Linearity was established by least squares
linear regression analysis of the calibration
curve and evaluated by a determination
coefficient (r2
) using data analysis MS excel
software (2007) (ANOVA; P < 0.05). Standard
mixture solutions of benzoic acid and sorbic
acid at seven different concentrations (ranging
from 5 to 200 μg/mL and 1 to 50 μg/mL,
respectively) were prepared and analyzed in
triplicate to prove the linearity of system.
Peak area of benzoic acid and sorbic acid
solution was plotted against their respective
concentrations. The calibration curve of
benzoic acid and sorbic acid showed good
linearity over the concentration range with r2
0.9998 and 0.9998, respectively. The statistical
data of the regression equation is presented
in Table 2.