Extraction of pesticides from soil using supercritical carbon dioxide added with methanol as co-solvent

Insights into the recent advances in nano-bioremediation of pesticides from the contaminated soil

In the present scenario, the uncontrolled and irrational use of pesticides is affecting the environment, agriculture and livelihood worldwide. The excessive application of pesticides for better production of crops and to maintain sufficient food production is leading to cause many serious environmental issues such as soil pollution, water pollution and also affecting the food chain. The efficient management of pesticide use and remediation of pesticide-contaminated soil is one of the most significant challenges to overcome. The efficiency of the current methods of biodegradation of pesticides using different microbes and enzymes depends on the various physical and chemical conditions of the soil and they have certain limitations. Hence, a novel strategy is the need of the hour to safeguard the ecosystem from the serious environmental hazard. In recent years, the application of nanomaterials has drawn attention in many areas due to their unique properties of small size and increased surface area. Nanotechnology is considered to be a promising and effective technology in various bioremediation processes and provides many significant benefits for improving the environmental technologies using nanomaterials with efficient performance. The present article focuses on and discusses the role, application and importance of nano-bioremediation of pesticides and toxic pollutants to explore the potential of nanomaterials in the bioremediation of hazardous compounds from the environment.

Optimization and validation of a QuEChERS-based method for the simultaneous environmental monitoring of 218 pesticide residues in clay loam soil

A modified QuEChERS method was optimized, validated and verified for the extraction of 218 pesticide residues in agricultural soil samples. The 218 analytes are extracted using a single step, without clean-up, with matrix-matched calibration, and two complementary techniques: liquid and gas chromatography tandem triple quad mass spectrometry (LC-MS/MS and GC-MS/MS). Some of the parameters such as salts, acidity of the extraction solvent, sample moisture and some mechanical changes in the procedure were optimized to improve the overall performance for the target compounds and the soil matrix. The method was fully validated on a representative agricultural soil sample of the Canary Islands (clay loam soil) in terms of linearity, accuracy and precision. To avoid matrix effects, matrix-matched calibration curves (R² ≥ 0.99) were used for all target analytes. 100% of the compounds can be quantified with limits of quantification (LOQ) lower than the limit typically used in soils (50 ng g^-1), with 92% of compounds presenting a LOQ that is at least 10 times lower than that normally required. The limits of detection (LOD) ranged between 0.024 and 6.25 ng g^-1. The validated method was applied to a series of actual samples of agricultural soil (n = 18). In addition, as a further verification of its potential, the results of the application of the method in the investigation of clay loam soil samples that were obtained from underneath wildlife carcasses in the context of an environmental forensic investigation are also presented.

Optimization of supercritical fluid extraction method for detection of fluquinconazole and tetraconazole in soil using gas chromatography and confirmation using GC-MS: application to dissipation kinetics

The aim of this study was to establish an analytical method to detect fluquinconazole and tetraconazole in soil using supercritical fluid extraction (SFE) and gas chromatography (GC). The optimal extraction conditions for SFE were: temperature, 60 °C; pressure, 280 kg/cm(2) ; extraction time, 50 min; and a 10% modifier ratio. The linearity of the calibration curves was good and yielded a determination coefficient (R(2) ) ≥ 0.995. The soil samples were fortified with known quantities of the analytes at three different concentrations (0.01, 0.02 and 0.1 µg/g for fluquinconazole; 0.05, 0.1 and 0.5 µg/g for tetraconazole), and the recoveries ranged between 83.7 and 94.1%. The intra- and inter-day relative standard deviations were 1.3-10.6 and 2.2-11.9% for fluquinconazole and tetraconazole, respectively. The limit of detection and limit of quantitation were 0.002 and 0.01 µg/g for fluquinconazole and 0.01 and 0.05 for tetraconazole, respectively. The method was successfully applied to the analysis of soil residues collected from an onion field. The results show that a combination of SFE and GC can be used as an environmentally friendly technique to detect fungicides in soil.

Determination of isotianil in brown rice and soil using supercritical fluid extraction and gas chromatography/mass spectrometry

Isotianil (3,4-dichloro-2'-cyano-1,2-thiazole-5-carboxanilide) is a new plant-activating pesticide. Usage of the pesticide was approved for rice fields in 2010 and its production increased 400 times (2 × 10(4) kg) in the next year. In this work, a method for determining isotianil in brown rice and rice field soil was investigated for the first time. Isotianil was extracted by supercritical fluid extraction and measured by gas chromatography/mass spectrometry. Isotianil was successfully analyzed with good recoveries (95.1-99.3%) even from soil samples with strong adsorption of pesticides.