Dissipation dynamics and final residues of flutriafol in tobacco and soil using ultrasound-assisted extraction before liquid chromatography/tandem mass spectrometry

The dissipation dynamics and final residues of flutriafol on tobacco plant and soil were studied under field conditions. The residues of flutriafol in soil, green tobacco leaves and cured tobacco leaves were extracted by ultrasound-assisted extraction, cleaned up by dispersive solid-phase extraction and detected by liquid chromatography with tandem mass spectrometry. The limits of detection of flutriafol in soil, green tobacco leaves and cured tobacco leaves were 0.006, 0.033 and 0.033 mg·kg^?1, respectively. The limits of quantification of flutriafol in soil, green tobacco leaves and cured tobacco leaves were 0.02, 0.1 and 0.1 mg·kg^?1, respectively. Recoveries were 72.9–102% with relative standard deviations of less than 12% in soil and tobacco matrix. For field experiments, the half-lives of flutriafol in soil and green tobacco leaves were 9.2–11.5 and 9.5–11.1 days, respectively. At harvest, the final residue levels of flutriafol in cured tobacco leaves collected 21 days after one application at the recommended dosage were below 2.0 mg/kg. The maximum residue limit maximum residue limit (MRL) for flutriafol in tobacco has not yet been established in any countries. The data could help the Chinese Government to establish the MRL of flutriafol in tobacco and provide guidance on the proper use of flutriafol.     

Dissipation and residue fate of kresoxim-methyl in tobacco leaves and soil under field conditions

The fate of kresoxim-methyl was studied in a tobacco field ecosystem, and a simple and reliable method was developed for the determination of kresoxim-methyl in soil, green and cured tobacco leaves. Kresoxim-methyl residues were extracted from samples with petroleum ether, and determined by gas chromatography (GC) coupled with an electron capture detector (ECD). Kresoxim-methyl (30% suspension concentration) was applied at 150 g a.i. ha^–1 (the recommended high dosage) and 225 g a.i. ha^–1 (1.5 times the recommended high dosage) in the experimental fields in Huishui and Changsha in China. The limits of detection (LODs) and limits of quantification (LOQs) of kresoxim-methyl in green tobacco leaves, cured tobacco leaves and soil were 0.012 and 0.04 mg kg^–1, 0.12 and 0.4 mg kg^–1, and 0.0015 and 0.005 mg kg^–1, respectively. The average recoveries were 84.5% to 95.7%, 79.8% to 94.3% and 83.3% to 93.8% with relative standard deviations (RSDs) less than 10% in green tobacco leaves at four spiked levels (0.04, 0.2, 2 and 8 mg kg^–1), cured tobacco leaves at three spiked levels (0.4, 1 and 10 mg kg^–1) and soil at three spiked levels (0.005, 0.05 and 0.5 mg kg^–1), respectively. The results showed that the half-lives of kresoxim-methyl in green tobacco leaves and soil were 1.2–5.3 days and 6.7–10.4 days, respectively. At harvest, kresoxim-methyl residues in cured tobacco leaves samples collected 21 days after the last application at the recommended dosage were below 1.0 mg kg^–1. These results could help establish appropriate application frequency and harvest intervals in the use of kresoxim-methyl on tobacco plants.     

Dissipation rates of saisentong residues in fresh tobacco,tobacco powder and soil determined by high-performance liquid chromatography coupled with diode array detection

