HPLC determination of oxalic acid using tris(1,10-phenanthroline)ruthenium(II) chemiluminescence—application to the analysis of spinach

The chemiluminescence (CL) of Ru(phen)32+ was applied to HPLC determination of oxalic acid. Oxalic acid was separated by a C18 reverse-phase column with a mobile phase of 0.02 mol/l NH4Ac. The eluted oxalic acid was mixed with 0.25 mol/l Ru(phen)32+ and 2.0 mmol/l Ce(SO4)2 in 0.08 mol/l H2SO4, and then pass through a modified luminometer used as a detector. The reaction of Ce(IV) oxidized Ru(phen)32+ and oxalic acid emitted light. The detection limit was 6.2×10−6 mol/l for oxalic acid at a S/N ratio of 3, the relative standard deviation for 5 replicate injections of 1×10−3 mol/l oxalic acid standard was calculated as 5.6%, and the linear calibration range was 1×10−5 to 4×10−3 mol/l. The method was successfully applied to determination of oxalic acid in spinach. ©