May 2010


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Malcolm S Pringle <[log in to unmask]>
Reply To:
JEOL-Focused Probe Users List <[log in to unmask]>
Wed, 26 May 2010 12:12:59 -0400
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Electron Microprobe Lab, University of Minnesota

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Ellery --

Sobolev et al (Science, 2007) report 140 ppm Co for SCO USNM 111312/444 
by Laser
ablation ICP-MS.  They then use that value for SCO to calibrate Co in their
massive olivine study; they also measured 3 SCO's every 30-50 points as an
internal drift and accuracy check.

Their preferred EMP operating conditions were 20 kV & 300 nA (!) with 120 sec
counting times on the Max-Planck Jeol Jxa 8200.

Also, they determined a correction for the FeK second order shoulder 
on Co K
by analyzing Fe bearing standards free of Co:

CoOc = CoOm - 0.0011~FeOm - 0.013.

Its not clear to me whether that correction would be ~ universal, or 
need to be
determined for your particular machine.

They also report "the above measurement conditions routinely yield detection
limits of around 6-15 ppm based on 3 sigma criteria by Jeol standard software,
and errors of 15-30 ppm for trace elements and 0.01 mol% for Fo content (2
standard errors) established by counting statistics and reproducibility of
olivine standard (see Fig S1-S2)."  Co & Mn precision, LA-ICP MS vs EMP, are
specifically compared in Fig S3.

Here's the link to the online supplement:

There is a massive amount of data there!

-- Malcolm

If you don't feed the teachers, they will eat the children.
Anonymous teacher, told to Linda Albert, Cooperative Discipline, 1996.
But none of that will transform education if we fail to cherish --
and challenge -- the human heart that is the source of good teaching.
Parker J Palmer, The Courage to Teach, 1998.
Malcolm S Pringle, Dept. of Earth, Atmospheric, and Planetary Sciences
Massachusetts Inst of Technology, 77 Massachusetts Ave    Bldg 54-1210
Cambridge, MA    02139-4307 USA                    Cell:  617-319-6584