IDENTIFICATION AND DETERMINATION OF BUTYLTIN COMPOUNDS IN WATER BY ION-TRAP GAS CHROAMTOGRAPHY MASS-SPECTROMETRY AFTER CONVERSION TO METHYLOR HYDRIDE DERIVATIVES

Capillary column gas chromatography with ion trap mass spectrometric d etection has been shown to be a powerful technique for the determinati on of trace and ultratrace quantities of tributyltin and its degradati on products (di- and monosubstituted analogues) in water. Butyltins we re extracted into hexane in the presence of tropolone (0.2%, w/v) foll owed by either Grignard methylation or NaBH4 reduction to correspondin g butyltinhydrides to produce species of sufficient volatility. The wi de linear dynamic range (over three orders of magnitude) and pg sensit ivity obtained for the ion trap mass spectrometer operating in electro n impact (EI) mode has demonstrated the ability of this CC-Ms configur ation to provide routinely trace and ultratrace analyses of organotins . Two derivatization routes are compared, in combination with GC-MS us ing classical electron impact or chemical ionization (CI). Hydride der ivatization offers reduced labour effort and for most cases easier int erpretation of observed spectra. Grignard methylation provides lower d etection limits when using EI ionization and superior stability of sta ndard calibration solutions. CI detection mode using CI reagent gases methane, isobutane, acetonitrile a methanol was studied. Methanol and acetonitrile Cf provide simple mass spectra, yielding complementary sp ectral information to EI. The reported values of detection limits for acetonitrile CI are comparable to those using EI ionization mode. The acetonitrile CI mass spectra are characterized by the formation of [M( (FRAGMENT)) + 42](+) ions.