Analysis of low molecular weight organic acids in several complex liquid biological systems via HPLC with switching detection wavelength

In this study, we established an effective method to determine the composition of low molecular weight organic acids (LMWOA) in several complex liquid biological systems via high performance liquid chromatography (HPLC) with switching detection wavelengths. A Shim-pack VP-ODS-C18 column was used for the HPLC and the temperature was optimized to 30 °C. A mixture of 0.01 M KH2PO4 and acetonitrile was used as the mobile phase and the column flow rate was 0.6 mL/min. Samples were eluted with a non-linear gradient. Compared with constant detection wavelength, the switching method improved the sensitivity and made all LMWOA analyzed at their maximum absorption wavelength. The linearity of the calibration curves for each organic acid in the desired concentration range was found to be good (r2 > 0.9991). The method is accurate and precise with recoveries ranging from 99.06% to 101.56% and both intra-day and inter-day variabilities (%RSD) <2%. PDA peak purity test confirmed the specificity of the method. The chromatographic parameters, such as flow rate, mobile phase pH and column temperature, were evaluated for robustness and determined to be acceptable. The applicability of the proposed method was demonstrated by analyzing these 11 LMWOA in real samples such as red wine, white wine, table vinegar, fruit juices and root exudates.