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Rapid and high‐resolution stable isotopic measurement of biogenic accretionary carbonate using an online CO 2 laser ablation system: Standardization of the analytical protocol
Author(s) -
Sreemany Arpita,
Bera Melinda Kumar,
Sarkar Anindya
Publication year - 2017
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7992
Subject(s) - chemistry , aragonite , mass spectrometry , isotope ratio mass spectrometry , analytical chemistry (journal) , laser ablation , isotope , matrix (chemical analysis) , stable isotope ratio , isotope analysis , carbonate , laser , calcite , mineralogy , chromatography , geology , optics , oceanography , physics , organic chemistry , quantum mechanics
Rationale The elaborate sampling and analytical protocol associated with conventional dual‐inlet isotope ratio mass spectrometry has long hindered high‐resolution climate studies from biogenic accretionary carbonates. Laser‐based on‐line systems, in comparison, produce rapid data, but suffer from unresolvable matrix effects. It is, therefore, necessary to resolve these matrix effects to take advantage of the automated laser‐based method. Methods Two marine bivalve shells (one aragonite and one calcite) and one fish otolith (aragonite) were first analysed using a CO 2 laser ablation system attached to a continuous flow isotope ratio mass spectrometer under different experimental conditions (different laser power, sample untreated vs vacuum roasted). The shells and the otolith were then micro‐drilled and the isotopic compositions of the powders were measured in a dual‐inlet isotope ratio mass spectrometer following the conventional acid digestion method. Results The vacuum‐roasted samples (both aragonite and calcite) produced mean isotopic ratios (with a reproducibility of ±0.2 ‰ for both δ 18 O and δ 13 C values) almost identical to the values obtained using the conventional acid digestion method. As the isotopic ratio of the acid digested samples fall within the analytical precision (±0.2 ‰) of the laser ablation system, this suggests the usefulness of the method for studying the biogenic accretionary carbonate matrix. Conclusions When using laser‐based continuous flow isotope ratio mass spectrometry for the high‐resolution isotopic measurements of biogenic carbonates, the employment of a vacuum‐roasting step will reduce the matrix effect. This method will be of immense help to geologists and sclerochronologists in exploring short‐term changes in climatic parameters (e.g. seasonality) in geological times.