Rapid Degradation of Propanil in Rice Crop Fields

Abstract

Propanil and its major degradation product, 3,4-dichloroaniline (DCA), were monitored in surface water and soil samples from two rice fields of the Ebre Delta area (Tarragona, Spain) following agricultural application. On-line solidphase extraction (SPE) (water) and Soxhlet extraction (soil) followed by liquid chromatography/diode array detection (LC/ DAD) were used for the trace determination of both compounds. Unequivocal confirmation/identification was conducted by using liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry, LC/APCI-MS (using negative and positive ionization modes). Concentrations of the herbicide propanil in water samples varied from 1.9 to 55.9 µg/L. Propanil degraded very rapidly to DCA, and high concentrations of this product were found, varying from 16.5 to 470 µg/L in water and 119 ( 22 µg/kg in soil samples. No detectable DCA (<0.001%) was found in the applied pesticide formulation, indicating that DCA formation took place after propanil application. These field results compared favorably with laboratory experiments showing that humic interactions had a strong influence on the pesticide degradation. The half-lifes under real conditions for propanil and DCA, calculated using a first-order decay, were 1.2 and 1.6 days, respectively.

Substâncias húmicas de turfa: estudo dos parâmetros que influenciam no processo de extração alcalina

“…Devido suas características estruturais as SH podem interagir com metais 6,7 e compostos orgânicos como por exemplo, pesticidas e herbicidas presentes no ambiente [8][9][10] . Neste trabalho estudaram-se os parâmetros que influenciam na extração alcalina de SH de turfa como, tipo de extrator alcalino, concentração, tempo, temperatura de extração, razão turfa/extrator e granulometria da amostra.…”

“…Devido suas características estruturais as SH podem interagir com metais 6,7 e compostos orgânicos como por exemplo, pesticidas e herbicidas presentes no ambiente [8][9][10] . Para melhor compreender o comportamento das SH, estas têm sido estudadas sob diferentes aspectos: caracterização de estruturas parciais 11 , determinação de constantes de equilíbrio de espécies metal-SH 12 , labilidade relativa de metais 13 etc.. Entretanto, a primeira etapa para esses estudos é a extração das SH.…”

“…Possuem alto teor de grupos funcionais contendo oxigênio na forma de carboxilas, hidroxilas fenólicas e carbonilas 5 . Operacionalmente as SH são fracionadas em função de sua solubilidade a diferentes valores de pH em: ácidos húmicos )m ), ácidos fúlvicos (AF) e humina.Devido suas características estruturais as SH podem interagir com metais 6,7 e compostos orgânicos como por exemplo, pesticidas e herbicidas presentes no ambiente [8][9][10] . Neste trabalho estudaram-se os parâmetros que influenciam na extração alcalina de SH de turfa como, tipo de extrator alcalino, concentração, tempo, temperatura de extração, razão turfa/extrator e granulometria da amostra.…”

Herbicides Persistence in Rice Paddy Water in Southern Brazil

“…It is a post-emergent selective herbicide of contact with short duration used to control the electron transport inhibition of photosynthesis in herbs of wide leaves (Tomlin, 2007). According to Barceló et al (1998) it was also one of the most used in Tarragosa (Spain) and according to Coupe et al (1998) it was extensively used in the area of the Mississipi Delta (USA). Various studies have pointed out that propanil is degraded quickly into 3,4-dichloroaniline (3,4-DCA) (Dahchour et al, 1986;Correa & Steen, 1995;Barceló & Hennion, 1997).…”

Determination of Deltamethrin in Mice Plasma and Immune Organs by Simple Reversed-Phase HPLC

“…High-performance liquid chromatography (HPLC) is preferred with various detection systems including ultraviolet (UV) [20][21][22][23], diode array detection (DAD) [23][24][25][26], MS [27,28] and tandem mass spectrometry (MS n ) [29], and fluorescence detection (FLD) [30]. Generally, LC-MS techniques are considered superior to all the above-mentioned detection techniques, in terms of specificity and sensitivity.…”