(
h
)
Potassiumstandardsolution
.—10000mg/L(Merck).
(
i
)
Sodiumstandard solution
.—10000mg/L (Merck).
(
j
)
Magnesiumstandardsolution
.—10000mg/L(Merck).
(
k
)
Phosphorus standard solution
.—10000mg/L(Merck).
(
l
)
Iron standard solution
.—1000mg/L (Merck).
(
m
)
Zinc standard solution
—1000mg/L (Merck).
(
n
)
Copper standard solution
.—1000mg/L (Merck).
(
o
)
Manganese standard solution
.—1000mg/L (Merck).
(
p
)
Indiumstandard solution
.—1000mg/L (Merck).
(
q
)
Chromiumstandard solution
.—1000mg/L (Merck).
(
r
)
Strontiumstandard solution
.—1000mg/L (Merck).
(
s
)
Yttriumstandard solution
.—1000mg/L (Merck).
(
t
)
Cesiumchloride
.—Analytical grade (Merck).
Preparationof ReagentsandStandardSolutions
(
a
)
Stock standard solution
.—Working standards were
preparedfromaCPImultistandardcommercial stockstandard
solution.
(
b
)
Working standard solutions
.—Standards prepared
from stock standard solution are designed to have the same
acid concentration as digested test solutions (i.e., 10% v/v
using sub-boiled or analytical gradeHNO
3
(SLV andMD1)
or 15%v/v (MD2) using combined acids (HNO
3
, H
2
O
2
, and
HCl). (
1
)
Std6
.—Pipet 3.2mL stock standard solution into a
100mLacid-washedvolumetric flask. Add10mLanalytical
gradeHNO
3
(SLV,MD1) or 15mLcombined acids (MD2),
dilute to volumewithH
2
O, mix, and transfer to acid-washed
polyethylene bottle. (
2
)
Std5
.—Pipet 1.6 mL stock standard
solution into a 100 mL acid-washed volumetric flask. Add
10 mL analytical grade HNO
3
(SLV, MD1) or 15 mL
combined acids (MD2), dilute tovolumewithH
2
O,mix, and
transfer to acid-washed polyethylene bottle. (
3
)
Std4
.—Pipet
0.8 mL stock standard solution into a 100 mL acid-washed
volumetric flask. Add 10 mL analytical grade HNO
3
(SLV,
MD1)or15mLcombinedacids(MD2),dilutetovolumewith
H
2
O, mix, and transfer to acid-washed polyethylene bottle.
(
4
)
Std3
.—Pipet0.4mLstockstandardsolutionintoa100mL
acid-washed volumetric flask. Add 10 mL analytical grade
HNO
3
(SLV,MD1) or 15mLcombined acids (MD2), dilute
to volume with H
2
O, mix, and transfer to acid-washed
polyethylene bottle. (
5
)
Std2
.—Pipet 0.2 mL stock standard
solution into a 100 mL acid-washed volumetric flask. Add
10 mL analytical grade HNO
3
(SLV, MD1) or 15 mL
combined acids (MD2), dilute tovolumewithH
2
O,mix, and
transfer to acid-washed polyethylene bottle. (
6
)
Std1
.—Pipet
0.1 mL stock standard solution into a 100 mL acid-washed
volumetric flask. Add 10 mL analytical grade HNO
3
(SLV,
MD1)or15mLcombinedacids(MD2),dilutetovolumewith
H
2
O, mix, and transfer to acid-washed polyethylene bottle.
(
7
)
Blank
.—Add10mLanalytical gradeHNO
3
(SLV,MD1)
or 15mLcombined acids (MD2) into a 100mLacid-washed
volumetricflask,dilute tovolumewithH
2
O,mix, andtransfer
to acid-washed polyethylene bottle. All calibration solutions
are stable for 1week inglass volumetric flasks.
(
c
)
Ionization buffer/internal standard solution for
automatic addition
.—Weigh 12.67 g cesiumchloride into a
1000 mL acid-washed volumetric flask [
Note
:
Ruggedness
tests
.—Weigh 1.27 g cesium chloride. Cesium 0.1% (w/v)
solution was tested as the minimal recommended
concentration required for element analysis in most food
matrixes.Cs solution1%(w/v) is recommended if anelement
is present at low concentration in high-salted food raw
materials (e.g., culinary products or tastemakers) or if it is
analyzed as an impurity in food-grade salts. Add 40 mL
indium1000mg/Land10mLeachof strontium, yttrium, and
chromium1000mg/L stock solutions, as internal standards.
Add 10 mL analytical grade HNO
3
. Dilute to volume with
H
2
O,mix, and transfer toanacid-washedpolyethylenebottle.
(
Note
: Reagent concentrations assume the use of same pump
tubing internal diameter for both internal standard/ionization
P
OITEVINETAL.
: J
OURNALOF
AOACI
NTERNATIONAL
V
OL
. 92,N
O
. 5, 2009
1487
Table 3. Open-vesselmicrowavedigestionprogram
(CEMMDS2000) used forMD2 ruggedness test
No. of samples
todigest
Power
a
Hold time,min
(step1)
Hold time,min
(step2)
5
23
20
10
6
27
20
10
7
31
20
10
8
35
20
10
9
39
20
10
10
43
20
10
11
47
20
10
12
51
20
10
a
Power expressed in%ofmaximumpower (600watts forCEM
MDS2000system).
Table 4. ICP-AESconditions (VarianVistaAXPRO) for
SLV,MD1, andMD2 ruggedness tests
Instrument
VarianVistaProAX
RFgenerator
40MHz
RFpower
1100W
Torchquartz injector id
2.5mm
Argon flowrate
Plasma18L/min
Auxiliary2.25L/min
Nebulizer 0.8L/min
Spray chamber
Cyclonic thermostated (water
cooled)
Nebulizer
Microconcentric
Pump
Peristaltic, 3channels
Pump tubing id
0.64mm
Sample flowrate
0.75mL/min
Polychromator
Echelle
Resolution
6.9pmatMo202.032nm
Detector
SegmentedCCD
MTE-01
FORWORKINGGROUP/ERPUSEONLY
DONOTDISTRIBUTE
