Sr Standards (CaAr DRS) and Adding New Standards

kortega

Hello,
I'm trying to process a Sr analysis using the CaAr DRS, but I was a little bit confused about how the standards work. My samples include (1) an in-house standard for which the 87/86 Sr ratio is known, (2) Nano Sr, and (3) a sample of something we're hoping to use as a standard once we confirm the 87/86 Sr ratio on our instrument. When I try to crunch the data, the DRS returns an error that "Ref Materials must be used," but the reference materials I see listed in Iolite v4 aren't necessarily 87/86 standards. I suppose my question is: how can I add a new standard reference material for the Sr CaAr DRS (presumably the Nano Sr?), does this standard need anything other than an 87/86 Sr ratio to work with the CaAr DRS, and do I have some misunderstanding of how the correction works? I was looking through the user guides and forum but couldn't quite figure out (or simply missed) the answer to this/where my misunderstanding begins.
Thank you (again)!

VitorBarrote

Hey Kortega,

According to this part of the DRS

 `# Now check if there are selections for the reference standard, and if so, generate standard-normalised ratios
    try:
        StdSpline_Sr87_86 = data.spline(rmName, "Sr8786_Corr").data()
        StdValue_Sr87_86 = data.referenceMaterialData(rmName)["87Sr/86Sr"].value()
    except:
        IoLog.error("The Combined Sr DRS requires Ref Material selections to proceed.")
        drs.message("DRS did not finish. Please check Messages")
        drs.progress(100)
        drs.finished()
        return

    StdCorr_Sr8786 = Sr8786_Corr * StdValue_Sr87_86 / StdSpline_Sr87_86

    # Now generate age-corrected values (using the observed Rb/Sr ratio)
    # NOTE: The line below used Sr8786_Corr. Changed to use
    # Std Corrected data (BP, 2021-02-01)
    Sr8786_AgeCorr = StdCorr_Sr8786 - (Rb87Sr86_Corr * (0.000013972 ** Age) - 1)

    try:
        StdSpline_Sr8786_b = data.spline(rmName, "Sr8786_Corr_b").data()
    except:
        IoLog.error("The Combined Sr DRS requires Ref Material selections to proceed.")
        drs.message("DRS did not finish. Please check Messages")
        drs.progress(100)
        drs.finished()`

All you are correcting to is the 87Sr/86Sr so all you need is a Reference Material with a value for 87Sr/86Sr. Please note the format, as the DRS will search for this exact label on your RefMat file.

To add a new RefMat you can go to the Reference Materials tab and click on the + and select blank to create a completely new entry. I think that the Iolite Basics workshop goes through that. Check it out.

https://www.youtube.com/watch?v=YV9RUqzTHhM&t=1505s&ab_channel=IoliteSoftware

Also this has been covered in another post:
https://forum.iolite.xyz/d/171-how-to-add-a-new-reference-material

VitorBarrote

This one might also be helpful? https://forum.iolite.xyz/d/111-87sr86sr-drs

amzipkin

Hi folks,

I was running the CaAr DRS for the last couple of years and initially had the same question, among others (see the last thread linked to by Vitor). What I did to add NanoAr was go to Data-->Reference Materials-->CaCO3 and copy the entry for C_MMC (modern marine carbonate) using the copy button at the top right. I then renamed the new entry to NanoSr and replaced the copied 87Sr/86Sr value with the applicable value from Weber's publication on NanoSr. By copying the entry from MMC, the new entry automatically falls under the carbonate reference materials category. Hope that helps!

Andrew