Application of an improved ion exchange technique for the measurement of δ34S values from microgram quantities of sulfur by MC-ICPMS

Abstract

Motivated by limitations of the existing solution-based Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) studies to low sulfur concentrations, analytical procedures are reported for δ³⁴S measurements (2σ precision of 0.24–0.34‰) at sulfur concentration [S] of 2 μg mL⁻¹, following its purification by anion exchange resin (AER). δ³⁴S values of International Atomic Energy Agency (IAEA) standards S-1, S-2 and S-3, and IAPSO seawater measured in this study agree (within uncertainties) with the consensus values measured by conventional techniques. These values also are in close agreement with the reported numbers by an MC-ICPMS study in which δ³⁴S was measured at [S] of 20 μg mL⁻¹ following its purification by cation exchange resin (CER). Anion exchange purification offers significant advantages of less sample requirement (2 μg S vs. 500 μg S), lower procedural blanks (∼12 ng vs. ∼250 ng of S), and less chemical requirements and sample processing times, over the cation exchange; therefore, δ³⁴S measurements attempted in this study would suffer significantly from procedural blank if CER is used. It is believed that the procedures reported in this study would establish the application of MC-ICPMS to δ³⁴S measurements in low sulfur containing samples, and should find widespread application especially in studies related to glacier, snow, rainwater and aerosol samples.