Abstract:
LIMS for Light Stable Isotopes is a Microsoft Access database program for managing samples, analyses, reports, and other data in a stable isotope (and tritium, carbon-14, and chlorofluorocarbon) laboratory.
The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio
... analyses of samples, (iii) calculate analytical results using standardized algorithms stored in the database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Major benefits of this system include (i) a dramatic improvement in quality assurance, (ii) an increase in laboratory efficiency, (iii) reduction in workload due to the elimination or reduction of the retyping of data by laboratory personnel, and (iv) a decrease in errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and it provides a record of what correction factors have been used through time. It provides an audit trail for laboratories.
LIMS for Light Stable Isotopes can store information about samples and analytical results for the following isotope ratios, isotopes, and chlorofluorocarbons:
2H/1H 11B/10B 18O/16O 37Cl/35Cl 129Xe/132Xe
3H 13C/12C 21Ne/20Ne 38Ar/36Ar 136Xe/132Xe
3He 14C 22Ne/20Ne 40Ar/36Ar CFC-11
4He 15N/14N 30Si/28Si 83Kr/84Kr CFC-12
7Li/6Li 17O/16O 34S/32S 86Kr/84Kr CFC-113
LIMS for Light Stable Isotopes has proven useful in laboratories that (i) receive samples for isotopic analysis from numerous individuals, and (ii) perform at least a few thousand isotopic analyses per year. Users who do not meet at least one, and likely both these criteria, will probably not find worthwhile the investment in time that it takes to learn and fully apply LIMS for Light Stable Isotopes.
Experience has shown that approximately one week is required to become reasonably acquainted with LIMS for Light Stable Isotopes and to set it up for operation in a laboratory. The user should plan one day for the tutorial in the manual and three to four days to set up a new database and begin importing isotopic analyses from mass spectrometers in the laboratory. Although this may seem like a large investment in time, the rewards in increased productivity and better organization in a laboratory far outweigh this setup cost.
Numerous improvements were made for continuous flow isotopic analysis in versions 7.13 (for Microsoft Access 97) and 8.13 (for Microsoft Access 2000). It is much easier to import isotopic results from Finnigan ISODAT worksheets, even worksheets on which corrections for amount of sample (linearity corrections) have been added. The capability to determine blank corrections using isotope mass balance from analyses of elemental analyzer samples has been added. It is now possible to calculate and apply drift corrections to isotopic data based on the time of day of analysis. Whereas Finnigan ISODAT software is confined to using only a single peak for calculating delta values, LIMS now enables one to use the mean of two or more reference injections during a continuous flow analysis to calculate delta values. This is useful with Finnigan's GasBench II online sample preparation system. Concentrations of carbon, nitrogen, and sulfur can be calculated based on one or more isotopic reference materials analyzed with a group of samples. Both sample data and isotopic analysis data can now be exported to Excel files. A calculator for determining the amount of sample needed for isotopic analysis based on a previous amount of sample and continuous flow area is now an integral part of LIMS for Light Stable Isotopes. LIMS for Light Stable Isotopes can now assign an error code to Finnigan elemental analyzer analyses in which one of the electrometers has saturated due to analysis of too much sample material, giving rise to incorrect isotopic abundances.
[Summary provided by the USGS.] 
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