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A Novel Type of Tri-Colour Light-Emitting-Diode-Based Spectrometric Detector for Low-Budget Flow-Injection Analysis

View Article: PubMed Central

ABSTRACT

In this paper we describe a low-cost spectrometric detector that can be easily assembled in a laboratory for less than €80 with a minimal number of optical components and which has proved sensitive and flexible enough for real-life applications. The starting point for the idea to construct this small, compact low-cost spectrometric detector was the decision to use a tri-colour light-emitting diode (LED) of the red-green-blue (RGB) type as a light source with the objective of achieving some flexibility in the selection of the wavelength (430 nm, 565 nm, 625 nm) but avoiding the use of optical fibres. Due to the dislocation of the emitters of the different coloured light, the tri-colour LED-based detector required an optical geometry that differs from those that are described in literature. The proposed novel geometry, with a coil-type glass flow-through cell with up to four ascending turns, proved useful and fit for the purpose. The simplicity of the device means it requires a minimal number of optical components, i.e., only a tri-colour LED and a photoresistor. In order to make a flow-injection analysis (FIA) with the spectrometric detector even more accessible for those with a limited budget, we additionally describe a low-cost simplified syringe-pump-based FIA set-up (€625), the assembling of which requires no more than basic technical facilities. We used such a set-up to test the performance of the proposed spectrometric detector for flow-injection analyses. The tests proved its suitability for real-life applications. The design procedures are also described.

No MeSH data available.


Calibration graphs for calcium ions obtained for two repeated sets of measurements in the FIA system with the T-7xd7 coil or T-7xd16 coil.
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f10-sensors-07-00166: Calibration graphs for calcium ions obtained for two repeated sets of measurements in the FIA system with the T-7xd7 coil or T-7xd16 coil.

Mentions: The peak heights obtained for two repeated sets of measurements in the FIA system with the T-7xd7 coil and the T-7xd16 coil relating to the concentration of calcium ions are presented in Figure 10. Smooth, repeatable curves with a 3rd-order polynomial trend line as a good fit were obtained. The correlation coefficients (r) were high: between 0.9984 and 0.9994. The shorter mixing coil (T-7xd7) gave a higher sensitivity. A more in-depth analysis of the results proved the linear relation between the peak height and calcium-ion concentration up to 40 mg/L. The resulting equations of the calibration lines are as follows: y = 1.013 10-2 × -1.562 10-2 (r = 0.9981) and y = 9.911 10-3 × -1.570 10-2 (r = 0.9980) for the set up with the higher sensitivity and y = 8.493 10-3 × -1.123 10-2 (r = 0.9989) and y = 8.255 10-3 × -8.510 10-3 (r = 0.9979) for the set up with the lower sensitivity.


A Novel Type of Tri-Colour Light-Emitting-Diode-Based Spectrometric Detector for Low-Budget Flow-Injection Analysis
Calibration graphs for calcium ions obtained for two repeated sets of measurements in the FIA system with the T-7xd7 coil or T-7xd16 coil.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756699&req=5

f10-sensors-07-00166: Calibration graphs for calcium ions obtained for two repeated sets of measurements in the FIA system with the T-7xd7 coil or T-7xd16 coil.
Mentions: The peak heights obtained for two repeated sets of measurements in the FIA system with the T-7xd7 coil and the T-7xd16 coil relating to the concentration of calcium ions are presented in Figure 10. Smooth, repeatable curves with a 3rd-order polynomial trend line as a good fit were obtained. The correlation coefficients (r) were high: between 0.9984 and 0.9994. The shorter mixing coil (T-7xd7) gave a higher sensitivity. A more in-depth analysis of the results proved the linear relation between the peak height and calcium-ion concentration up to 40 mg/L. The resulting equations of the calibration lines are as follows: y = 1.013 10-2 × -1.562 10-2 (r = 0.9981) and y = 9.911 10-3 × -1.570 10-2 (r = 0.9980) for the set up with the higher sensitivity and y = 8.493 10-3 × -1.123 10-2 (r = 0.9989) and y = 8.255 10-3 × -8.510 10-3 (r = 0.9979) for the set up with the lower sensitivity.

View Article: PubMed Central

ABSTRACT

In this paper we describe a low-cost spectrometric detector that can be easily assembled in a laboratory for less than €80 with a minimal number of optical components and which has proved sensitive and flexible enough for real-life applications. The starting point for the idea to construct this small, compact low-cost spectrometric detector was the decision to use a tri-colour light-emitting diode (LED) of the red-green-blue (RGB) type as a light source with the objective of achieving some flexibility in the selection of the wavelength (430 nm, 565 nm, 625 nm) but avoiding the use of optical fibres. Due to the dislocation of the emitters of the different coloured light, the tri-colour LED-based detector required an optical geometry that differs from those that are described in literature. The proposed novel geometry, with a coil-type glass flow-through cell with up to four ascending turns, proved useful and fit for the purpose. The simplicity of the device means it requires a minimal number of optical components, i.e., only a tri-colour LED and a photoresistor. In order to make a flow-injection analysis (FIA) with the spectrometric detector even more accessible for those with a limited budget, we additionally describe a low-cost simplified syringe-pump-based FIA set-up (€625), the assembling of which requires no more than basic technical facilities. We used such a set-up to test the performance of the proposed spectrometric detector for flow-injection analyses. The tests proved its suitability for real-life applications. The design procedures are also described.

No MeSH data available.