Determination of Chlorinated Anilines Residues in Soil by Gas Chromatography-Triple Quadrupole Mass Spectrometry Coupled with Solid Phase Microextraction / 分析化学

A gas chromatography-triple quadrupole mass spectrometry coupled with solid phase microextraction method ( SPME-GC/QQQ) was developed for the determination of chlorinated anilines ( CAs) residues in soil. The multi-reaction monitoring ( MRM ) parameters were optimized. The SPME conditions such as amount of soil sample, volume of added water, extraction temperature and absorption time were investigated. Optimum SPME conditions including 8 g of soil sample, 4 mL of water, 80℃ of extraction temperature and 40 min of absorption time were employed in the experiment. Method detection limits were within the range of 1-10 pg/g, while linearities were within the range of 5-1000 pg/g. Under the optimized conditions, the soil samples spiked with 200 pg/g targets were determined with recoveries of 96. 8%-144. 2%and relative standard deviations of 13 . 4%-27 . 8% ( n=5 ) . The proposed method combines simplicity and rapidity of SPME and high selectivity of MRM. It is especially suitable for the quick screening and determination of trace amounts of chlorinated anilines residues in soil.

Effect of Para Substituted Anilines Chemical Structure on Methane Biosynthesis by the Methanogens.

The present paper aims to study the effect of aromatic structure on the inhibition of biogas production and more specifically the effect of para substituted anilines functional groups (chemical structure) on methane biosynthesis by the digested pig manure methanogens. The objective of this study was also to examine the structure-toxicity relationships of aromatic compounds to acetoclastic methanogens. Study Design: Anaerobic digestion of pig manure, anaerobic toxicity essay, The effects of functional group nature on inhibition of methane production by acetoclastic methanogens. Correlation of the methanogenic toxicity (IC50) with aromatic compounds hydrophobicity (logPoct). Place and Duration of Study: Department of Chemistry, University of Kinshasa (DR Congo), between August 2011 and May 2012. Methodology: The toxicity to acetoclastic methanogenic bacteria was performed with the standard method of serum bottles, digested pig manure was utilized as inoculums, acetate as substrate and the methane gas volume produced was measured by serum bottles liquid displacement systems (Mariotte flask system). Results: The obtained results indicate that relationships exist between para substituted anilines functional groups nature (chemical structure) and their inhibitory effects on methanogens. The toxicity of para bisubstituted anilines increases in the following order: SO3 < OH < H < CH3 < Cl < NO2 From this sequence of increasing toxicity, it can be seen that the methanogenic toxicity varies with the functional group nature which is in the para position of the main function. Indeed, p-Nitroaniline and benzene with 45.76 and 208.78 mg/l as IC50 values respectively were the most toxic compounds, while p-Aminophenol and p-Aminosulfonic acid (Sulfanilic acid) with 1800.39 and 2777.82 mg/l IC50 values were the less toxic. A very significant negative linear correlation between the toxicity of para substituted anilines compounds and their hydrophobicity was found. Conclusion: The results of this study indicate that relationships exist between para substituted anilines functional groups nature and their inhibitory effects in methane biosynthesis by the methanogens.

Quantitative stuucture-activity relationships t predict in vitro teac and ec500 of synthetic anilines / Relacionescuantiitativas actividad-estructura para predeci la teac y la eec50 de anilinas sintéticas / Relaçõs quantitaativas atividade - estrutura para a predição a teaceaec50 da anilinas sintéticas

Quantitative Structure-Activity Relationships (QSAR) are useful in understanding how chemical structure relates to the biological activity of natural or synthetic compounds and for designing newer and better compounds. In the present study, 22 N-arylmethyl substituted anilines were treated with ABTS (2,2'-azinobis- (3-ethylbenzothiazoline-6-sulfonic-acid)) and DPPH (2,2-diphenyl-1-picrylhy-dracyl) radicals in order to evaluate their TEAC (mmol trolox/mmol antioxidant, Trolox Equivalent Antioxidant Capacity) and EC50 (mmol antioxidant/mmol initial DPPH, Antioxidant Equivalent Concentration to decrease the initial DPPH concentration by 50 %) values, respectively. Different QSARs were developed based on these data, using theoretical descriptors derived from geometry-optimized molecular structures. A model with electronic energy (EE), total charge weighted partial positively charged surface area (PPSA-2), and exact polarizability (αzz) as descriptors showed satisfactory predictive TEAC performance according to internal and external validation procedures. It can be useful in predicting data and setting a testing priority for those compounds not yet synthesized or for which experimental data are not available.

Las relaciones cuantitativas actividad-estructura (QSAR) son útiles para entender la forma en que la estructura química de sustancias sintéticas y naturales se relaciona con la actividad biológica, y para el diseño de nuevos y mejores compuestos. En el presente estudio fueron evaluadas las capacidades de 22 anilinas N-arylmetil sustituidas para la captura de los radicales ABTS (ácido 2,2'-azino-bis(3-etilbenzo-tiazolino-6-sulfónico) y DPPH (2,2-difenil-1-picrilhidracilo), relacionadas con los valores de TEAC (mmol trolox/mmol antioxidante, capacidad antioxidante equivalente al Trolox) y EC50 (concentración equivalente de antioxidante para disminui r la concentración inicial de DPPH enun 50%), respectivamente. Las TEAC, las EC50 y los descriptores teóricos derivados de las estructuras moleculares optimizadas fueron utilizados para elaborar las diferentes QSAR. Los modelos TEAC con descriptores como EE (energía electrónica), PPSA-2 (carga total pesada con el área superficial cargada positivamente) y αzz (polarizabilidad exacta) mostraron una capacidad de predicción satisfactoria por procedimientos de validación interna y externa, por lo que pueden ser útiles para la predicción de actividades de compuestos que aún no han sido sintetizados o con datos experimentales no disponibles.

Relaçãos quantitativa atividade - estrutura tem sido empregado para estabelecer se a estrutura química está relacionada com a atividade biológica dos químicos naturais e sintéticos e para o desenho de novos e melhores compostos. No presente estudo foram avaliadas as capacidades de 22 anilinas N-arylmetil sustituidas para a captura dos radicais de ABTS (ácido-2,2'-azino-bis(3-etilo-benzo-tiazolino-6-sulfônic o) e DPPH (2,2-difenilo-1-picrilhidracilo), relacionadas com os valores de TEAC (mmol trolox/mmol antioxidante, capacidade antioxidante equivalente ao Trolox) yEC50 (concentração equivalente de antioxidante para a diminuição da concentração inicial de DPPH para um 50 %) respectivamente. As TEAC, as EC50 eos descritores teóricos derivados das estruturas moleculares otimizadas foram empregados para elaborar as diferentes QSARs. Os modelos TEAC com descritores como EE (Energia Eletrônica), PPSA-2 (carga total pesada com a área superficial carregada positivamente) y αzz (polarizabilidade exata) mostraram uma satisfatória capacidade de predição pelos procedimentos de validação interna e externa, e por tanto podem ser úteis para a predição da capacidade antioxidante de compostos que ainda no tem sido sintetizados com dados experimentais não disponíveis.