High-performance liquid chromatographic determination of oxalic acid in tea using tris(1,10-phenanthroline)-ruthenium(II) chemiluminescence

The chemiluminescence (CL) of Ru(phen)(3)(2+) was applied to HPLC determination of oxalic acid, which was separated by a C-18 reverse-phase column with a mobile phase of 0.02 mol/l NH4Ac, mixed with 0.25 mol/l Ru(phen)(3)(2+) and 2.0 mmol/l Ce(SO4)(2) (0.08 mol/l H2SO4), and then passed through a homemade CL detector. The reaction of Ce(IV)oxidized Ru(phen)(3)(2+) and the oxalic acid emitted light. The detection limit was 6.2x10(-6) mol/l for oxalic acid at a S/N ratio of 3, the relative standard deviation for 5 replicate injections of 1x10(-3) mol/l oxalic acid standard was calculated as 5.6%, and the linear calibration range was 1x10(-5) to 4x10(-3) mol/l. The method was successfully applied to determination of oxalic acid in tea.