Anion-Specific Sulfur Isotope Analysis by Liquid Chromatography Coupled to Multicollector ICPMS

Abstract

An accurate method has been developed to measure, in a single analytical run, δ 34 S in sulfite, sulfate and thio-sulfate in water samples by liquid chromatography combined with multicollector inductively coupled plasma mass spec-trometry (MC-ICPMS). The method is based on the anionic exchange separation of sulfur species prior to their online isotope ratio determination by MC-ICPMS. Mass bias correction was accomplished by a novel approach based on the addition of an internal sulfur-containing standard to the sample. This innovative approach was compared to the sample-standard bracketing procedure. On-column isotopic fractionation was observed and therefore corrected by external calibration. Isotopic ratios were calculated by linear regression slope (LRS), an advantageous method for transient signals, leading to a combined uncertainty of δ 34 S below 0.25‰ and a reproducibility below 0.5‰ for the injection of 1 µg of S. The method was successfully applied to the measurement of δ 34 S in synthetic solutions and environmental water samples. Matrix effects leading to δ 34 S overestimation were observed for sulfate in some samples with high sodium/sulfate mass ratios. The developed analytical procedure simplifies the δ 34 S analysis of liquid environmental samples since preparation steps are no longer required and allows the analysis of several sulfur-containing species in a single run.

Simultaneous Compound-Specific Analysis of δ33S and δ34S in Organic Compounds by GC-MC-ICPMS Using Medium- and Low-Mass-Resolution Modes

“…During the last 15 years, multiple-collector inductively coupled plasma mass spectrometry (MC-ICPMS) has been developed and mainly used for sulfur isotope analysis of inorganic compounds. Although MC-ICPMS does not allow precise δ 36 S analysis due to interference by 36 Ar + , analytical precisions similar to IRMS methods have been achieved for δ 33 S and δ 34 S in bulk inorganic material in samples containing only a few nanomoles. − Another study demonstrated that precise (σ < 0.3 mUr) δ 34 S analysis in individual S-containing anions is feasible by coupling ion chromatography with MC-ICPMS. , This method is based on the online separation of anionic species prior to their isotope analysis by MC-ICPMS. Thus, it significantly simplified the sample preparation and additionally allowed for the analysis of several sulfur-containing species as transient signals in a single run.…”

“…19−23 Another study demonstrated that precise (σ < 0.3 mUr) δ 34 S analysis in individual S-containing anions is feasible by coupling ion chromatography with MC-ICPMS. 24,25 This method is based on the online separation of anionic species prior to their isotope analysis by MC-ICPMS. Thus, it significantly simplified the sample preparation and additionally allowed for the analysis of several sulfur-containing species as transient signals in a single run.…”

Isotopic measurements using ICP-MS: a tutorial review

“…89 Interest in Hg is also growing because of the mass-dependent and mass-independent fractionation effects observed in the environment. 90 Other elements of interest include Nd 91 for geochemical dating purposes, B 92,93 for paleoclimate reconstruction, S 94 for source investigations, and Fe, Zn, Cu and Ca in human samples. 95 This last application field studies isotopic fractionation in humans as diagnostic tools in the detection of diseases.…”

Data processing made easy: standalone tool for automated calculation of isotope ratio from transient signals – IsoCor

“…The hyphenated systems introduce the possibility to analyse several species within one run, drastically decrease analysis time, increase sample throughput, and minimize "human error". 3,10 However, the main limitation of on-line isotope analysis with hyphenated systems is the decrease of the precision due to generation of short transient signals. 11 There are several reasons that cause the decrease in precision: (i) transient signals occur in a certain time window of several seconds, thus the total measurement time as well as the commonly applied integration time are considerably lower compared to a continuous sample introduction of several minutes, (ii) the transient signals comprise peak shapes with substantial variations in intensity, thus the weights of points are not equal, (iii) depending on the separation technique, the injected amount of sample might be signicantly lower than the amount of sample processed with off-line separation, thus the signal intensity of the respective isotopes are generally low with hyphenated systems.…”