TY - JOUR
T1 - Determination of phosphate using a highly sensitive paired emitter-detector diode photometric flow detector
AU - O'Toole, Martina
AU - Lau, King Tong
AU - Shepherd, Roderick
AU - Slater, Conor
AU - Diamond, Dermot
N1 - Funding Information:
The authors wish to thank Science Foundation Ireland SFI for grant support under the Adaptive Information Cluster Award (SFI 03/IN3/1361), and to acknowledge the assistance of Mitsubishi Electric Research Laboratory, Cambridge, MA, in the development of the PEDD detector concept.
PY - 2007/8/10
Y1 - 2007/8/10
N2 - The use of a novel inexpensive photometric device, a 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 μM. The dynamic range, sensitivity and limits of detection are reported.
AB - The use of a novel inexpensive photometric device, a 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 μM. The dynamic range, sensitivity and limits of detection are reported.
KW - Colorimetric flow analysis
KW - Light emitting diode detector
KW - Malachite green
KW - Phosphate
UR - http://www.scopus.com/inward/record.url?scp=34547517498&partnerID=8YFLogxK
U2 - 10.1016/j.aca.2007.06.048
DO - 10.1016/j.aca.2007.06.048
M3 - Article
C2 - 17683741
AN - SCOPUS:34547517498
SN - 0003-2670
VL - 597
SP - 290
EP - 294
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
IS - 2
ER -