are of value, however, particularly for trace determinations when resolution 

The microwave-induced plasmas (MIP) have been much more eflfec-tive in GC than in HPLC interfacing, the latter having been developed most with the high powered DCP and ICP argon plasmas which are able to tolerate mobile phase solvents at the flow rates used in liquid chromatographic procedures. The low powered helium MIP cannot be eflfectively interfaced to conventional HPLC columns, since the 

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