CASTDan:Abstract7

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Kostov Y., Van Houten, K.A., Harms, P., Pilato, R.S., Rao, G. (2000) A unique oxygen analyzer combining dual emission probe and low-cost ratiometric fluorimeter. Applied Spectroscopy 54, 864-868.

Abstract

A new oxygen analyzer combining a polymer-encapsulated dualemission probe and a diode-based ratiometric fluorometer is described. The ratiometric fluorometer was configured to measure the relative fluorescence and phosphorescence intensity of the shortlived singlet and long- lived oxygen-quenchable triplet of [(dppe)Pt{S2C2(CH2CH2-N- 2-pyridinium)}](BPh4), where dppe is 1,2-bis(diphenylphosphino)ethane. This luminescent dye was immobilized at 0.3% by weight in cellulose acetate/75% triethylcitrate and cast into a 0.5 mm-thick film. The dye molecule was excited with a blue light-emitting diode (LED) and the singlet and triplet emissions monitored by individual photodiodes at 570 and 680 nm, respectively. Oxygen can be accurately measured without interference from nonanalyte-induced intensity changes by monitoring the relative output of the two photodiodes. The output of the device was linear with oxygen concentration. The PO2(1/2) from the ratioadapted Stern┬▒ Volmer plot was 9.6% oxygen ( ~73 torr), offering a dynamic range of 0┬▒ 90% O2. The device is stable and the oxygen measurements reproducible. Intentional photobleaching of ~ 20% of the sensor dye had little effect upon the reproducibility of the oxygen measurements.

Index Headings: Oxygen analyzer; Ratiometric sensor; Low-cost fluorimeter.


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