Abstract

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)₃SbOH]⁺ 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.