Validation of a HPLC Method for the Determination of Benzoic Acid and Sorbic Acid in Noodles

A simple, sensitive and specific HPLC method was validated for the simultaneous determination of benzoic acid and sorbic acid in noodles. Sample preparation involved the extraction with methanol and water (60:40, v/v). The separation was achieved on a GerminiC18 modified silica column (50 mm x 4.6 mm i.d., 5 μm particle diameter). The mobile phase consisted of 0.05 M ammonium acetate (pH 4.4) and methanol in the ratio of 60:40 (% v/v) at a flow rate of 1 mL/min and detection was performed at 234 nm using a diode-array detector (DAD). The method was validated with respect to specificity, linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and robustness. The calibration curve for benzoic acid and sorbic acid was found to be linear in the concentration range of 5-200 μg/mL (r2 0.9998) and 1-50 μg/mL (r2 0.9998), respectively. The values of LOD and LOQ were 0.42 and 1.14 μg/mL and 0.32 and 0.99 μg/mL for benzoic acid and sorbic acid, respectively. The accuracy determined by spike recovery measurement was 85.61-102.04% for benzoic acid and 83.62-102.47% for sorbic acid. The method and intermediate precision for benzoic acid and sorbic acid were demonstrated by the relative standard deviation of 1.84% and 2.40% and 1.41% and 2.80%, respectively. The validation acceptance criteria were met in all cases. The proposed method was successively applied for monitoring of benzoic acid and sorbic acid in 5 different kinds of noodles.