3.4. Accuracy/recovery and precision
Accuracy/recovery was calculated for nine runs of each solution,
involving both o/w emulsion and aqueous gel. The results,
recorded in Table 1, indicated an adequate percentage of accu-racy/recovery (oil-in-water emulsion−98.97 to 100.84%; aqueous
gel −95.46 to 101.54%) of the HPLC stability-indicating
method for ascorbic acid quantitation from the pharmaceutical/
cosmetic preparations.
To calculate the precision, intra- and inter-days tests were
performed and results were expressed as relative standard deviation
(R.S.D., %) in terms of area ratio of ascorbic acid/nicotinic
acid. The low percentage values of R.S.D. (0.38 and 1.22%)
were an evidence of the appropriate precision of this stabilityindicating
method which provided an irrelevant variability of the
data assayed in 3 (mean of the 10 injections) and 6 days (mean
of 6 injections) [30–32].