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Determination of phosphate using a highly sensitive paired emitter-detector diode photometric flow detector
O'Toole, Martina; Lau, King-Tong; Shepherd, Roderick; Slater, Conor; Diamond, Dermot
The use of a novel inexpensive photometric device, Paired Emitter Detector Diode (PEDD) has been applied to the colorimetric determination of phosphate using the malachite green spectrophotometric method. The novel miniaturized flow detector applied within this manifold is a highly sensitive, low cost, miniaturized light emitting diode (LED) based detector. The optical flow cell was constructed from two LEDs, whereby one is the light source and the second is the light detector, with the LED light source forward biased and the LED detector reversed biased. The photocurrent generated by the LED light source discharges the junction capacitance of the detector diode from 5 V (logic 1) to 1.7 V (logic 0) and the time taken for this process to occur is measured using a simple timer circuit. The malachite green (MG) method employed for phosphate determination is based on the formation of a green molybdophosphoric acid complex, the intensity of which is directly related to phosphate concentration. Optimum analytical parameters such as reaction kinetics, reagent to sample concentration ratio and emitter wavelength intensity were investigated for the spectrophotometric method. Linear calibration plots that obeyed the Beer-Lambert Law were obtained for phosphate in the range of 0.02-2 ┬ÁM. The dynamic range, sensitivity and limits of detection are reported.
Keyword(s): Analytical chemistry; Environmental chemistry; Detectors; Chemistry; Light emitting diode detector; Malachite green; Phosphate; Colorimetric flow analysis
Publication Date:
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 <>, Shepherd, Roderick, Slater, Conor and Diamond, Dermot ORCID: 0000-0003-2944-4839 <> (2007) Determination of phosphate using a highly sensitive paired emitter-detector diode photometric flow detector. Analytica Chimica Acta, 597 (2). pp. 290-294. ISSN 0003-2670
Publisher(s): Elsevier
File Format(s): application/pdf
Related Link(s):,
First Indexed: 2009-11-05 02:01:23 Last Updated: 2019-02-09 06:59:50