'Rough guide' evanescent wave optrode for colorimetric metalloporphyrine sensors

TALANTA

卷:164

Article

Tuwei, Abraham Kirwa^1,5  Williams, Nicholas H.³  Mulla, Mohammad Yusuf²  Di Natale, Corrado²  Paolesse, Roberto⁴  Grell, Martin¹ 

[1] Univ Sheffield, Dept Phys & Astron, Sheffield S3 7RH, S Yorkshire, England

[2] Univ Roma Tor Vergata, Dept Elect Engn, Via Politecn 1, I-00133 Rome, Italy

[3] Univ Sheffield, Dept Chem, Ctr Chem Biol, Sheffield S3 7HF, S Yorkshire, England

[4] Univ Roma Tor Vergata, Dept Chem Sci & Technol, Via Ric Sci, I-00133 Rome, Italy

[5] Chuka Univ, Dept Phys Sci, POB 109, Chuka, Kenya

关键词: Optrode;    Evanescent wave;    Amine;    Metalloporphyrin;    Lock-in;   

DOI  :  10.1016/j.talanta.2016.11.057

来源: Elsevier

【 摘 要 】

When films of zinc 5-(4-carboxyphenyl),10,15,20-triphenyl porphyrin (ZnTPP) are exposed to waterborne amine in pH- neutral or alkaline media, both Q- band and Soret band respond with a change of absorbance due to the donation of amine 'lone pair' electrons to the metalloprophyrin pi orbital. However, this is difficult to reveal with a conventional spectrometer even under high amine concentration. We therefore introduce optical fibres coated with ZnTPP into a bespoke 'light balance' evanescent wave absorbance meter [doi:10.1016/ j.snb.2016.05.065]. The light balance makes absorbance changes clearly visible under only 5 M aqueous amine, making PVC membranes redundant. We find sensitivity is higher, and limit- of- detection lower, in the Soret band rather than the Q- band, reflecting the stronger Soret band absorbance. Also, we find that sensitivity is higher, and limit- of- detection approximately two times lower, when rough rather than smooth fibres are used. We believe the rough fibre surface leads to enhanced evanescence, and therefore better overlap of the wave propagating in the fibre with the ZnTPP fibre cladding. We find a limit of detection to waterborne amines below 1 M, which compares well to other sensors for waterborne amines [Korent, S.M. et.al. Anal. Bioanal. Chem. 387 (2007) 2863-2870; Algarni, S. A. et.al. Talanta 153 (2016) 107-110]. We therefore recommend 'rough guide' evanescent wave optrodes, in combination with sensitive 'light balance' detector, to succeed membrane embedding of colorimetric sensitisers such as metalloporphyrines.

【 授权许可】

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