Universität zu Köln

Klipsch, Swea ORCID: 0000-0003-3195-4360, Herwartz, Daniel ORCID: 0000-0003-3604-8295 and Staubwasser, Michael ORCID: 0000-0002-5892-1115 (2021). Optimizing sulfate pyrolysis triple oxygen isotope analysis for samples from desert environments. Rapid Commun. Mass Spectrom., 35 (14). HOBOKEN: WILEY. ISSN 1097-0231

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Abstract

Rationale The triple oxygen isotope composition of sulfate may reveal the formation pathway and depositional sources and may indicate slow biologic cycling in the environment. Pyrolysis mass spectrometry is better suited for large sample workloads during environmental profiling but sufficient precision and a thorough verification of accuracy are required for comparison with higher precision laser fluorination data. Methods Quantitative sulfate extraction from soil samples at neutral pH, purification, conversation into Ag-sulfate, and pyrolysis mass spectrometry were modified for high sample throughput. Samples were analyzed after pyrolysis in quartz cups and gold capsules in a modified EuroVector model 3000 elemental analyzer. Sample O-2 was measured in continuous He-flow after purification by cryo-trapping and chromatography on a Thermo Finnigan MAT253 isotope ratio mass spectrometer. A protocol for routine quality control and data normalization ensures long-term accuracy of the pyrolysis method. Results The 1 sigma SD external reproducibility is 0.12 parts per thousand for Delta O-17(SO4) values on 30 mu mol samples. Careful normalization for a daily analytical session accounts for changing pyrolysis conditions over the course of multiple sessions. The precision and accuracy obtained with quartz cups are comparable with those obtained with gold capsules. Pyrolysis and fluorination data for in-house standards from four laboratories and from an Atacama Desert gypsum-soil profile are identical and demonstrate the accuracy of our simplified method. Conclusions Pyrolysis of sulfate in quartz cups and a modified simple elemental analyzer setup allows for accurate, precise, fast, cost-efficient, and non-hazardous mass spectrometric analysis. Exchangeability of data from pyrolysis and laser fluorination methods was demonstrated by repeat analysis of standards and natural samples despite high contents of interfering, easily soluble nitrates and chlorides.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Klipsch, Swea UNSPECIFIED orcid.org/0000-0003-3195-4360 UNSPECIFIED Herwartz, Daniel UNSPECIFIED orcid.org/0000-0003-3604-8295 UNSPECIFIED Staubwasser, Michael UNSPECIFIED orcid.org/0000-0002-5892-1115 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-565304
DOI:	10.1002/rcm.9102
Journal or Publication Title:	Rapid Commun. Mass Spectrom.
Volume:	35
Number:	14
Date:	2021
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1097-0231
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ATACAMA DESERT; DELTA-O-18; EXCHANGE; O-2; CONSTRAINTS; NITRATE; SULFUR; QUARTZ; SOILS; WATER Multiple languages Biochemical Research Methods; Chemistry, Analytical; Spectroscopy Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56530