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Rationale: Preparation of BaSO4 from samples of atmospheric rain, snow, and aerosols has been used for δ18O and δ34S analyses. In the present study, we investigated the effect of various sample pretreatments on δ18O and δ34S values determined from a Na2SO4 reagent solution and samples of atmospheric precipitation to improve assay time and cost efficiency. Methods: BaSO4 was prepared from a Na2SO4 solution by (a) evaporative concentration, (b) evaporation to dryness, (c) evaporation to dryness after adding HCl, and (d) evaporation to concentration after adding HCl, followed by cooling and then precipitation using a BaCl2 solution. To analyze the atmospheric precipitation samples for δ18O, BaSO4 prepared from the samples was treated with diethylenetriaminepentaacetic acid (DTPA) and SO42− and separated chromatographically. The values of δ18O and δ34S were measured using a continuous‐flow elemental analyzer coupled to an isotope‐ratio mass spectrometer. Results: The δ34S values in BaSO4 precipitated from Na2SO4 solution determined by methods (a)–(c) were consistent within precisions of ±0.5‰. The δ18O values of methods (a) and (b) were consistent within ±0.2‰, whereas the δ18O values of methods (c) and (d) increased with increasing HCl concentrations. Similar results were obtained from samples of atmospheric precipitations. The δ18O values from DTPA‐treated BaSO4 were consistent with those obtained by chromatographic separation within ±0.5‰. Conclusions: We found no significant differences in the effects of various pretreatments (acidification, heating, concentration, and drying) on δ18O and δ34S values in sulfate from samples of atmospheric precipitation and aerosols extracted as BaSO4 if HCl was not added to the sample before heating and BaSO4 was treated with DTPA for the δ18O analysis. [ABSTRACT FROM AUTHOR]

Rationale: Preparation of BaSO 4 from samples of atmospheric rain, snow, and aerosols has been used for δ 18 O and δ 34 S analyses. In the present study, we investigated the effect of various sample pretreatments on δ 18 O and δ 34 S values determined from a Na 2 SO 4 reagent solution and samples of atmospheric precipitation to improve assay time and cost efficiency., Methods: BaSO 4 was prepared from a Na 2 SO 4 solution by (a) evaporative concentration, (b) evaporation to dryness, (c) evaporation to dryness after adding HCl, and (d) evaporation to concentration after adding HCl, followed by cooling and then precipitation using a BaCl 2 solution. To analyze the atmospheric precipitation samples for δ 18 O, BaSO 4 prepared from the samples was treated with diethylenetriaminepentaacetic acid (DTPA) and SO 4 2- and separated chromatographically. The values of δ 18 O and δ 34 S were measured using a continuous-flow elemental analyzer coupled to an isotope-ratio mass spectrometer., Results: The δ 34 S values in BaSO 4 precipitated from Na 2 SO 4 solution determined by methods (a)-(c) were consistent within precisions of ±0.5‰. The δ 18 O values of methods (a) and (b) were consistent within ±0.2‰, whereas the δ 18 O values of methods (c) and (d) increased with increasing HCl concentrations. Similar results were obtained from samples of atmospheric precipitations. The δ 18 O values from DTPA-treated BaSO 4 were consistent with those obtained by chromatographic separation within ±0.5‰., Conclusions: We found no significant differences in the effects of various pretreatments (acidification, heating, concentration, and drying) on δ 18 O and δ 34 S values in sulfate from samples of atmospheric precipitation and aerosols extracted as BaSO 4 if HCl was not added to the sample before heating and BaSO 4 was treated with DTPA for the δ 18 O analysis., (© 2023 John Wiley & Sons Ltd.)