Isobutane plasma

Spectrum of the isobutane plasma under chemical ionization conditions at 200 pbar. 

This isobutane plasma will be very inefficient in ionizing hydrocarbons because the /-butyl cation is relatively stable. This characteristic allows its use in order to detect specifically various substances in mixtures containing also hydrocarbons. 

An afterglow microwave plasma with stabilized pulse power was applied to the activation of zeolite catalysts for isobutane alkylation with butenes. It was found that the pretreatment of zeolite catalysts in a microwave plasma discharge affected their properties. The catalysts exhibited higher activity, stability in operation, and selectivity (the fraction of trimethylpentanes in the alkylate increased). The properties of catalysts after plasma activation depend on the treatment conditions such as plasma temperature and nonequilibrium character and depend only slightly on the initial activity of catalysts, which is primarily controlled by the catalyst preparation conditions. 

Chemical ionization (Q) source is very similar to the El source but the beam of electrons is used to create a plasma of ionized reagent gas (e.g., isobutane, methane, ammonia). 

A similar method of direct analysis has been used to identify and quantitate the antiarrhytmic agents, quinidine ( ) and lidocaine (11) in human plasma (17). In one experiment a known amount of d2 "dihydroquinidine (9 ) was added to plasma samples from patients who had received quinidine gluconate, and the extract was applied directly to the probe of the mass spectrometer. The resulting isobutane spectrum obtained (Fig. 2) clearly shows the ion... 

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