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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.

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FIAgrams obtained for different dye-injection volumes 8.3 μL (V1), 16.5 μL (V2), 24.8 μL (V3), 33.0 μL (V4) and 41.3 μL (V5), under selected experimental conditions as specified in the legend.
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f6-sensors-07-00166: FIAgrams obtained for different dye-injection volumes 8.3 μL (V1), 16.5 μL (V2), 24.8 μL (V3), 33.0 μL (V4) and 41.3 μL (V5), under selected experimental conditions as specified in the legend.

Mentions: The results, which are presented in Figure 5, proved that even though in its present form the FIA system with 1-mL syringe pumps has a maximum flow rate limited to 1.5 mL/min it allows for a wide variety of dispersion coefficients in the range of medium (D = 2−10) and large dispersions (D >10). The shapes of the peaks that were obtained for different dye-injection volumes, 8.3, 16.5, 24.8, 33.0 and 41.3 μL (V1-V5), under selected experimental conditions are presented in Figure 6. The peaks in magenta were obtained for the experimental series with the lowest dispersion (1.5 mL/min, 10a cell, no mixing coil), the peaks in green were obtained for the experimental series with the highest dispersion (0.5 mL/min, 10a cell, mixing coil, tubing length 35.2 cm) and the peaks in blue were obtained for the experimental series with moderate dispersion (0.5 mL/min, cell 12, no mixing coil). The shape of the peaks promises that low-cost data-acquisition devices with a limited data-point sampling rate are satisfactory.


A Novel Type of Tri-Colour Light-Emitting-Diode-Based Spectrometric Detector for Low-Budget Flow-Injection Analysis
FIAgrams obtained for different dye-injection volumes 8.3 μL (V1), 16.5 μL (V2), 24.8 μL (V3), 33.0 μL (V4) and 41.3 μL (V5), under selected experimental conditions as specified in the legend.
© Copyright Policy
Related In: Results  -  Collection

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

f6-sensors-07-00166: FIAgrams obtained for different dye-injection volumes 8.3 μL (V1), 16.5 μL (V2), 24.8 μL (V3), 33.0 μL (V4) and 41.3 μL (V5), under selected experimental conditions as specified in the legend.
Mentions: The results, which are presented in Figure 5, proved that even though in its present form the FIA system with 1-mL syringe pumps has a maximum flow rate limited to 1.5 mL/min it allows for a wide variety of dispersion coefficients in the range of medium (D = 2−10) and large dispersions (D >10). The shapes of the peaks that were obtained for different dye-injection volumes, 8.3, 16.5, 24.8, 33.0 and 41.3 μL (V1-V5), under selected experimental conditions are presented in Figure 6. The peaks in magenta were obtained for the experimental series with the lowest dispersion (1.5 mL/min, 10a cell, no mixing coil), the peaks in green were obtained for the experimental series with the highest dispersion (0.5 mL/min, 10a cell, mixing coil, tubing length 35.2 cm) and the peaks in blue were obtained for the experimental series with moderate dispersion (0.5 mL/min, cell 12, no mixing coil). The shape of the peaks promises that low-cost data-acquisition devices with a limited data-point sampling rate are satisfactory.

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.


Related in: MedlinePlus