Non-targeted impact of cyantraniliprole residues on soil quality, mechanism of residue degradation, and isolation of potential bacteria for its bioremediation.

Cyantraniliprole (CY), an anthranilic diamide insecticide widely used in grape farming for controlling various sucking pests, poses ecological concerns, particularly when applied as soil drenching due to the formation of more toxic and persistent metabolites. This study established the dissipation and degradation mechanisms of CY in grape rhizosphere soil using high-resolution Orbitrap-LC/MS analysis. The persistence of CY residues beyond 60 days was observed, with dissipation following biphasic first + first-order kinetics and a half-life of 15 to 21 days. The degradation mechanism of CY in the soil was elucidated, with identified metabolites such as IN-J9Z38, IN-JCZ38, IN-N7B69, and IN-QKV54. Notably, CY was found to predominantly convert to the highly persistent metabolite IN-J9Z38, raising environmental concerns. The impact of CY residues on soil enzyme activity was investigated, revealing a negative effect on dehydrogenase, alkaline phosphatase, and acid phosphatase activity, indicating significant implications for phosphorous mineralization and soil health. Furthermore, bacterial isolates were obtained from CY-enriched soil, with five isolates (CY3, CY4, CY9, CY11, and CY20) demonstrating substantial degradation potential, ranging from 66 to 92% of CY residues. These results indicate that the identified bacteria hold potential for commercial use in addressing pesticide residue contamination in soil through bioremediation techniques.

Assessment of degradation mechanism of imidacloprid residues in grape rhizosphere soil by UHPLC-Orbitrap™-MS and its residual impact on soil enzyme activity.

Imidacloprid (IM) is a systemic insecticide persistent in the environment and possesses a negative impact on the non-targeted ecosystem. The objective of the present study was to evaluate the dissipation and degradation mechanism of IM residues in grape rhizosphere soil and to investigate its residual effect on soil enzyme activity at different IM spiking levels. The half-life of IM residue in soil was 27, 36, and 43.5 days at a spiking level of 1, 10, and 50 mg kg-1, respectively following a bi-phasic first + first-order dissipation kinetics. UHPLC-Orbitrap™-MS analysis by targeted metabolomics approach revealed that IM metabolites such as IM-amine analogue, guanidine (reduction), 5-hydroxy IM (hydroxylation), IM-Urea (oxidation), reduced NO analogue of IM (oxidation), and olefin of guanidine IM (dehydrogenation) were identified and proposed the degradation mechanism in grape rhizosphere soil. Toxicity of IM residues on five extracellular enzymes, viz., dehydrogenase, acid phosphatase, alkaline phosphatase, ß-glucosidase, and urease revealed that activity of dehydrogenase, acid phosphatase, and alkaline phosphatase remained unaffected at 60th day of sampling. The ß-glucosidase and urease were negatively affected throughout the incubation period indicating the influence of IM residues on carbon and nitrogen mineralization in soil. Thus, long-term exposure of IM to grape rhizosphere through soil drenching could affect soil enzyme activity which has a negative effect on the soil nutrient cycle and soil microbiome.

Multiresidue analysis of pesticides in three Indian soils: method development and validation using gas chromatography tandem mass spectrometry.

The paper reports a multiresidue method that was validated on 220 multi-class pesticides in three major Indian soils, namely, (i) new alluvial soil (NAS); (ii) red lateritic soil (RS) and (iii) black soil (BS) from three different regions. An ethyl acetate-based extraction method with a freezing-out cleanup step was employed for sample preparation, followed by gas chromatography-tandem mass spectrometric analysis. The method that was initially optimized on BS worked satisfactorily for the other two soil matrices. At the spiking level of 10 µg/kg (LOQ), the recoveries were satisfactory (within 70-120%) with precision-RSDs, ≤20% (n = 6) for 85, 88.6, and 89% of compounds in BS, RS, and NAS respectively. At 20 µg/kg, the method performance was satisfactory in each soil for all pesticides. When this validated method was applied to analyse 25 field samples, 6 pesticides were detected in them. In each case, precision (RSD) was <20%. The method sensitivity, accuracy and precision complied with the SANTE/2020/12830 guidelines. The method can be applied for environmental monitoring and risk assessment purposes, thus aiding in regulating pesticide usage in agricultural fields. The limitations and future scope of the study are also discussed.HighlightsA multiresidue method is reported for simultaneous analysis of multi-class pesticides in diverse soilsThe method was validated on 220 pesticides in new alluvial, red lateritic and black soilsSample preparation involved extraction with ethyl acetate and cleanup by a freezing stepThe residues were estimated by gas chromatography tandem mass spectrometry (GC-MS/MS)The method accuracy and precision complied with the EU's SANTE guidelines.

Multiresidue analysis of pesticides in four different pomegranate cultivars: Investigating matrix effect variability by GC-MS/MS and LC-MS/MS.

Matrix effect (ME) is unavoidable in multiresidue pesticide analysis, even when using highly advanced instruments, and differences in MEs can affect residue analytical accuracy due to pomegranate cultivar composition variations. However, literature to support this claim is limited.The study used GC-MS/MS and LC-MS/MS to investigate four different Indian pomegranate cultivar extracts and their MEs on multi-class pesticides.The whole fruit and arils of all cultivarswere tested for 22 GC-amenable and 21 LC-amenable pesticides. Principal component analysis of the data confirmed that each cultivar had unique MEs for each pesticide.The majority of pesticides showed acute variations in recovery rates with 95% confidence, while GC-MS/MS-amenablepesticides showed more variation. Although extrapolative dilution reduced the influence of MEs on analytical accuracy, a generalized matrix-matching for all cultivars was not possible to achieve.To reduce the variability in MEs, it is recommended that a cultivar-specific matrix-matched standard should be used.

Development and validation of an analytical method for the multiresidue analysis of pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry.

For the first time, an analytical method for the multiresidue analysis of multiclass pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry (LC-MS/MS and GC-MS/MS) was developed and validated. At first, the sample was comminuted after adding water (1:2 w/v). The sample preparation workflow included acetonitrile extraction, followed by freeze-out of the extract at -80°C with a subsequent cleanup by dispersive solid phase extraction (dSPE) (100 mg of C18 + 150 mg of MgSO4 for LC-MS/MS and 100 mg of C18 + 25 mg florisil + 150 mg of MgSO4 for GC-MS/MS). As noted, these cleanup steps were quite effective in removing the fatty co-extractives. The optimised sample preparation method effectively minimised the matrix effects and offered a limit of quantification (LOQ) of 0.01 mg/kg for most compounds. The LC-MS/MS and GC-MS/MS methods were validated at three levels (0.01, 0.02 and 0.05 mg/kg) for 222 and 220 compounds respectively. The method accuracy and precision complied with the performance criteria of the SANTE/12682/2019 analytical quality control procedure. The results of the intra-laboratory (involving six analysts) and inter-laboratory studies (involving eight accredited laboratories) were comparable for all pesticides. Considering its performance efficiency and alignment with the regulatory guidelines, this method can be implemented across the food testing laboratories for the monitoring of pesticide residues in sesame seeds.