I. Fernandezescobar et al., COMPLETE ELIMINATION OF INTERFERENCES IN THE ORGANOTIN DETERMINATION BY OXIDATION WITH DIMETHYLDIOXIRANE COMBINED WITH ALUMINA CLEANUP, Analytical chemistry (Washington), 70(17), 1998, pp. 3703-3707
Most of the analytical procedures used in organotin (OT) speciation fr
om sediment involves the Grignard derivatization reaction followed by
a cleanup step and a desulfuration reaction since sulfur and/or sulfur
species interfere with OT determination by GC/MS or GC-FPD. However,
alkyl sulfides are generated from the coextracted elemental sulfur, an
d they are not removed by conventional desulfurization procedures. We
propose here a method based on the oxidation of all the sulfur species
with dimethyldioxirane (DMD) to sulfones or sulfur oxides. While sulf
ones are easily eliminated by alumina adsorption chromatography becaus
e they have higher polarity than OTs, the sulfur oxides are spontaneou
sly evaporated. The DMD chemoselectivity favors the oxidation of sulfu
r compounds to sulfones in a few minutes, whereas OTs remain unreacted
. In addition, the excess DMD is easily removed by evaporation under a
nitrogen stream before the Al2O3 cleanup step. The effectiveness of t
he desulfurization reaction combined with the cleanup step is demonstr
ated for a variety of sediment samples containing up to 3.1% of elemen
tal sulfur, which is completely removed by adding 0.6 molar equiv of D
MD. No statistical differences in the OT distribution pattern througho
ut the DMD intermediate oxidation steps were observed.