Optimization and Validation of an HPLC-Photodiode Array Detector Method for Determination of Organic Acids in Vinegar

A novel isocratic RP–HPLC method with UV photodiode array detection for the determination of seven organic acids in vinegar samples was developed and optimized. Samples were analyzed on a C18 (150 × 4.6 mm id, 5 μm) analytical column. Methanol–0.010 M sodium dihydrogen phosphate buffer adjusted with H3PO4 to pH 2.80 (2 + 98, v/v), was used as the mobile phase. The column oven temperature was optimized at 23.0°C, the flow rate was 0.80 mL/min, and the detection wavelength was 210 nm. Matrix-matched calibration curves were prepared for all analytes, and the correlation coefficients were greater than 0.99. LOD and LOQ ranged from 0.10 to 10.0 and 0.30 to 30.0 μg/mL, respectively. The results for interday and intraday precision and accuracy fell within the ranges specified. Vinegar samples were quantified by the standard addition method. The main advantages of this method are its selectivity, which is one of themain weaknesses of most methods when determining organic acids in complex matrixes, and its simplicity since little sample preparation is needed. Moreover,it is safe and inexpensive with low organic solvent usage.