Create an Analysis Method Template

1 Read Data

Click “Approach” and then “Preview” or “New” to open the analysis method template editor.

First, click “New” and enter the name for the new analysis method.

2 “Formula” module

The “Raw Data” section displays the ids and names of the data to be analyzed and the corresponding column names in the raw data. Note: “r_01, r_02, r_x” serve as ids for corresponding isotopes, which will be used in subsequent formula editing.

Checking the checkboxes under “Bkg Subtraction” to enable background subtraction. The background subtraction principle in the “Plume” software is as follows: first, select the background signal range using “Background”, then remove outlier data within the background range based on 2SD, and the remaining data is averaged to obtain the “background value”, which will be subtracted from the raw data.

In the “Formula” section, you can edit formulas, including addition, subtraction, multiplication, division, exponentiation, etc. As shown in the following figure, “f1” refers to a formula id used for calculations. “Name” indicates the actual name of the formula, which is not used for calculations but is displayed as the formula name in subsequent charts. Enter the specific formula in “Expression.”

 You can set constant parameters to record commonly used constants in “Constants”, but they must be numerical values, not formulas.

Note: Calculations in the “Formula” section are performed on each “cycle” of data (the smallest data unit), providing an average and relative standard deviation (2SE).

Supported Operators in “Formula”:

• Addition: “+”
• Subtraction: “-“
• Multiplication: “*”
• Division: “/”
• Exponentiation: “^”
• Natural logarithm: “ln()”

“Plume” provides a special constant calculation mode called “Average parameter”. This module allows to input a calculation formula to obtain a constant. For instance, in Hf isotope analysis, you can input the formula for calculating the Hf isotope fractionation factor, and the module will return an average value for that factor. Users can choose to use the average fractionation factor for mass fractionation correction or use it in “Formula” for one-to-one mass fractionation correction.

Another scenario is using the “Average parameter” function to apply a correction parameter calculated from a reference material to the actual analysis sample data. For example, to correct Rb interference on Sr isotopes, analyze a reference material containing only Rb before analyzing the actual sample. By calculating the Rb isotope fractionation factor from this reference material, you can then apply this factor to the actual samples. This function only requires selecting the desired “Reference” name (e.g., NIST610) in “Average parameter.” It indicates that in this data processing, the constant “a1” is calculated from all selected NIST610 samples. This constant can then be used in “Formula.”

In the “Formula” module, each formula has a checkbox next to it indicating “mean”, “2SE” (average standard deviation), and “count” (number of data points involved in the calculation). Checking it means that this data will be included in the subsequent “Export” output.

3 “Normalization” module

The “Normalization” module is used for external calibration. External calibration requires accurate sample names. There is a reference material data file named “ReferenceData.exp” located in (C:\Plume\config). Users can add the necessary reference material names to this database, along with the corresponding isotope names and accurate isotope ratios.

In the “Normalization” section, under any entry’s “Reference”, you can find the names of existing reference materials in the database and select (multiple selections are allowed) the required reference materials.

Choose the isotope ratio of the reference material under any entry’s “Reference Isotope”. Then, select the name of the formula written in the “Formula” module for the current analysis in “Measured Data”. The configuration in the following figure calibrates the measured value of ⁸⁷SrF/⁸⁶SrF using the reference value of ⁸⁷SrF/⁸⁶SrF from the reference material.

After selecting the reference material and the isotope ratio to be calibrated, you can choose a calibration scheme at the bottom:

No Correction: No external calibration will be carried out.

Mean Correction: Using the preceding and following reference materials to calculate the calibration factor, and the average of this factor is used to calibrate the unknown samples.

Interpolation Correction: The average values of the preceding and following reference materials are calculated separately, assuming that the isotope fractionation changes linearly between the two reference materials. The calibration factor for each unknown sample is calculated by linear interpolation.

Delta Calculation: After selecting “Mean Correction” or “Interpolation Correction”, you can choose whether to calculate the Delta value.

4 “Export” Module

In the “Export” module, you can select the data from the “Formula” to export. By selecting “Add all”, all data checked in the “mean” column of “Formula” will be listed. This data can be exported into a file in “Workspace”, whose name can be edited in the dialog of “Export Name”.

You can format a report output template in “New Template”. The following steps need to be taken to formulate the output:

• Edit “Export Name”.
• In the “Order” column, set the data to be output and arrange their order. As shown in the following figure, the data to be output, such as “⁸⁷Sr/⁸⁶Sr”、“2SE”、“⁸⁴Sr/⁸⁶Sr”、“Rb/Sr” should be numbered in the order of 1, 2, 3, etc.

• Click “New Template” and set a name for the template.

• An Excel file will automatically open, which has different sheets already set up, including “Front Cover”, “Back Cover”, and “Data”. Users can design document formats as needed in the different sheets.
• After saving and closing the Excel file, the template is successfully created and saved in the “Plume\template” folder. The use of this template will be introduced in the data report section.