311 / 620
P
oitevin
:
J
ournal of
AOAC I
nternational
V
ol
.
95, N
o
. 1, 2012
181
matched standard calibrant solutions. An ionization buffer
(cesium) and internal standards (chromium, indium, strontium,
and yttrium) are used with or without appropriate in-line
addition to minimize easily ionizable element (EIE) effects and
to correct for physical and chemical interferences.
F. Instrumentation
Note
: ICP-OES equipment must be used by qualified
laboratory personnel who are familiar with the operation and
maintenance of analytical systems; personnel must follow
manufacturer’s directions for safety risk, safety environment,
and use of instruments.
(
a
)
ICP-OES spectrometer
.
____
Instrument with
axial, radial,
or dual view grating configurations and autosampler, capable of
determining multiple wavelengths for each element of interest
with the required sensitivity. A three-channel peristaltic pump
with or without appropriate in-line addition system (e.g., T
connector) are linked between the peristaltic pump and nebulizer
to avoid having to manually add ionization buffer and internal
standards to each sample solution. A thermostatted cyclonic
spray chamber is equipped with a micro-concentric nebulizer or
other components designed to optimize aerosol and maximize
Table 2011.14E. Interlaboratory study results for magnesium
Matrix
Mean, mg/kg Rec., % S
r
, mg/kg
a
RSD
r
, %
b
S
R
, mg/kg
c
RSD
R
, %
d
HorRat No. of labs
e
Outlier labs
f
Chocolate milk powder
1746.74
98 38.46 2.20 51.03
2.92
0.56
8
2–SG
Dietetic milk powder 2
439.31
99
5.57 1.27 13.37
3.04
0.48
9
NS
g
Infant cereal
859.48
98 33.62 3.91 35.38
4.12
0.71
7
2,6–DG
Peanut butter
NIST SRM 2387
1714.02 (1680)
h
102 56.83 3.32 73.68
4.30
0.82
8
2–SG
Wheat gluten
NIST RM 8418
482.05 (510)
h
95
8.52
1.77
16.53
3.43
0.54
9
NS
a
S
r
= SD for repeatability (within laboratory).
b
RSD
r
= RSD for repeatability.
c
S
R
= SD for reproducibility (among laboratories).
d
RSD
R
= RSD for reproducibility.
e
Reporting laboratories minus outliers.
f
SG = Single Grubbs outlier; DG = Double Grubbs outlier.
g
NS = Not significant.
h
Certified or reference values.
Table 2011.14F. Interlaboratory study results for manganese
Matrix
Mean, mg/kg Rec., % S
r
, mg/kg
a
RSD
r
, %
b
S
R
, mg/kg
c
RSD
R
, %
d
HorRat No. of labs
e
Outlier labs
f
Chocolate milk powder
7.54
NA
g
0.14 1.88
0.67
8.82
0.75
9
NS
h
Dietetic milk powder 2
0.40
99
0.01 2.56 0.0197
4.89
0.27
8
2 – C
Infant cereal
16.74
NA 1.14 6.79
1.44
8.61
0.82
9
NS
Peanut butter
NIST SRM 2387
15.85 (16.0)
i
99
0.45 2.86
1.32
8.31
0.79
9
NS
Wheat gluten
NIST RM 8418
12.87 (14.3)
i
90
0.23
1.75
1.13
8.75
0.80
9
NS
a
S
r
= SD for repeatability (within laboratory).
b
RSD
r
= RSD for repeatability.
c
S
R
= SD for reproducibility (among laboratories).
d
RSD
R
= RSD for reproducibility.
e
Reporting laboratories minus outliers.
f
C = Cochran outlier.
g
NA = Not available.
h
NS = Not significant.
i
Certified or reference values.
2011.14 (MTE-01) MLT
FOR ERP USE ONLY
DO NOT DISTRIBUTE