COMPARISON OF DYNAMIC FAST-ATOM-BOMBARDMENT LIQUID SECONDARY-ION MASS-SPECTROMETRY AND ELECTROSPRAY MASS-SPECTROMETRY COUPLED TO REVERSED-PHASE LIQUID-CHROMATOGRAPHY FOR THE DETERMINATION OF OLIGOSACCHARIDES IN SEAWATER

A method has been developed for determination of non-derivatised oligo saccharides by LC-MS at low concentration levels and in complex matric es of seawater and sediment pore water. Two ionisation techniques, dyn amic fast atom bombardment (FAB)/liquid secondary ion (LSI) MS and ele ctrospray ionization (ESI), were investigated and evaluated. The elect rospray using Li+ ions as adducts proved to be superior to the FAB/LSI -MS for the determination of non-derivatised oligosaccharides. The LC separation was accomplished by the use of a C-18 column and the elutio n either by a gradient of methanol-acetonitrile-water or pure water, i n which latter case the column was held at an elevated temperature. We also report results from measurements of oligosaccharides in pore wat ers of marine sediment cores. Oligosaccharides of a range from 2 to 6 sugar units were found in a concentration range of 2-100 nM, the small er sugars being more abundant. The depth profiles in the sediment core s indicate a production in the redox boundary layer and from there, di ffusion in both directions to the overlaying water and further down in to the sediment. (C) 1997 Elsevier Science B.V.