Search

This paper describes a novel aerosol chemiluminescence-based detector, which can be coupled to liquid chromatography for the determination of the chemicals with weak optical absorbance in the UV-visible region. This aerosol chemiluminescence (CL)-based detector, in which HPLC effluent is converted to aerosol and then generated CL emission on the surface of porous alumina, is composed of three main processes: nebuliztion of HPLC effluent, CL emission on surface of porous alumina material, and optical detection. To demonstrate the utility of the aerosol chemiluminescence detector, some compounds such saccharides, poly(ethylene glycol)s, amino acids, and steroid pharmaceuticals are determined by the present aerosol chemiluminescence detection method. Compared with an evaporative light scattering detector, the proposed detector shows the following features: (a) extensive CL emissions on porous alumina by many compounds tested, which leads to the potential application for the determination of volatile and nonvolatile chemicals with or without UV-visible absorbance; (b) a CL mechanism based on the catalytic oxidation of analytes, not on the light scattering, which suggests the present detector be free from the interference of the inorganic and nonvolatile mobile-phase modifiers. The CL characteristics and effect of different parameters, such as temperature and nebulizer gas flow rate, were also discussed in this paper. Furthermore, this aerosol chemiluminescence-based detector was successfully applied to the determination of raffinose, glucose, sucrose, maltose, and [alpha]-lactose.

Yb3+/Er3+ co-dopants sodium yttrium fluoride micro-powders were synthesized by a combustion method and the luminescence properties investigated. The results indicated that the up-conversion material synthesized by this method has high up-conversion efficiency and the fluorescence spectrum peak was sharp. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Different crystal structure of TeO2 nanoparticles were used as the host materials to prepare the Er3+/Yb3+ ions co-doped upconversion luminescent materials. The TeO2 nanoparticles mainly kept the original morphology and phase after having been co-doped the Er3+/Yb3+ ions. All the as-prepared TeO2:Er3+/Yb3+ nanoparticles showed the green emissions (525nm, 545nm) and red emission (667nm) under 980nm excitation. The green emissions at 525nm, 545nm and red emission at 667nm were attributed to the 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of the Er3+ ions, respectively. For the α-TeO2:Er3+/Yb3+ (3/10mol%) nanoparticles, three-photon process involved in the green (2H11/2 → 4I15/2) emission, while two-photon process involved in the green (4S3/2→4I15/2) and red (4F9/2 → 4I15/2) emissions. For the β-TeO2:Er3+/Yb3+ (3/10mol%) nanoparticles, two-photon process involved in the green (2H11/2 → 4I15/2), green (4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) emissions. It suggested that the crystal structure of TeO2 nanoparticles had an effect on transition processes of the Er3+/Yb3+ ions. The emission intensities of the α-TeO2:Er3+/Yb3+ (3/10mol%) nanoparticles and β-TeO2:Er3+/Yb3+ (3/10mol%) nanoparticles were much stronger than those of the (α+β)-TeO2:Er3+/Yb3+ (3/10mol%) nanoparticles. [Copyright &y& Elsevier]