ABSTRACT
A modified and miniaturized SweEt/QuEChERS method for pesticide residue analysis applied to vine leaves is presented. The deep-frozen plant material was cryogenically processed. A 2 g analytical portion was hydrated for 30 min and extracted with acidified ethyl acetate after buffering with NaHCO3 and adding Na2SO4. A dispersive solid-phase (d-SPE) cleanup step with primary-secondary amine (PSA) was performed. The pesticide residues were determined using GC-MS/MS. The whole procedure was validated for 54-59 pesticides at 0.01, 0.02, 0.1, and 0.2 mg/kg in fresh vine leaves ( Vitis vinifera). The key method performance parameters investigated were specificity, linearity, trueness, within laboratory repeatability and reproducibility, limit of detection, limit of quantitation, and matrix effects. Recoveries for the 59 pesticides tested ranged from 60 to 110%, and the RSDs were lower than 20% for the majority of the pesticides studied.
Subject(s)
Chromatography, Gas/methods , Pesticide Residues/chemistry , Tandem Mass Spectrometry/methods , Vitis/chemistry , Plant Leaves/chemistry , Sensitivity and SpecificityABSTRACT
Dioxins (PCDD/Fs) are persistent organic pollutants. Their accumulation in soil is a crucial step in their transmission through the ecosystem. Traceability of dioxin in soil was evaluated in four sites A, B, C and D considered as potential industrial PCDD/Fs sources in Syria. Our results showed that the highest pollution with dioxin (⩾50 ppt) was found in site C (vicinity of Homs refinery). In parallel, analysis of physicochemical proprieties and bacterial density of soil samples were carried out. Bacterial density differed significantly among samples between 68×10(4) and 64×10(6) CFU g(-1)DW. Analysis of 16S rRNA encoding sequences showed that the genus Bacillus was the most abundant (74.7%) in all samples, followed by the genera Arthrobacter and Klebsiella with 5.2% and 4.7%, respectively. The genera Microbacterium, Pantoea, Pseudomonas, Enterobacter and Exiguobacterium formed between 2.1% and 2.6%. Cellulomonas, Kocuria, Lysinibacillus, Staphylococcus and Streptomyces were in a minority (0.5-1%). The bacterial richness and biodiversity, estimated by DMg and H' index, were highest in the heavily polluted site. Molecular screening for angular dioxygenase (AD α-subunit) and the cytochrome P450 (CYPBM3) genes, led to identification of 41 strains as AD-positive and 31 strains as CYPBM3-positive. RT-real-time PCR analysis showed a significant abundance of AD α-subunit transcript in the heavily dioxin-polluted soils, while the expression of CYPBM3 was highest in the moderately polluted soils. Our results illustrate the microbial diversity and functionality in soil exposed to dioxin pollution. Identification of dioxin-degrading bacteria from polluted sites should allow bioremediation to be carried out.
Subject(s)
Bacteria/drug effects , Furans/toxicity , Polychlorinated Dibenzodioxins/analogs & derivatives , Soil Microbiology , Soil Pollutants/toxicity , Bacteria/genetics , Bacteria/metabolism , Bacterial Proteins/genetics , Biodegradation, Environmental , Biodiversity , Cytochrome P-450 Enzyme System/genetics , Ecotoxicology , Furans/analysis , Gene Expression Regulation, Bacterial/drug effects , Polychlorinated Dibenzodioxins/analysis , Polychlorinated Dibenzodioxins/metabolism , Polychlorinated Dibenzodioxins/toxicity , Soil/chemistry , Soil Pollutants/analysis , Soil Pollutants/metabolismABSTRACT
Sesbania grandiflora (L.) pers (Fabaceae) and Arabidopsis thaliana (L.) (Brassicaceae) were genetically engineered to constitutively express the rabbit cytochrome p450 2E1 enzyme aiming at increasing their activity toward trichloroethylene (TCE) and dichlorodiphenyltrichloroethane (DDT) removal Successful generation of Sesbania and Arabidopsis transgenic plants was verified using p450 2E1 specific PCR and confirmed by western blot analysis. Gas chromatography (GC) analysis revealed that small cuttings of Sesbania and third generation (F3) Arabidopsis transgenic plants exposed to TCE and DDT in small hydroponics' vessels accumulated more TCE and DDT compared to plants transformed with the empty vector. Furthermore, both transgenic plants were more effective in breaking down TCE and DDT with a 2-fold increase in TCE metabolism. Two independent Arabidopsis lines showed that DDT was metabolized about 4-fold higher than that detected in non transformed plants. Similarly, S. grandiflora cuttings removed 51 to 90% of the added DDT compared with only 3% removal in controls transformed with the null vector. Notably, stability of rabbit cytochrome p450 2E1 was confirmed using third generation Arabidopsis plants that displayed higher potential for the removal of two important pollutants, TCE and DDT compared with the controls.
