Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur

Instrumentation and analytical techniques were developed to measure isotope abundances from nanograms of sulfur and boron. Sulfur isotope compositions were determined employing continuous flow isotope ratio mass spectroscopy (CF-IRMS) procedures and AsS{dollar}sp+{dollar} thermal ionization mass spectrometry techniques (AsS{dollar}sp+{dollar}-TIMS). Boron isotope abundances were determined by BO{dollar}sb2sp-{dollar}-TIMS.; CF-IRMS measurements realized {dollar}deltasp{lcub}34{rcub}{dollar}S values from 10 {dollar}mu{dollar}g sulfur with precisions of {dollar}pm{dollar}0.3{dollar}perthous.{dollar} To extend sulfur isotope measurements to much smaller samples, a TIMS procedure was developed to measure {dollar}rmsp{lcub}75{rcub}Assp{lcub}32{rcub}Ssp+{dollar} and {dollar}rmsp{lcub}75{rcub}Assp{lcub}34{rcub}Ssp+{dollar} at masses 108 and 109 from 200 ng S on a Finnigan MAT 262 with an ion counter. This is possibly the smallest amount of sulfur which has been successfully analyzed isotopically. The internal precision of {dollar}rmsp{lcub}32{rcub}S/sp{lcub}34{rcub}S{dollar} ratios measured by AsS{dollar}sp+{dollar}-TIMS was better than {dollar}pm{dollar}0.15 percent. {dollar}deltasp{lcub}34{rcub}{dollar}S-values calculated relative to the measured {dollar}rmsp{lcub}32{rcub}S/sp{lcub}34{rcub}S{dollar} value of an IAEA AG{dollar}sb2{dollar}S standard (S-1) agreed with those determined by CF-IRMS to within {dollar}pm{dollar}3{dollar}perthous.{dollar} The increasing sensitivity of S-isotope analyses permits hiterto impossible investigations e.g. sulfur in tree rings and ice cores.; Boron isotope abundances were measured as {dollar}rm BOsb2sp-{dollar} from 50 ng B using an older thermal ionization mass spectrometer which had been extensively upgraded including the addition of computer control electronics, sensitive ion current amplification and fiber optic data bus. The internal precisions of the measured {dollar}sp{lcub}11{rcub}{dollar}B/{dollar}sp{lcub}10{rcub}{dollar}B ratios were {dollar}pm{dollar}0.15 percent and the precisions of {dollar}deltasp{lcub}11{rcub}{dollar}B values calculated relative to the accepted international standard (SRM-951) were {dollar}pm{dollar}3{dollar}perthous.{dollar}; Two applications of boron isotope abundance variations were initiated (1) ground waters of Northern Alberta and (2) coffee beans in different regions of the world. In the first it was demonstrated that boron isotopes could be used to trace boron released during steam injection of oil sands into the surrounding environment. Data from the second study suggest that boron isotopes can be used to improve cultivation of coffee particularly in regions where "organically grown" coffee had markedly different {dollar}deltasp{lcub}11{rcub}{dollar}B values than beans grown with boron-containing fertilizers in neighbouring regions. A regional dependence on the {dollar}deltasp{lcub}11{rcub}{dollar}B values of the coffee allow the sources of commercial coffee blends to be identified.