3.4. Method validation
Five concentrations of glucosamine standards were analyzed
and the results plotted as peak area counts against glucosamine
concentration (Fig. 5). The correlation between the two parameters
is linear with a correlation coefficient R2 > 0.999.
The assay repeatability and intermediate precision were calculated
by determining the relative standard deviation of the results,
as recorded in Table 1. The relative standard deviations (RSD) of five
replicate analyses (repeatability) for the chitosan and formulations
are 0.93% and 1.67%, respectively, for analyst 1, and 5.25% and 5.49%,
respectively, for analyst 2. The overall RSD (reproducibility) were
4.52% for the analysis of chitosan and 3.84% for the analysis of the
formulation. The assay reproducibility for measuring glucosamine
content was within 5% of the nominal content for both chitosan and
the formulations.
The recovery of chitosan from the matrix samples was calculated
as percentage of the glucosamine spike. Chitosan recovery for
the three formulations (50, 100, and 150% of target chitosan) was
between 99 and 103%, demonstrating the accuracy of the method.