Method precision was evaluated at three levels: repeatability,
intermediate precision and reproducibility. The intra-day precision
(repeatability) was evaluated using the results of six preparations
each containing nine fatty acids. The RSD of oleic acid was less
than 3.0% and the RSDs of fatty acids (individual) were found to be
2.0%–6.6% (Table 5). The intermediate precision was evaluated by
data generated on different days. The difference of the mean from
two days ranged from 0.14% to 2.90% (Table 6). The reproducibility
was evaluated by comparing data from two different laboratories
(Lab A and Lab B). The percentage of oleic acid in oleic
acid USP-NF materials (vegetable origin) was measured as 87.39%
by Lab A and 87.57% by Lab B. The RSD of oleic acid measurements
in the two laboratories was found to be 0.14%, indicating the validated
test method is reproducible. Furthermore, the method was
also evaluated by comparing the data obtained using this validated
test method to the vendor's data using the Ph. Eur. method. The
results in Table 7 demonstrated that the data were comparable.