ONLINE SULFUR-ISOTOPE DETERMINATION USING AN ELEMENTAL ANALYZER COUPLED TO A MASS-SPECTROMETER

An on-line method for S-isotope analysis is described. Samples are com busted in an elemental analyzer. SO2 is separated from other combustio n gases by gas chromatography, and the gases enter the ion source of t he mass spectrometer through a split interface. Integrated peak areas for (SO2+)-S-32 and (SO2+)-S-34 are compared to the response for a sta ndard gas sample to determine the delta(34)S value. delta(34)S values of samples analyzed using the on-line method correspond Linearly with those achieved from the same sample prepared off-line, where Kiba redu ction followed by oxidation of the sulfur to SO2 is carried out prior to S-isotope analysis against a known standard. With the described on- line method, the amount of sulfur necessary for S-isotope analysis is reduced to about 10 mu g of S per analysis. The time needed for on-lin e preparation and measurement is less than one-third of the off-line p rocedure.