Two independent field trials were performed in Guizhou and Hunan, China in 2013 to investigate the dissipation and residue levels of saisentong in tobacco and soil. A novel and accurate method using high-performance liquid chromatography with diode array detection was developed and validated to determine saisentong levels in tobacco and soil. The average recovery of saisentong at fortification levels of 0.5, 2.5, 5.0 and 50.0 mg kg^?1 in fresh tobacco ranged from 75.92 to 107.40% with a relative standard deviation (RSD) of 0.94 to 7.55%, that at fortification levels of 0.5, 2.0 and 5.0 mg kg^?1 in tobacco powder ranged from 74.96 to 94.43% with a relative standard deviation (RSD) of 4.38 to 8.14%, and that at fortification levels of 0.1, 0.5 and 5.0 mg kg^?1 in soil ranged from 86.90 to 100.0% with an RSD of 1.38 to 4.62%. The limit of detection (LOD) of saisentong was 0.15 mg?kg^?1 in tobacco and 0.03 mg kg^?1 in soil, and the limit of quantification (LOQ) was 0.5 mg kg^?1 in tobacco and 0.1 mg kg^?1 in soil, respectively. For field experiments, the half-lives of saisentong in tobacco from Guizhou and Hunan were 5.9 and 1.6 days, respectively; those in soil were 14.7 and 12.0 days, respectively. The results suggest that the saisentong dissipation curves followed the first-order kinetic. The terminal residues of saisengtong in tobacco ranged from 0.5 to 9.39 mg kg^?1 at pre-harvest intervals (PHI) of 7, 14 and 21 days.     

Analysis of triallate residue and degradation rate in wheat and soil by liquid chromatography coupled to tandem mass spectroscopy detection with multi-walled carbon nanotubes

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the analysis of triallate residue in wheat and soil was developed and validated. Multi-walled carbon nanotubes were used as clean-up sorbent. The residual levels and dissipation rates of triallate in wheat and soil were determined by liquid chromatography–tandem mass spectrometry. The limit of quantification was established as 0.01, 0.02 and 0.05 mg kg^?1 for soil, wheat and wheat plant samples, respectively. The average recoveries of triallate ranged from 77% to 108% at fortified levels of 0.01–0.5 mg kg^?1 with relative standard deviations of 3.0–8.4% (n = 5). From residue trials at three geographical experimental plots in China, the results showed that the half-lives of triallate in soils were 1.13–1.63 days. For trials applied according to the label recommendation, the final residues of triallate in wheat at harvest time were all below 0.05 mg kg^?1 (the maximum residue levels of China, Japan, Korea and the US).     

Transfer of Metals from Soil to Crops in an Area near a Coal Gangue Pile in the Guqiao Coal Mine,China

A field survey was conducted to investigate the metal contamination in coal gangue, soils, and crops (rice and soybeans), and to evaluate the possible health risks to the local population through food chain transfer near a coal gangue pile in the Guqiao Coal Mine, China. Contamination levels of zinc, lead, cadmium, and copper in coal gangue, soils, and crops were measured, and bio-accumulation factors from soil to crops were determined; the health risks were calculated accordingly. Results showed that both coal gangue and soil contained high levels of cadmium (0.15 mg kg^?1and 0.20 mg kg^?1) exceeding the background value of the soil. The lead soil concentration was low (9.99 mg kg^?1), but lead in rice (0.38 mg kg^?1) exceeded the maximal permissible limit of 0.2 mg kg^?1. For some tissues of crops studied, there was a significant correlation between the bio-accumulation factor values and the corresponding soil metal concentrations that were best described by a power equation. Oral intake of zinc, cadmium, and copper through crops posed no health risk to local residents, although hazard indices for rice (0.87–2.88) and soybeans (0.06–0.09) suggested that ingestion of rice grains was unsafe for human health. Therefore, rice was inappropriate to be planted in the soil surrounding this coal mine.     

