The double spike toolbox


Image by Dennis Mojado

Double spiking is a powerful way to correct for instrumental mass fractionation in mass spectrometry. One of the difficulties of the technique is choosing the double spike composition: by careful choice of the double spike composition, more precise measurements can be made. The aim of the double spike toolbox is to make this choice easier. The toolbox is a collection of codes for performing double spike inversions and optimising double spike compositions for all isotope systems. The workings of the toolbox are described in detail in the following manuscript:

Rudge J.F., Reynolds B.C., Bourdon B. The double spike toolbox (2009) Chem. Geol. 265:420-431 doi:10.1016/j.chemgeo.2009.05.010 [PDF Final] [PDF preprint]

The toolbox is available for python and MATLAB. New users are encouraged to use the python version.


The python package can be simply installed with pip:

pip install doublespike

A brief tutorial is available as a Jupyter python notebook, with additional examples here.

The source code is on github.

The python version of the toolbox can be used directly in a web browser e.g. with Binder or Google Colab. Before use in Colab the package must be installed with !pip install doublespike.


A recent version of MATLAB is required (it has been tested on MATLAB 7.1 (R14SP3) through to MATLAB 9.11 (R2021b)). The Optimization and Statistics toolboxes are also required.

Software download: github

Installation instructions:

  1. Download and uncompress the package.

  2. Add the doublespike folder to MATLAB’s path. (Using MATLAB’s menu: File->;Set Path ->; Add Folder.)

  3. Type ‘doc doublespike’ to view a brief tutorial (also available here) or ‘help doublespike’ for a list of commands.

Double spike cocktail lists

For the impatient, there are lists of optimal double spikes for all isotope systems available here (Excel spreadsheet). These were produced using the double spike toolbox, with some sensible choices of default parameters. See the manuscript for more details. Like all good recipies, they should be taken with a pinch of salt.

For a practical introduction to the double spike technique, I thoroughly recommend the following article:

Klaver, M. and Coath, C.D. Obtaining Accurate Isotopic Compositions with the Double Spike Technique: Practical Considerations. (2019) Geostand. Geoanal. Res. 43: 5-22. doi:10.1111/ggr.12248

A Jupyter python notebook illustrates the use of the toolbox in calculating some of the figures from this paper.

Please send any bug reports or suggestions for improvement to