P
OITEVINETAL.
: J
OURNALOF
AOACI
NTERNATIONAL
V
OL
. 92,N
O
. 5, 2009
1507
Table 23. MD1–4 ruggedness tests: accuracy, precision, andHorRat values found for potassiumin fivecertifiedand in-house referencematerialsusing
recommended lines
Material description
-test code
a
Referencevalue,
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
Chocolatemilkpowder
MD1
9090±133
9145
101±2
0.73
115
237
1.3
2.6
0.5
MD2
8915
98±2
0.34
71
317
0.8
3.6
0.6
MD3
9025
99±2
0.65
65
130
0.7
1.4
0.2
MD4
9031
99±2
0.69
39
153
0.4
1.7
0.3
Infant cereals
MD1
6500±50
6830
105±2
0.006
200
250
2.9
3.7
0.6
MD2
6450
99±1
0.56
80
180
1.2
2.8
0.5
MD3
6360
98±1
0.06
50
120
0.8
1.9
0.3
MD4
6260
96±1
0.03
100
210
1.6
3.3
0.5
Cornbran
MD1
566±38
460
81±7
0.02
15
59
3.3
12.6
1.4
MD2
463
82±6
0.02
10
41
2.1
8.8
1.0
MD3
538
95±7
0.48
7
35
1.4
6.3
0.7
MD4
561
99±8
0.91
13
73
2.4
13.1
1.5
Dieteticmilkpowder 1
MD1
5570±25
5678
102±1
0.007
43
52
0.8
0.9
0.1
MD2
5633
101±1
0.32
65
158
1.1
2.8
0.5
MD3
5561
100±1
0.83
30
99
0.5
1.8
0.3
MD4
5640
101±1
0.08
32
75
0.6
1.3
0.2
Nonfatmilkpowder
MD1
16900±150
16610
98±1
0.10
180
200
1.1
1.2
0.5
MD2
16230
96±1
0.01
220
450
1.4
2.8
0.3
MD3
16580
98±1
0.10
80
250
0.5
1.5
0.3
MD4
16730
99±1
0.30
220
230
1.3
1.4
0.9
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
