DeterminationofNa,Mg, P, K, Ca, Cr,Mn, Fe, Cu, Zn, Se, andMoby ICP-MS
F.
PROCEDURE
1.
SamplePreparation:microwavedigestion
a)
Samples arepreparedat least induplicate. Invessels,weigh samples to thenearest 0.0001g. Add0.5mLof
the5mg/LGe/Temultielement internal standard solution (digital pipet), 5mLof nitric acid, and2mLof
hydrogenperoxide.
b)
Seal vessels,withventingnuts and caps, andplaceon turntable for digestion.
c)
Place the turntable inMARS5 (CEMCorp.Matthews,NC, USA)microwaveoven forone stepnitric/hydrogen
peroxidedigestion. Seedigestionparameters in section D.5above.
d)
At theendof themicrowave coolingperiod, placevessels inahood. Unscrew the cap slowly togradually
release thepressure.
e)
Carefully removeventingnut (small amount of gaseswill escape) and carefully rinse ventingnut so that the
rinseate falls into their correspondingvessels.
f)
Addapproximately20mLof labwater to the contentsof thevessel and transfer intoa50mL samplevial.
Rinse vessel and transfer rinseate into the samplevial. Add0.5mLmethanol to samplevial anddilute to
approximately50mLwith laboratorywater. The final volumedoesnot need tobequantitativebecause
internal standardswereaddedprior todigestion, therefore, theanalyte/internal standard ratioswill be
constant.
2.
Agilent 7500x ICP-MSOperation (instrument in standbymodeandautosampler turnedon)
a)
Start theMassHunter softwarebydouble clickingon its icon, ICP-MSTop, locatedon thedesktop. Select
Instrument>>InstrumentControl.
b)
Select
Plasma>>PlasmaOn
. Clickyes. Thegases for theplasma torchare switchedonand thegas linesare
purged. Theplasma ignitesand the interface rotarypump starts toevacuate the interfacevacuum chamber.
Once the vacuum reaches4.5 x10
2
Pa the titlebarwill indicate that the instrument has changed from the
Standby toAnalysismode. Theplasmaonandoff icons are shown in the figurebelow.
MTE-02
FORWORKINGGROUP/ERPUSEONLY
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