Dear Pier,

Pier De Groot wrote:
>
> Dear Nicolas and others,
>
> I basically agree with your reasoning. Probably the small amount of S
> used is oxidized before it can evaporate and swept out by carrier gas
> and be deposited as native sulfur in cooler parts of the device (if
> not, you have a serious problem).
>
> But one factor worries me ...
> You state that, if taking smaller portions homogenity is a problem.

Nope. I don't.

> [...] So, considering the above reasoning, I do not agree with
> Nicolas' statement that smaller sample create 'problems'

Neither do I.
BTW, this was not my statement.

What I wrote is that homogeneity of smaller samples is a *concern*, i.e.
that one might want to bear in mind the potential grain to grain
variability which can be accessed at these levels.
You can see it as a -limited- problem (how representative are my data
points), or as a nice way to go into further details (as you said,
extended isotope range and such), depending on your interest, or maybe
on how anxious you are?
Be (re)assured I have nothing against the progress of science, and I'm
glad new techniques allow more and more refined types of analysis ;)
I, for instance, really look forward to the coming day we can achieve
reliable isotope measurements on grain by grain or intra-grain aerosol
studies...

One real limitation though might be the homogeneity of solid reference
materials which is not guaranteed at very low levels (this at least
concerns solid material techniques, such as continuous flow EA-IRMS).
I hope this will help relieve at least some of your worries...
Cheers
Nicolas
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