The SRM File

The SRM file contains compositional data for standards. To calibrate raw data standards measured during analysis must be in this database.

File Location

The default SRM table is stored in the resources directory within the latools install location.

If you wish to use a different SRM table, the path to the new table must be specified in the configuration file or on a case-by-case basis when calibrating your data.

File Format

The SRM file must be stores as a .csv file (comma separated values). The full default table has the following columns:

Item SRM Value Uncertainty Uncertainty_Type Unit GeoReM_bibcode Reference M g/g g/g_err mol/g mol/g_err
Se NIST610 138.0 42.0 95%CL ug/g GeoReM 5211 Jochum et al 2011 78.96 0.000138 4.2e-05 1.747e-06 5.319e-07

For completeness, the full SRM file contains a lot of info. You don’t need to complete all the columns for a new SRM.

Essential Data

The essential columns that must be included for latools to use a new SRM are:

Item SRM mol/g mol/g_err
Se NIST610 1.747e-06 5.319e-07

Other columns may be left blank, although we recommend at least adding a note as to where the values come from in the Reference column.

Creating/Modifying an SRM File

To create a new table you can either start from scratch (not recommended), or modify a copy of the existing SRM table (recommended).

To get a copy of the existing SRM table, in Python:

import latools as la

la.config.copy_SRM_file('path/to/save/location', config='DEFAULT')

This will create a copy of the default SRM table, and save it to the specified location. You can then modify the copy as necessary.

To use your new SRM database, you can either specify it manually at the start of a new analysis:

import latools as la

eg = la.analyse('data/', srm_file='path/to/srmfile.csv')

Or specify it as part of a configuration, so that latools knows where it is automatically.