Ultrasound-enhanced flow injection chemiluminescence for determination of hydrogen peroxide

Abstract

A novel ultrasonic flow injection chemiluminescence (FI-CL) manifold for determining hydrogen peroxide (H₂O₂) has been designed and evaluated. Chemiluminescence obtained from the luminol–H₂O₂–cobalt(II) reaction was enhanced by applying 120 W of ultrasound for a period of 4 s to the reaction coil in the FI-CL system and this enhancement was verified by comparison with an identical manifold without ultrasound. The system was developed for determining ultra-trace levels of H₂O₂ and a calibration curve was obtained with a linear portion over the range of 10–200 nmol L⁻¹ H₂O₂ (correlation coefficient 0.9945). The detection limit (3σ) and the quantification limit (LOQ) were found to be 1 × 10⁻⁹ and 3.3 × 10⁻⁹ mol L⁻¹ respectively and the relative standard deviation was 1.37% for 2 × 10⁻⁷ mol L⁻¹ H₂O₂ (n = 10). The method was applied to the determination of trace amounts of H₂O₂ in purified water and natural water samples without any special pre-treatments.