Implementación de un método analítico de aplicación forense para el escrutinio de plaguicidas en agua
Fecha
2011-03
Autores
Calvo González, Francisco
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Editor
Universidad Nacional (Costa Rica)
Resumen
El desarrollo de una agricultura a mayor escala ha implicado un cambio en la modalidad de producción, favoreciéndose la implantación del monocultivo, y con ello el desarrollo de plagas agrícolas.
Debido a la necesidad de controlar las plagas se desarrollaron los plaguicidas, sin embargo, por el mal manejo de éstos, su uso indebido y excesivo, se han presentado problemas ambientales, como es el caso de la contaminación de mantos acuíferos utilizados para el consumo humano, la pesca masiva y la contaminación de aguas superficiales; situaciones que han provocado el incremento en el número de denuncias por contaminación con plaguicidas ante las Fiscalías, las que para su resolución, requieren la evaluación científica de la evidencia física a través de un ente aprobado por la Corte Suprema de Justicia, como es la Unidad Ambiental Forense del Departamento de Ciencias Forenses. Para subsanar esta necesidad, se desarrolló el análisis para cinco plaguicidas en aguas superficiales, siendo ellos el etoprofós, terbufós, ametrina, clorpirifós y la cipermetrina. En el desarrollo del método de análisis se empleó un cromatógrafo de gases con detector de masas (GC-MSD) utilizando el método de adquisición de datos SCAN, y un cromatógrafo de gases con doble detector de nitrógeno y fósforo (GC-NPD/NPD). Para la extracción de los plaguicidas de la muestra de agua se utilizó la técnica de SPE con el cartucho Envi-Chrom P de estirenodivinilbenceno.
Como parámetros de desempeño del método de análisis instrumental se utilizó, en primer término, la linealidad obteniendo muy buenos resultados para cada uno de los plaguicidas trabajados, cumpliendo con los estimadores estadísticos de R2 y FANWA. Además, se evaluó la homocedasticidad o heterocedasticidad de la respuesta del detector para cada uno de los analitos; los sistemas de detección utilizados no presentaron preferencia hacia uno u otro comportamiento. Para el GC-MSD no se presentó reproducibilidad para la pendiente, misma situación ocurrió con el GC-NPD/NPD con la excepción del terbufós. Se probó que la sensibilidad para el GC-NPD/NPD es hasta un orden de magnitud mayor para los analitos utilizados que con el GC-MSD. Se obtuvieron bajos niveles de detección y cuantificación utilizando el GC-NPD/NPD, mientras que para el GC-MSD, los niveles son altos.
Las pruebas de recuperación para la mezcla de plaguicidas, tanto en agua de laboratorio como en una muestra de agua real fueron cercanas al 100 0/0, con excepción del terbufós.
Con el desarrollo de esta metodología se dotó a la Unidad Ambiental Forense de un método de análisis para plaguicidas, mediante una técnica sencilla, que utiliza poco solvente y es rápida para el trabajo en el laboratorio.
The development of agriculture on a larger scale has implied a change in the modality of production, favoring the implementation of monoculture, and with it the development of agricultural pests. Due to the need to control pests, pesticides were developed, however, due to their mismanagement, improper and excessive use, environmental problems have arisen, such as the contamination of aquifers used for human consumption. , massive fishing and contamination of surface waters; situations that have caused an increase in the number of complaints for pesticide contamination before the Prosecutor's Offices, which for their resolution require the scientific evaluation of the physical evidence through an entity approved by the Supreme Court of Justice, such as the Unit Forensic Environmental Department of Forensic Sciences. To address this need, the analysis for five pesticides in surface waters was developed, being ethoprofos, terbufos, ametrin, chlorpyrifos and cypermethrin. In the development of the analysis method, a gas chromatograph with a mass detector (GC-MSD) was used using the SCAN data acquisition method, and a gas chromatograph with a double nitrogen and phosphorus detector (GC-NPD/NPD). . For the extraction of pesticides from the water sample, the SPE technique was used with the Envi-Chrom P cartridge of styrenedivinylbenzene. As performance parameters of the instrumental analysis method, linearity was used, firstly, obtaining very good results for each of the pesticides worked, complying with the statistical estimators of R2 and FANWA. In addition, the homoscedasticity or heteroscedasticity of the detector response was evaluated for each of the analytes; the detection systems used did not present a preference towards one behavior or the other. For the GC-MSD, there was no reproducibility for the slope, the same situation occurred with the GC-NPD/NPD with the exception of terbufos. The sensitivity for the GC-NPD/NPD was proven to be up to an order of magnitude higher for the analytes used than with the GC-MSD. Low levels of detection and quantification were obtained using the GC-NPD/NPD, while for the GC-MSD, the levels are high. Recovery tests for the pesticide mixture, both in laboratory water and in a real water sample were close to 100 0/0, with the exception of terbufos. With the development of this methodology, the Forensic Environmental Unit was provided with a method of analysis for pesticides, using a simple technique that uses little solvent and is quick to work in the laboratory.
The development of agriculture on a larger scale has implied a change in the modality of production, favoring the implementation of monoculture, and with it the development of agricultural pests. Due to the need to control pests, pesticides were developed, however, due to their mismanagement, improper and excessive use, environmental problems have arisen, such as the contamination of aquifers used for human consumption. , massive fishing and contamination of surface waters; situations that have caused an increase in the number of complaints for pesticide contamination before the Prosecutor's Offices, which for their resolution require the scientific evaluation of the physical evidence through an entity approved by the Supreme Court of Justice, such as the Unit Forensic Environmental Department of Forensic Sciences. To address this need, the analysis for five pesticides in surface waters was developed, being ethoprofos, terbufos, ametrin, chlorpyrifos and cypermethrin. In the development of the analysis method, a gas chromatograph with a mass detector (GC-MSD) was used using the SCAN data acquisition method, and a gas chromatograph with a double nitrogen and phosphorus detector (GC-NPD/NPD). . For the extraction of pesticides from the water sample, the SPE technique was used with the Envi-Chrom P cartridge of styrenedivinylbenzene. As performance parameters of the instrumental analysis method, linearity was used, firstly, obtaining very good results for each of the pesticides worked, complying with the statistical estimators of R2 and FANWA. In addition, the homoscedasticity or heteroscedasticity of the detector response was evaluated for each of the analytes; the detection systems used did not present a preference towards one behavior or the other. For the GC-MSD, there was no reproducibility for the slope, the same situation occurred with the GC-NPD/NPD with the exception of terbufos. The sensitivity for the GC-NPD/NPD was proven to be up to an order of magnitude higher for the analytes used than with the GC-MSD. Low levels of detection and quantification were obtained using the GC-NPD/NPD, while for the GC-MSD, the levels are high. Recovery tests for the pesticide mixture, both in laboratory water and in a real water sample were close to 100 0/0, with the exception of terbufos. With the development of this methodology, the Forensic Environmental Unit was provided with a method of analysis for pesticides, using a simple technique that uses little solvent and is quick to work in the laboratory.
Descripción
Calvo González, F. (2011). Implementación de un método analítico de aplicación forense para el escrutinio de plaguicidas en agua. [Tesis de Licenciatura]. Universidad Nacional, Heredia, C. R.
Palabras clave
CONTAMINACION DEL AGUA, WATER CONTAMINATION, PLAGUICIDAS, PESTICIDES, ANALISIS QUIMICO, MUESTREO, SAN RAFAEL (HEREDIA)