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Photometric detection in flow analysis systems using integrated PEDDs
O'Toole, Martina; Lau, King-Tong; Diamond, Dermot
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.
Keyword(s): Detectors; Chemistry; LEDs; Optical sensing; pH sensing; Transmission measurements; Colorimetric analysis
Publication Date:
2005
Type: Other
Peer-Reviewed: Unknown
Language(s): English
Institution: Dublin City University
Citation(s): O'Toole, Martina, Lau, King-Tong ORCID: 0000-0001-7818-7010 <https://orcid.org/0000-0001-7818-7010> and Diamond, Dermot ORCID: 0000-0003-2944-4839 <https://orcid.org/0000-0003-2944-4839> (2005) Photometric detection in flow analysis systems using integrated PEDDs. Talanta, 66 (5). pp. 1340-1344. ISSN 0039-9140
Publisher(s): Elsevier
File Format(s): application/pdf
Related Link(s): http://doras.dcu.ie/2975/1/Martina_O%27_Toole_20_jan_05.pdf,
http://dx.doi.org/10.1016/j.talanta.2005.01.054
First Indexed: 2009-11-05 02:01:23 Last Updated: 2019-02-09 06:59:51