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Photometric detection in flow analysis systems using integrated PEDDs

O'Toole, Martina and Lau, King-Tong and Diamond, Dermot (2005) Photometric detection in flow analysis systems using integrated PEDDs. Talanta, 66 (5). pp. 1340-1344. ISSN 0039-9140

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Abstract

A novel inexpensive optical-sensing technique has been developed for colorimetric flow analysis. This sensing system employs two LEDs whereby one is used as the light source and the other as a light detector. The LED used as light detector is reverse biased with a 5-V supply so that the photocurrent generated by the incident light discharges the capacitance. Direct digital output is provided by a simple timer circuit that measures the time taken for this discharge process from 5 V (logic 1) to 1.7 V (logic 0). This sensing concept has been applied in flow analysis by constructing an optical flow cell with a pair of LEDs. Calibration of the integrated optical flow cell using a dye resulted in a linear response that obeys the Beer–Lambert law. The flow rate, dynamic range, sensitivity and limits of detection were investigated. The system was also used for pH determination in the range of pH 2.5–6.8 using bromocresol green (BCG). The pKa of BCG was successfully determined by this technique.

Item Type:Article (Published)
Refereed:Yes
Uncontrolled Keywords:LEDs; Optical sensing; pH sensing; Transmission measurements; Colorimetric analysis;
Subjects:Physical Sciences > Detectors
Physical Sciences > Chemistry
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Research Initiatives and Centres > Adaptive Information Cluster (AIC)
Research Initiatives and Centres > National Centre for Sensor Research (NCSR)
Publisher:Elsevier
Official URL:http://dx.doi.org/10.1016/j.talanta.2005.01.054
Copyright Information:Copyright © 2005 Elsevier B.V.
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
Funders:Science Foundation Ireland
ID Code:2975
Deposited On:16 Mar 2009 16:19 by martina o'toole. Last Modified 31 Mar 2009 11:40

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