Analytical Sciences

Automatic Multi-pumping Flow System for the Chemiluminometric Screening of Scavenging Capacity against Singlet Oxygen

Ana F. T. SILVA, Karine L. MARQUES, João L. M. SANTOS, and José L. F. C. LIMA

REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4099-030, Porto, Portugal

An automated multi-pumping flow system was developed for the in-line generation of singlet oxygen (¹O₂) and subsequent assessment of the scavenging capacity against this reactive species. ¹O₂ was generated by dismutation of hydrogen peroxide catalyzed by molybdate ions. The evaluation of the scavenging capacity was based on the inhibition of the chemiluminescence reaction of luminol with ¹O₂. The proposed system used solenoid micro-pumps as the only active components of the flow manifold, enabling the reproducible insertion and efficient mixing of sample and reagents as well as the transportation of the sample zone towards detection for chemiluminescence measurement, assuring a strictly reproducible timing of all analytical tasks. Several compounds were evaluated as possible ¹O₂ scavengers. The obtained results showed that only ascorbic acid, dipyrone and tryptophan exhibited scavenging capacity, with IC₅₀ values of 3.36 × 10⁻⁵, 7.84 × 10⁻⁵ and 1.28 × 10⁻² mol L⁻¹, respectively.

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