Validation, measurement uncertainty, and application of HPLC and LC-MS/MS analysis methods for determining organic acids in processed food products

Organic acids are water-soluble organic compounds that exhibit acidity and are primarily used in the form of food additives to regulate acidity in food products. Among them, tartaric acid, for instance, has shown toxicity in its DL-form, and an acceptable daily intake (ADI) of 240 mg/kg·bw/day has been established for this form. L-(+)-tartaric acid can be converted to the DL-form in food. This study aims to develop and apply a high-performance liquid chromatography (HPLC-DAD) method using a C18 column to quantitatively analyze tartaric acid, malic acid, lactic acid, acetic acid, citric acid, succinic acid, and fumaric acid as food additives. The mobile phase consisted of water with 0.1 % phosphoric acid and methanol, with a flow rate of 1.0 mL/min and a column temperature of 40°C. The calibration curve (0.05–200 mg/L) demonstrated excellent linearity (r² > 0.999). The limit of detection ranged from 0.06 to 1.53 mg/kg, and the limit of quantification ranged from 0.19 to 4.63 mg/kg. The method achieved high accuracy (85.1–100.8 %) and precision (0.62–4.87 %RSD), with measurement uncertainty estimated. Additionally, LC-MS/MS was used for qualitative analysis and cross verification. This technique effectively assesses organic acids across various food concentrations, enabling efficient monitoring and addressing potential health risks associated with these compounds.