87Sr/86Sr DRS?

amzipkin

Hi Bence,

I just found the newer DRS that combines REE interference corrections with CaAr and Rb corrections on Github and installed it. Is any documentation about how to use this DRS (and about what is happening under the hood) available? Either an update to the Iolite4 manual, a Notes blog post, or a YouTube video explainer? Or perhaps your collaborator actually published a peer-reviewed study that uses and validates the new DRS?

Thanks,

Andrew

Bence

amzipkin

Hi Andrew,

This DRS is still a work in progress, but we hope to have it out soon (in the next month or so). We'll include some documentation and references to the original work it's based on when we release it.

More info to come!

-Bence

amzipkin

Aaand just to make things interesting on a Friday, the older Sr isotope DRS (Sr Isotopes Example, which I downloaded fresh from Github today and installed on a new computer) is throwing a novel (to me) error:

There was an error in your python runDRS function: : std::runtime_error: Cannot overwrite an input channel with an intermediate or output channel: Sr87 File "C:/Users/azipkin/Documents/iolite/Plugins/Data reduction schemes/Sr_isotopes.py", line 129, in runDRS data.createTimeSeries(name, data.Intermediate, indexChannel.time(), channel)

Now, unlike my past use of the Sr Isotopes DRS, I am trying to process data generated using an iCAP TQ ICP-MS operating in TQ mass shift mode, not MC-ICP-MS data. This is method development work to assess whether some recent claims of generating reliable 87/86 results on a quad are viable. However, it doesn't appear to be an issue with the type of data that I am loading to Iolite. When I examine the input channels in Iolite, they correctly recognize the pre-shift mass and post-shift mass for those analytes (82Kr, 83Kr, 84Sr, 87Sr, and 88Sr) that underwent an O2 mass shift.

So, any ideas?

Bence

amzipkin

THE CAUSE: Until recently, most Sr isotope data was collected on multi-collector instruments. When iolite would import data from those mass spectrometers, the input channels would mostly have names like 'm87', 'm86' etc. Most quad instruments will name those same channels 'Sr88', 'Sr87' etc.

In the previous version of Sr isotope DRS, the DRS would look for these channels based on mass. Then it would calculate interference corrected channels, one of which would be 'Sr87' (i.e. the Sr87 signal after correcting for the Rb87 interference). When iolite would store the results of this calculation, if there was already an input channel called 'Sr87', it would inadvertently overwrite the input channel. We recently added a check for this happening in iolite v4.5.5, and stopped it from happening (iolite in principle never alters input channels after import). That would be why you're seeing the error.

THE FIX: I have just uploaded an updated version of the Sr isotope DRS to GitHub where those intermediate channels have been renamed to have '_c' added to their name. So, for example, the calculated Sr87 channel is now 'Sr87_c' otherwise, everything else is the same for that DRS.

I hope that helps. If you still have any troubles after updating your copy of the DRS, please let us know.

-Bence

amzipkin

Thanks for the quick fix Bence. The updated version of the Sr Isotopes DRS works with my triple quad ICP-MS data and I see the _c suffix on the intermediate channels.

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