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)(3)(2+) was applied to HPLC determina tion of oxalic acid. Oxalic acid was separated by a C-18 reverse-phase colu mn with a mobile phase of 0.02 mol/l NH4Ac. The eluted oxalic acid was mixe d with 0.25 mol/l Ru(phen)(3)(2+) and 2.0 mmol/l Ce(SO4)(2) in 0.08 mol/l H 2SO4, and then pass through a modified luminometer used as a detector. The reaction of Ce(IV) oxidized Ru(phen)(3)(2+) and oxalic acid emitted light. The detection limit was 6.2 x 10(-6) mol/l for oxalic acid at a S/N ratio o f 3, the relative standard deviation for 5 replicate injections of 1 x 10(- 3) mol/l oxalic acid standard was calculated as 5.6%, and the linear calibr ation range was 1 x 10(-5) to 4 x 10(-3) mol/l. The method was successfully applied to determination of oxalic acid in spinach. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.