P
OITEVINETAL.
: J
OURNALOF
AOACI
NTERNATIONAL
V
OL
. 92,N
O
. 5, 2009
1505
Table 21. MD1–4 ruggedness tests: accuracy, precision, andHorRat values found for copper in threecertifiedand in-house referencematerialsusing
recommended lines
Material description
-test code
a
Reference
value,mg/kg
b,c
Median,
mg/kg
Recovery,%
P
-value
d
SD
r
,mg/kg
e
SD
iR
,mg/kg
f
RSD
r
,% RSD
iR
,% HorRat
g
Cornbran
MD1
2.47±0.20
2.39
97±9
0.74
0.06
0.32
2.7
13.1
0.7
MD2
2.39
97±11
0.78
0.06
0.55
2.5
22.9
1.2
MD3
2.27
92±8
0.32
0.07
0.17
3.0
7.5
0.4
MD4
2.47
100±10
0.99
0.11
0.12
4.3
4.7
0.2
Dieteticmilkpowder 1
MD1
7.55±0.13
7.73
102±2
0.29
0.33
0.40
4.3
5.3
0.3
MD2
7.59
101±2
0.83
0.06
0.35
0.8
4.6
0.3
MD3
7.61
101±2
0.76
0.10
0.35
1.3
4.6
0.3
MD4
7.79
103±2
0.20
0.30
0.38
3.9
5.0
0.3
Nonfatmilkpowder
MD1
0.70±0.05
0.52
74±20
0.23
0.08
0.41
13.1
67.6
2.7
MD2
0.59
84±21
0.46
0.04
0.39
6.0
67.0
2.8
MD3
0.47
67±8
0.004
0.06
0.13
12.8
29.6
1.2
MD4
0.74
105±27
0.85
0.13
0.52
18.9
73.6
3.1
a
Ruggedness test usingdifferentmicrowavedigestionsystemsand ICP-AESequipment (Table1).
b
SDexpressedashalf of stateduncertainty (NISTandLGCcertifiedmaterials) givenas95%confidence interval.
c
SDexpressedasa reproducibilitySD(in-house referencematerials) calculatedaccording to robust statistics (29).
d
Statisticevaluationof robust
t
-test: Satisfactory result (
P
>0.05); questionable result (0.01<
P
<0.05); unsatisfactory result (
P
<0.01).
e
SD
r
=SDof repeatability.
f
SD
iR
=SDof intermediate reproducibility.
g
HorRat =RatiousingRSD
iR
andHorwitzdenominator according to ref. 32.
MTE-01
FORWORKINGGROUP/ERPUSEONLY
DONOTDISTRIBUTE
