Author Topic: Strategies for Improving Accuracy Using Trace Elements Standards  (Read 2233 times)

Mike Jercinovic

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Re: Strategies for Improving Accuracy Using Trace Elements Standards
« Reply #15 on: July 14, 2019, 06:40:00 pm »
Well, hopefully a wt% Or 2 wt.% U is something humans  could measure, but its more about reconciling actininide counts with all those pesky transitions...

Probeman

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Re: Strategies for Improving Accuracy Using Trace Elements Standards
« Reply #16 on: July 14, 2019, 06:55:35 pm »
Well, hopefully a wt% Or 2 wt.% U is something humans  could measure, but its more about reconciling actininide counts with all those pesky transitions...

Well there it is.  We've come full circle.    :-*
 
Yes, well you might be forgiven to think it's something that humans could measure, but as you know it gets pretty difficult when there is inhomogeneity present at the micro scale.  And my understanding from Hanchar was that doping U or Pb in synthetic monazite always produced zoned crystals.  We see the same darn thing when doping Ti in quartz, and I suspect other trace elements in other synthetic crystals.

Hence the rationale for my plea/rant for matrix matched zero blank standards...   at least we know a priori exactly what the concentration is, when the element is not present!   ;D
The only stupid question is the one not asked!

Mike Jercinovic

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Re: Strategies for Improving Accuracy Using Trace Elements Standards
« Reply #17 on: July 14, 2019, 07:15:03 pm »
Sorry, the point here is not really the measurement of uranium in this case, but the influence of the presence of uranium on thorium in particular. That is, measuring zero thorium in a blank with lots of uranium present.. just like measuring zero uranium with a hi Th blank. We do see the occasional monazite with much more uranium than thorium, so just trying to get the acitinides right.

Probeman

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Re: Strategies for Improving Accuracy Using Trace Elements Standards
« Reply #18 on: July 14, 2019, 08:14:13 pm »
Sorry, the point here is not really the measurement of uranium in this case, but the influence of the presence of uranium on thorium in particular. That is, measuring zero thorium in a blank with lots of uranium present.. just like measuring zero uranium with a hi Th blank. We do see the occasional monazite with much more uranium than thorium, so just trying to get the acitinides right.

Ah, I misunderstood. OK that makes sense.

So as you say, for monazite accuracy one really needs *two* blank standards.  One with REEs and Th as a zero blank for the U and Pb measurement. And a second blank standard standard with lots of REEs and U, but with zero Th present.

It's a difficult material. I'm glad you're the one who is working all this out.   ;D   But seriously I'd like a piece of the U and Pb blank synthetic monazite just to test my own efforts.  If you have some available.   :)
« Last Edit: July 14, 2019, 09:21:36 pm by Probeman »
The only stupid question is the one not asked!