ESPECTROSCOPIA RAMAN DE COSTO REDUCIDO PARA LA IDENTIFICACIÓN DE LÍQUIDOS TRANSPARENTES
Abstract
El trabajo presenta el desarrollo de un sistema de espectroscopia Raman de costo reducido (menor a 1000 USD), destinando a la detección de líquidos transparentes no identificables por métodos colorimétricos. Dadas las necesidades (en Bolivia) de control y fiscalización de compuestos químicos en productos locales e importados, el desarrollo de sistemas espectroscópicos moleculares se perfila como una solución accesible. El sistema desarrollado se basó en un espectrómetro clásico modificado, con una resolución de 2 nm y un ancho espectral de 200 nm. Para la generación de la dispersión Raman se usó un diodo láser de 405 nm y 5mW acoplado a un recipiente transparente y una lente auxiliar para la proyección de la luz sobre el plano de entrada. Como detector se usó una cámara CCD con refrigeración termoeléctrica, cuyas imágenes se integraron verticalmente para la obtención de los espectros. Como parte de las pruebas de validación, se obtuvieron espectros Raman de agua, etanol y acetato de etilo. Así mismo, se obtuvo el espectro de una mezcla de etanol y agua. En todos los casos se observó coincidencia entre los espectros obtenidos y los de referencia, validando su correcta detección. Como punto de mejora, se identificó la adición de filtros de corte específicos para mejorar el contraste y la resolución del sistema. Dados estos resultados, el sistema mostró un gran potencial como una herramienta analítica de bajo costo para compuestos moleculares.
This work presents the development of a low-cost Raman spectroscopy system, aimed at the detection of clear liquids that cannot be detected using colorimetric methods. Given the needs (in Bolivia) of control and inspection of chemical compounds in local and imported goods, the development of molecular spectroscopy systems is presented as an accessible solution. The developed system was based on a modified version of a classic spectrometer, with a measured spectral resolution of 2nm and a width of 200nm. A 405nm and 5mW laser diode, a clear cuvette with the sample, and an auxiliary lens were used for the generation of Raman scattering. The system used a thermoelectrically cooled CCD camera as the detector and its images were integrated vertically for spectrum extraction. As part of validation tests, Raman spectra of water, ethanol and ethyl acetate were obtained. Also, the system was able to get a Raman spectrum from a mix of ethanol and water. In every case, there was a coincidence between the obtained spectra and the references, showing a correct detection. After these results, the system showed great potential as low cost analytic tool for detecting molecular compounds. The results also showed that resolution and contrast could be improved by the use of specific cutoff filters in future versions of the system.
This work presents the development of a low-cost Raman spectroscopy system, aimed at the detection of clear liquids that cannot be detected using colorimetric methods. Given the needs (in Bolivia) of control and inspection of chemical compounds in local and imported goods, the development of molecular spectroscopy systems is presented as an accessible solution. The developed system was based on a modified version of a classic spectrometer, with a measured spectral resolution of 2nm and a width of 200nm. A 405nm and 5mW laser diode, a clear cuvette with the sample, and an auxiliary lens were used for the generation of Raman scattering. The system used a thermoelectrically cooled CCD camera as the detector and its images were integrated vertically for spectrum extraction. As part of validation tests, Raman spectra of water, ethanol and ethyl acetate were obtained. Also, the system was able to get a Raman spectrum from a mix of ethanol and water. In every case, there was a coincidence between the obtained spectra and the references, showing a correct detection. After these results, the system showed great potential as low cost analytic tool for detecting molecular compounds. The results also showed that resolution and contrast could be improved by the use of specific cutoff filters in future versions of the system.
Description
Vol. 19, No. 1