Post-column detection of benzenediols and 1,2,4-benzenetriol based on acidic potassium permanganate chemiluminescence

Based on the sensitizing effect of formic acid on the chemiluminescence (CL) reaction of polyhydroxylbenzenes with acidified potassium permanganate and the combination technique of high-performance liquid chromatography (HPLC), a sensitive, selective and simple post-column CL detection method for simultaneously determining catechol, resorcinol, hydroquinone and 1,2,4-benzenetriol is described. The optimal conditions for the CL detection and HPLC separation were carried out. The linear ranges were: 6.0 × 10⁻³-1.5 mg/L for hydroquinone, 8.0 × 10⁻³-1.5 mg/L for 1,2,4-benzenetriol, 1.0 × 10⁻²-2.0 mg/L for resorcinol and 1.0 × 10⁻²-2.5 mg/L for catechol, respectively. The detection limits are: 3.2 × 10⁻³ mg/L for hydroquinone, 3.9 × 10⁻³ mg/L for 1,2,4-benzenetriol, 4.7 × 10⁻³ mg/L for resorcinol and 5.2 × 10⁻³ mg/L for catechol, respectively. Combining with solid phase extraction, the proposed method has been successfully applied to the determination of the polyhydroxylbenzenes in river water. The recoveries for three benzentriols were 92.1-95.4% and 82.0% for 1,2,4-benzenetriol, respectively.