1512
P
OITEVINETAL.
: J
OURNALOF
AOACI
NTERNATIONAL
V
OL
. 92,N
O
. 5, 2009
Table 28. MD1–4 ruggedness tests: accuracy, precision, andHorRat values found for zinc in threecertifiedand in-house referencematerialsusing recommended
lines (MD1,MD2,MD3) andalternate2ZnI line (MD4 )
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
18.6±1.1
17.6
95±6
0.38
0.2
0.5
1.1
2.8
0.2
MD2
17.0
92±5
0.17
0.2
0.3
1.4
1.7
0.1
MD3
17.5
94±6
0.38
0.5
1.4
3.1
8.3
0.6
MD4
18.3
98±7
0.83
0.8
2.4
4.5
13.6
0.9
Dieteticmilkpowder 1
MD1
74.8±0.6
72.5
97±1
0.006
1.1
0.9
1.5
1.3
0.1
MD2
72.6
97±1
0.03
0.6
1.8
0.9
2.4
0.2
MD3
75.3
101±3
0.78
1.0
5.0
1.3
6.7
0.6
MD4
76.3
102±1
0.12
1.2
1.9
1.6
2.5
0.2
Nonfatmilkpowder
MD1
46.1±1.1
45.6
99±2
0.69
0.7
0.9
1.5
2.0
0.2
MD2
44.8
97±2
0.28
0.7
0.9
1.6
2.0
0.2
MD3
45.1
98±2
0.38
0.7
0.9
1.6
2.0
0.2
MD4
46.4
101±3
0.83
0.9
2.1
1.9
4.7
0.4
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
