Determination of organic acids in plants of Silene paradoxa L. by HPLC

According to the general behavior that organic acids steadily bind metals, a specific and highly reproducible HPLC separation method with photodiode array detection has been improved for their determination and quantification in biological materials. The separation was carried out on an Alltima C-18 reverse phase column. The mobile phase was 125 mM KH2PO4, adjusted to pH 2.5 with concentrated H3PO4, and optimum separation efficiency was obtained by using a 2 mL min(-1) flow rate. Detection wavelength for quantitative measurement was 210 nm. The run time of each sample was 20 min, with a spectra collection frequency of 5 spectra s(-1). Organic acids were identified by comparing the retention times of the samples against retention times of the standards and confirmed with spectral (190 - 700 nm) signature. Because organic acids could steadily bind metals in plant tissues and due to the strong matrix effect observed, the addition method was applied for quantitative analysis and its performance evaluated.