Investigating the electrospray mass spectra of inorganic and organic antimony compounds

Positive- and negative ion electrospray mass spectra of commonly encountered organic antimony compounds, i.e., trimethylantimony dichloride (TMSbCl2) and trimethylantimony dihydroxide [TMSb(OH)(2)], and inorganic antimony compounds, i.e., potassium hexahydroxyantimonate [Sb(v)] and potassium antimonyl tartrate [Sb(III)] have been obtained using electrospray time-of-flight mass spectrometry (ES-TOF-MS). By operating the ES-TOF-MS instrument at high sample cone voltage (100 V), fragmentation information of TMSbCl2 and TMSb(OH)(2) was obtained. Positive ion electrospray mass spectra have been found to be more useful for the identification of organic antimony compounds, TMSbCl2 and TMSb(OH)(2), whereas negative ion electrospray mass spectra are more suitable for the identification of inorganic antimony compounds, Sb(v) and Sb(III). Based on the ES-MS results, a solution chemistry of TMSbCl2 and TMSb(OH)(2) was proposed. Peaks at m/z 183 and 185 corresponding to [(CH3)(3)SbOH](+) can be considered as a characteristic fingerprint for the identification of trimethylantimony species (TMSb) in an aqueous solution when using a positive ion ES-MS technique. The characteristic fingerprint was applied for the identification, of TMSbCl2, following its elution from a size-exclusion chromatography (SEC) column.