2.4 Preparation of Stock and StandardSolutions
Stock solutions of benzoic acid and sorbic acid in methanol were prepared at a concentration of 2.5 and 1.25 mg/mL, respectively. A series of standard mixture solutions was prepared by the appropriate dilution of the stock standard solutions with methanol to concentration range of 5-200 μg/ mL for benzoic acid and 1-50 μg/mL for sorbic acid.