Sr Saturn

Sr Saturn and TE Saturn

Sr Saturn and TE Saturn are open-source, Python-based freeware programs designed for rapid and user-friendly reduction of strontium isotope and trace element data obtained from LA-ICP-MS. Unlike software such as Iolite and Glitter, which support a broad range of isotopic analyses, Sr Saturn and TE Saturn are specifically tailored to strontium isotopes and trace elements, providing a focused environment to streamline data processing. The tools support ICP-MS data from Agilent, Thermo Fisher Element II, and Neptune Plus instruments.

  • Data Processing Features:
    • Automatic and interactive integration of time-resolved background and sample signals.
    • Calibration and correction of Sr-isotope ratios.
    • Trace element calibration methods based on standards (e.g., Longerich et al., 1996).
    • Polynomial method for sensitivity drift correction (Cheatham et al., 1993).
    • Manageable external standard database for reference materials.
    • Ability to create publication-ready ternary, scatter, and line plots.
  • User Interface:
    • Main Window: Displays imported files, standard and sample tables, accessible functions, and calculation results.
    • Time Review Window: Allows time-integration for each spot and manual adjustment of signal/background areas.
    • Plot Window (TE Saturn): Generates spider, scatter, ternary, and deviation plots.
  • Accessibility:
    • Available for download on AIR website with user documentation.
    • Source code accessible on GitHub, allowing customization and modifications.

Sr Isotope Data Reduction Procedures in Sr Saturn

Reference Material Bracketing: External correction factor derived by comparing mass bias-corrected Sr ratios in reference materials and applied to unknowns for added accuracy.

Interface Elements

  1. Left Sidebar Menu:
    • This includes various options like:
      • Home: Main navigation.
      • See Reduction: Likely displays the current data reduction process.
      • Load Data: For importing datasets.
      • Add Data: To input new data entries.
      • Open Project / Save Project: Project management options.
      • Export Data: To output reduced data.
      • Time Series: Likely allows time-resolved signal review.
      • Run History: Possibly stores historical data processing runs.
      • Optional Corrections: Where users may apply specific correction methods.
      • Settings: General software configuration.
  2. Standard and Sample Data Tables:
    • Standards and Samples sections display the strontium isotope ratios with detailed measurements.
    • Key columns in each table include:
      • 87Sr/86Sr (i): Shows initial 87Sr/86Sr ratios for standards and samples.
      • ± 2 S.E.: Represents the precision in 87Sr/86Sr measurements (standard error).
      • Additional columns likely contain other ratios like 84Sr/86Sr and respective uncertainties.
  3. Project Panel:
    • Located at the top-right, displaying the name of the current project (e.g., “Unknown Project”).
  4. Central Data Display:
    • The central area shows lists of standards and samples with the corresponding strontium isotope ratios, uncertainties, and other calculated values.

Functionality Overview

  • Data Reduction: Users can observe, calculate, and correct isotope ratios for Sr in a clear, organized table.
  • User-Friendly Navigation: The sidebar allows for intuitive project management, loading and saving data, and adjusting optional correction parameters.
  • Error Display: The inclusion of standard errors (± 2 S.E.) for each isotope ratio ensures precision tracking in isotope analysis.

The Signal Review window within the Sr Saturn software. Here users can review and adjust signal parameters for strontium isotope data processing.

Components

  1. Setup Limits (All Dataset and Current Data):
    • Cycle Number / Percentage Options: Allows users to define the background and signal regions based on either cycle number or percentage of the dataset.
    • Background and Signal Limits: Users can specify the start and end points for background and signal regions. For example, “Background start (+)” and “Signal end (-)” fields let users fine-tune the integration window.
    • Apply and Restore: These buttons allow users to apply changes to the signal integration limits or restore to default settings.
  2. Data Resource:
    • Options to select Reference Material, Samples, Raw Data, or Ratios. This determines which type of data is displayed and analyzed.
    • Label Plotted: Allows selection of a specific isotope ratio (e.g., 86Sr) for plotting in the signal review graph.
  3. Run Name:
    • A list of run names is displayed for easy access, with the current active run highlighted (e.g., “001Sr”).
  4. Signal Graph (Top Right):
    • Displays the intensity (Y-axis) over cycle (X-axis) for the selected sample or standard.
    • Marked Background Region and Signal Region are defined by colored vertical lines, allowing visual adjustment of the integration areas.
    • Users can observe the transition between background and signal regions and ensure that the integration limits are appropriately set for accurate analysis.
  5. Ratio Plots (Bottom):
    • Multiple plots show calculated isotope ratios with their respective error margins (e.g., 87Sr/86Sr, 84Sr/86Sr).
    • Error bars indicate the precision of each ratio measurement.
    • Green lines possibly represent the accepted values or mean for each ratio, providing a visual guide for evaluating the data quality.

Functional Highlights

  • Interactive Signal Adjustment: The interface allows manual adjustment of background and signal limits, ensuring accurate time-resolved integration for each analysis.
  • Data Resource Selection: Flexibility to review different data types (ratios, raw data) and apply specific corrections or calibrations.
  • Precision Display: Ratio plots with error margins aid in monitoring the consistency and reliability of the isotope ratios across different cycles.

Isobaric Interference Corrections:

Kr Interference: Addressed by gas blank measurements (“on-peak-zeros”) and subtraction from raw signals.

Rb Overlap on 87 Sr: Sr-isotope targets should ideally have low Rb/Sr ratios (<0.002); however, correction is possible up to a ratio of 0.2 by using peak stripping and calculating Rb interference.

Er 2+ and Yb 2+: Doubly charged REEs interfere with Sr isotope masses. These interferences are corrected by measuring half-masses, allowing peak stripping using an Er or Yb mass bias.

Ca Molecular Interferences: Potential interferences from Ca molecules are minimized through calibration using primary reference material bracketing.

Data Reduction Workflow:

Raw Data Processing: Offline reduction of raw signals (beam intensities, on-peak baselines) via Sr Saturn software.

Stepwise Correction:

Subtract Kr interferences using on-peak baselines.

Calculate Yb mass bias and apply it for Yb 2+ and Er 2+ corrections.

Correct Sr mass bias for 86 Sr and 88 Sr to address Rb interference on 87 Sr.

Calculating Final Ratios: Interference-free Sr ratios are calculated and corrected to 86 Sr/88 Sr = 0.1194.

Outlier Removal: Values beyond 2 S.D. are excluded; average Sr isotope value per spot is computed.

External Correction: