Photoactivation by visible light of CdTe quantum dots for inline generation of reactive oxygen species in an automated multipumping flow system

• Published in: Analytica chimica acta 2012-07, Vol.735, p.69-75
• Main Authors: Ribeiro, David S.M., Frigerio, Christian, Santos, João L.M., Prior, João A.V.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Antioxidants - analysis; Automated; Bronchodilator Agents - analysis; Cadmium Compounds - chemistry; Cadmium tellurides; Chemical and thermal methods; Chemiluminescence; Chemistry; Epinephrine; Epinephrine - analysis; Equipment Design; Exact sciences and technology; Formulations; Light; Light-emitting diodes; Limit of Detection; Luminescent Agents - chemistry; Luminescent Measurements - instrumentation; Luminescent Measurements - methods; Luminol - chemistry; Multipumping flow system; Oxidation-Reduction; Pharmaceutical Preparations - chemistry; Pharmaceuticals; Photochemical Processes; Quantum Dots; Reactive oxygen species; Reactive Oxygen Species - chemistry; Semiconductors; Tellurium - chemistry; Visible light photoirradiation
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2012.05.034

[Display omitted] ► CdTe quantum dots generate free radical species upon exposure to visible radiation. ► A high power visible LED lamp was used as photoirradiation element. ► The laboratory-made LED photocatalytic unit was implemented inline in a MPFS. ► Free radical species oxidize luminol producing a strong chemiluminescence emission. ► Epinephrine scavenges free radical species quenching chemiluminescence emission. Quantum dots (QD) are semiconductor nanocrystals able to generate free radical species upon exposure to an electromagnetic radiation, usually in the ultraviolet wavelength range. In this work, CdTe QD were used as highly reactive oxygen species (ROS) generators for the control of pharmaceutical formulations containing epinephrine. The developed approach was based on the chemiluminometric monitoring of the quenching effect of epinephrine on the oxidation of luminol by the produced ROS. Due to the relatively low energy band-gap of this chalcogenide a high power visible light emitting diode (LED) lamp was used as photoirradiation element and assembled in a laboratory-made photocatalytic unit. Owing to the very short lifetime of ROS and to ensure both reproducible generation and time-controlled reaction implementation and development, all reactional processes were implemented inline by using an automated multipumping micro-flow system. A linear working range for epinephrine concentration of up to 2.28×10−6molL−1 (r=0.9953; n=5) was verified. The determination rate was about 79 determinations per hour and the detection limit was about 8.69×10−8molL−1. The results obtained in the analysis of epinephrine pharmaceutical formulations by using the proposed methodology were in good agreement with those furnished by the reference procedure, with relative deviations lower than 4.80%.