Expressed as the repeatability standard deviation (SD
r
); or % repeatability
51
relative standard deviation (%RSD
r
).
52
53
Reproducibility
54
The standard deviation or relative standard deviation calculated from among-
55
laboratory data. Expressed as the reproducibility relative standard deviation
56
(SD
R
); or % reproducibility relative standard deviation (% RSD
R
).
57
58
Target Measurement Uncertainty (TMU)
59
The maximum measurement uncertainty that will satisfy the intended use of a given
60
method.
4
61
62
4.
Method Performance Requirements:
63
64
Analytical range
5 - 500*
Limit of Quantitation (LOQ)
≤
5
*
Accuracy
95-105%
Repeatability (RSD
r
)
≤
2%
Reproducibility (RSD
R
)
≤
4%
Concentrations apply to: a) ‘ready
-to-
feed” liquids “as is”; b) re
-
constituted powders (25 g into 200 g of water); and c) liquid
concentrates diluted 1:1 by weight using water.
* mg /100 g reconstituted final product.
65
66
5.
System suitability tests and/or analytical quality control:
67
Suitable methods will include blank check samples, and check standards at the
68
lowest point and midrange point of the analytical range.
69
70
6.
Reference Material(s):
NIST Standard Reference Material
®
1849a; Infant/Adult
71
Nutritional Formula - or equivalent. SRM 1849a is a milk-based, hybrid infant/adult
72
nutritional powder. One unit of SRM 1849a contains 10 packets each containing
73
approximately 10 g of material. The reference value of NIST SRM 1849a for chlorine is:
74
7010 mg/kg.
75
76
77
7.
Validation Guidance
:
78
Recommended level of validation:
Official Methods of Analysis
SM
.
79
80
8.
Maximum Time-To-Result
: No maximum time.
81
4
See VIM definition 2.34 for formal definition. Calculated as: TMU =
√
RSD
R
2
+ RSD
r
2
+ U
s
2,
where RSD
R
=
the relative standard deviation of reproducibility; RSD
r
= the relative standard deviation of repeatability; and
U
s
= the uncertainty of the sample.
