Chemistry Reference
In-Depth Information
tAble 4.2
determination of repeatability by replicate Injections
Injection
response
1
626225
2
625890
3
625110
4
625447
5
625666
6
624398
Mean
625456
Standard deviation
642.34
RSD
0.10%
Acceptance criteria (RSD)
≤2%
Assessment
Pass
tAble 4.3
measurement of Intermediate precision
Amount
Analyst one
Analyst two
Mean
25.9 mg
26.0 mg
Std. Dev.
0.07 mg
0.05 mg
%RSD
0.27
0.19
%Difference (means)
0.39
Acceptance criteria (RSD)
≤2%
Assessment
Pass
and solutions, used a column from a different lot, and used a different HPLC system
to evaluate the sample solutions. Each analyst successfully attained the precision
requirements of ≤2% RSD, and the %Difference in the mean values between the two
analysts was 0.39%, which indicates that there is no difference in the mean values
obtained (Student's
t
-test,
P
= 0.01).
4.3.2.3 reproducibility
Reproducibility refers to the results of collaborative studies among different laborato-
ries. Documentation in support of reproducibility studies should include the standard
deviation, relative standard deviation (or coefficient of variation), and the confidence
interval. Table 4.4 lists some results typical of a reproducibility study. To generate the
data shown here, analysts from two different laboratories (different from the analysts
involved in the intermediate precision) prepared and analyzed six sample prepara-
tions from one product batch and two preparations each from two additional batches
(all samples were assumed to be the same concentration). Each analyst prepared his
or her own standards and solutions, used a column from a different lot, and used a
