Hydride generation systems with a mass spectrometric detector

Hydride generation system with a mass spectrometric detector 

Chromosorb W (AW, DMCS). The arsines are separated on this column and passed into a mass spectrometer operated in the electron impact mode (70 eV), with the ion source at 180 C. Ions with m/z of 76 and 78 for AsHa, 90 for CH3ASH2, 90 for (CH3)2AsH, and 103 and 120 for (CH3)3As are selectively monitored. The peaks at these m/z values are the most intense in the mass spectra of the arsines. The mass spectrometer used in the selective-ion monitoring mode serves as an element- and molecule-specific detector. This system allows arsenite to be determined by pH-controlled reduction (pH 5). Total inorganic and reducible methylarsenic compounds are reduced at pH 1 (eqn. 1)  

Marine organisms are known to contain, in addition to inorganic arsenic compounds and simple methylated arsenic compounds, the more complex arsenic derivatives arsenobetaine and ribosyldimethylarsine oxides [46, 47], These two complex derivatives are converted upon treatment with 2 M aqueous sodium hydroxide for three hours at 95 C to reducible arsenic compounds, arsenobetaine to trimethylarsine oxide (eqn. 2) and ribosyldimethylarsine oxides probably to dimethylarsinic acid (eqn. 3)  

An aliquot of a sample without digestion with base analyzed with this hydride generation system will provide information about the presence of inorganic arsenic compounds and simple methylated arsenic compounds. Analysis of another aliquot that has been treated with sodium 

DETERMINATION OF TRACE ELEMENT COMPOUNDS NOT REDUCIBLE TO VOLATILE DERIVATIVES 

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