RESUMEN
RATIONALE: Clumped isotope analyses (Δ47 ) of carbonates by dual inlet (DI) mass spectrometry require long integration times to reach the necessary high precision due to the low abundance of the rare isotopologue 13 C18 O16 O. Traditional DI protocols reach this only with large amounts of sample and/or a large number of replicates as a large portion of the analyte gas is wasted. We tested an improved analytical workflow that significantly reduces the sample sizes and total analysis time per sample while preserving precision and accuracy. METHODS: We implemented the LIDI (long-integration dual-inlet) protocol to measure carbonates in micro-volume mode using a Kiel IV carbonate device coupled to a Thermo Scientific 253 Plus isotope ratio mass spectrometer without the new 1013 ohm amplifier technology. The LIDI protocol includes a single measurement of the sample gas (600 s integration) followed by a single measurement of the working gas (WG) with the same integration time. RESULTS: The Δ47 measurements of four calcite standards over a period of 5 weeks demonstrate excellent long-term stability with a standard deviation of ±0.021 to ±0.025 for the final values of the individual aliquots. The Δ47 analyses of a coral, four foraminifera and a calcite precipitated in the laboratory demonstrate that 14 replicates of 90 to 120 µg are sufficient to achieve an external precision of ±0.007 (1SE) or of ±0.013 at the 95% confidence level. CONCLUSIONS: This study demonstrates that by using a Kiel IV-253 Plus system with LIDI it is possible to achieve the same analytical precision as conventional DI measurements with at least a factor of 40 less sample material. With the new 1013 ohm resistor technology there is the potential to reduce the required sample material even more. This opens new avenues of research in paleoceanography, paleoclimatology, low-temperature diagenesis and other currently sample size limited applications. Copyright © 2017 John Wiley & Sons, Ltd.
RESUMEN
RATIONALE: The measurement of complex isotope systems, notably the multiply substituted isotopologues of CO2 derived from carbonates, is challenging from a mass spectrometric point of view, but it is also time consuming and difficult from a data reduction and normalization perspective. Dedicated software often lags behind and currently limits fast, reliable and reproducible data analysis and inter-laboratory reproducibility. METHODS: We have developed new community software 'Easotope' using Java and the Eclipse framework. The objectives were to reduce and normalize complex isotopic data easily using a program that could run on multiple platforms, with a central database to store data and constants, an open architecture giving end users a complete view of the data processing steps, and a permissions system allowing the administrator to empower each user in proportion to their expertise. RESULTS: Easotope is now freely available to download, and comprises both a server and a client executable. The server can be run either on a remote machine accessible via the internet, or on a localhost. The client allows users to access the server, and to enter and manipulate data. Easotope currently supports full data storage, data processing and data normalization for bulk isotopes of carbon and oxygen, and for clumped isotopes. CONCLUSIONS: Easotope greatly simplifies data processing, reducing processing time to less than a second compared with 30 min when done manually. The software also ensures consistency in data reduction and normalization both within a laboratory and between laboratories. Easotope is designed with the ability to implement other isotopic systems in the future. Copyright © 2016 John Wiley & Sons, Ltd.
