Uso de glucosa como agente reductor en la determinación semicuantitativa de paraquat en orina
n°13 [jun-dic 2007] Retel18/12/2007
José Rafael Luna1, María Luisa Di Bernardo2, María Ysabel García2, Carlos Yánez3, Richard Mejias3, Alexis Morales1, Lester Rodríguez3, Fernando Ovalles2
1*. MSc. en Química Aplicada de
2. Dr. en Química Analítica de la Universidad de Los Andes, Mérida-Venezuela.
3. Farmacéutico de
2. Dr. en Química Analítica de la Universidad de Los Andes, Mérida-Venezuela.
3. Farmacéutico de
Resumen
El paraquat, es un herbicida, que ejerce su acción interfiriendo con el proceso de fotosíntesis, es de acción rápida, y en el ser humano es altamente toxico. La ruta de absorción mas importante es la digestiva, estando involucrado en casos de intoxicación voluntaria e involuntaria. Los efectos toxicológicos del paraquat varían según la cantidad ingerida y su determinación sirve para medir el riesgo de letalidad del paciente. En la emergencia hospitalaria se emplean métodos cualitativos para la determinación de paraquat, que revelan la concentración de la dosis ingerida según la intensidad del color, siendo la alternativa mas acertada para el diagnostico presuntivo cuando se sospecha una intoxicación. En esta investigación se reprodujo el método del ditionito de sodio, comprobándose la inestabilidad del complejo coloreado al estar en contacto con el oxigeno, y se diseño un test semicuantitativo que consiste en el uso de glucosa como agente reductor del paraquat, observándose que la misma tiene ventajas sobre el ditionito como agente reductor, en vista de que la glucosa no pierde actividad con la luz ni con el oxígeno, es mas económica, no toxica y origina mayor estabilidad del cromógeno. El complejo coloreado se evidencia después de su incubación en baño de maría, con la finalidad de observar como varia la intensidad de color a diferentes concentraciones, siendo estable hasta más o menos doce horas; el test puede ser aplicado como prueba rápida en análisis de rutina en pacientes presuntamente intoxicados con paraquat.
Palabras claves: paraquat, orina, glucosa, ditionito.
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Palabras claves: paraquat, orina, glucosa, ditionito.
Ver archivo PDF (208 KB)
Abstract
Use of glucose as a reducing agent in the semi-quantitative determination of paraquat in urine samples
Paraquat belongs to the Bipyridylium family of herbicides. It is widely used for green weed control since interferes with the mechanism of photosynthesis. The absorption by the intact skin and the respiratory tract is lower than ingestion. Paraquat is highly toxic via ingestion. Precisely, oral administration with either suicidal intent or accidentally is by far the commonest route of entry. The acute toxicological effects depend on the amount ingested. The absorbed paraquat is distributed via the bloodstream to practically all organs and tissues of the body, but it is excreted rapidly by the kidney. In some cases, before prescribing a treatment for people poisoned by paraquat, a spot test may be needed in order to confirm its diagnosis. Survival depends on the accuracy and timeliness of the diagnosis. There is a known spot test for paraquat in the urine which is available on hospitals and emergency centers. This qualitative test is based on the reduction of paraquat to a blue complex in the presence of alkali and sodium dithionite. The main disadvantage of this test is the instability of the blue radical ion in presence of oxygen. In the present research the aforementioned urine color test was reproduced but substituting sodium dithionite by glucose. Glucose was used as reducing agent in order to develop a semi-quantitative method with competitive advantages over the official method. Glucose is cheap, stable and nontoxic. Paraquat reacts with glucose in alkaline medium to yield a blue chromogen with higher stability than that one obtained using sodium dithionite. The colored complex is formed after incubation in water bath. Results showed that the colored complex is stable up to 12 hours and is paraquat-glucose concentration dependent. The proposed qualitative method could be used as a rapid and routinely color test for paraquat in urine samples for a quick confirmation of paraquat poisoning.
Keywords: paraquat, urine, glucose, dithionite.
Download PDF (208 KB)
Paraquat belongs to the Bipyridylium family of herbicides. It is widely used for green weed control since interferes with the mechanism of photosynthesis. The absorption by the intact skin and the respiratory tract is lower than ingestion. Paraquat is highly toxic via ingestion. Precisely, oral administration with either suicidal intent or accidentally is by far the commonest route of entry. The acute toxicological effects depend on the amount ingested. The absorbed paraquat is distributed via the bloodstream to practically all organs and tissues of the body, but it is excreted rapidly by the kidney. In some cases, before prescribing a treatment for people poisoned by paraquat, a spot test may be needed in order to confirm its diagnosis. Survival depends on the accuracy and timeliness of the diagnosis. There is a known spot test for paraquat in the urine which is available on hospitals and emergency centers. This qualitative test is based on the reduction of paraquat to a blue complex in the presence of alkali and sodium dithionite. The main disadvantage of this test is the instability of the blue radical ion in presence of oxygen. In the present research the aforementioned urine color test was reproduced but substituting sodium dithionite by glucose. Glucose was used as reducing agent in order to develop a semi-quantitative method with competitive advantages over the official method. Glucose is cheap, stable and nontoxic. Paraquat reacts with glucose in alkaline medium to yield a blue chromogen with higher stability than that one obtained using sodium dithionite. The colored complex is formed after incubation in water bath. Results showed that the colored complex is stable up to 12 hours and is paraquat-glucose concentration dependent. The proposed qualitative method could be used as a rapid and routinely color test for paraquat in urine samples for a quick confirmation of paraquat poisoning.
Keywords: paraquat, urine, glucose, dithionite.
Download PDF (208 KB)