An analytical method based on a semi-continuous hydride generator coupled on-line with a gas chromatograph and mass spectrometric detector was developed and used for the identification of hydride-forming antimony compounds, This method allows for the characterization of compounds based on their retention times and mass spectral data Organoantimony compounds were identified to be present in extracts of a freshwater plant, namely pondweed (Potamogetan pectinatus), This is the first time that such compounds have been detected in samples of biological origin, The problem of organostibine molecular rearrangements which have been reported to occur during the hydride generation process was also investigated, An experimental procedure is described that allows for the elimination of such rearrangements.