For precision assays, samples in four different concentrations
were analyzed five times and the intra-assay relative standard
deviation (R.S.D.) calculated. Inter-assay R.S.D. was determined
analyzing the samples in seven different days. The intraand
inter-assay accuracy was also evaluated for each concentration,
by assessing the agreement between the measured and
nominal concentrations of the analytes. In addition, the efficiency
of the extraction method (n = 5) was estimated from
formulations containing different concentrations of Vitamins A
and E.