Persistence and dissipation of fluopicolide and propamocarb on cabbage and soil under semi-arid climatic conditions

Persistence and dissipation of fluopicolide and propamocarb were studied on cabbage and soil as per good agricultural practices over a period of 2 years. A modified QuEChERS analytical method in conjunction with gas chromatography (GC) and GC–mass spectrometry was used for analysis of fluopicolide and its metabolite, 2,6-dichlorobenzamide, and propamocarb in cabbage and soil. The results of the method validation were satisfactory with recoveries within 74.5–100.81% and relative standard deviations 4.8–13.9% (n = 6). The limit of detection (LOD) and limit of quantification (LOQ) of both fluopicolide and 2,6-dichlorobenzamide were 0.003 µg mL^?1 and 0.01 mg kg^?1, respectively. The LOD and LOQ of propamocarb were 0.03 µg mL^?1 and 0.1 mg kg^?1, respectively. During 2013, the initial residue deposits of fluopicolide on cabbage were 0.60 and 1.48 mg kg^?1 from treatments at the standard and double doses of 100 and 200 g a.i. ha^?1 which dissipated with the half-life of 3.4 and 3.7 days. During 2014, the residues were 0.49 and 1.13 mg kg^?1 which dissipated with the half-life of 4.2 and 5.1 days. Propamocarb residues on cabbage were 5.36 and 12.58 mg kg^?1 in the first study (2013) and 4.85 and 10.26 mg kg^?1 in the second study (2014) from treatments at the standard and double doses of 1000 and 2000 g a.i. ha^?1, respectively. The residues dissipated with the half-life of 4–5.5 days. The preharvest interval, the time required for fluopicolide + propamocarb residues to dissipate below the maximum residue limits (notified by EU) at the standard dose, was 11.8 and 14 days during 2013 and 2014. Residue of 2,6-dichlorobenzamide was always <LOQ in cabbage. Residues of fluopicolide, 2,6-dichlorobenzamide and propamocarb were <LOQ in field soil at harvest.     

Analysis of residue dynamics of clofentezine in tangerine and field soil by QuEChERS and HPLC-UV methods

A field experiment was conducted to evaluate clofentezine residue levels and dissipation trend in tangerine and soil for the safe application of clofentezine. A modified QuEChERS-HPLC-UVD method was developed to analyse clofentezine in tangerine and soil. Tangerine samples were homogenised and extracted by acetonitrile and then cleaned up with dispersive solid phase extraction (dSPE) by primary and secondary amine (PSA) and C₁₈. Clofentezine residue was determined by high-performance liquid chromatography (HPLC) with a UV detector (UVD) at the wavelength of 268 nm. The presented method achieved the good linear relationship within the range from 0.05 to 5.0 mg kg^?1 for clofentezine (R² > 0.998). At the fortification levels of 0.05, 0.50 and 1.00 mg kg^?1 in tangerine pulp, tangerine peel and soil, recoveries ranged from 75.9% to 117.7% with relative standard deviations (RSD) less than 8.2%. In the supervised field trials, the half-lives of clofentezine in tangerine and soil were approximately 11.3 and 8.6 days, respectively. At pre-harvest interval of 21 days, the residue of clofentezine in tangerine was below the maximum residue limits (MRL) (0.5 mg kg^?1). Clofentezine (Water Dispersible Granule, 80%) was recommended to be sprayed twice and the recommended dosage ranged from 250 to 375 mg kg^?1.     

Residues and risk assessment of bifenthrin and chlorfenapyr in eggplant and soil under open ecosystem conditions

Dissipation and residue levels of bifenthrin and chlorfenapyr in eggplant and soil under field conditions were investigated using gas chromatography coupled with an electron capture detector (GC-ECD). The mean recoveries of bifenthrin and chlorfenapyr were 85.2–104.9%, with relative standard deviations (RSDs) of 0.5–9.1%. The limit of quantification (LOQ) was 0.01 mg kg^?1. Bifenthrin exhibited half-lives of 3.3 to 4.1 days in eggplant and 17.8 to 25.7 days in soil; the half-lives of chlorfenapyr were 3.5 to 3.8 days in eggplant and 21.7 to 27.7 days in soil. During harvest, the terminal residues of bifenthrin and chlorfenapyr were below 0.031 and 0.083 mg kg^?1, respectively. Risk assessment for different groups of people in China was evaluated. The risk quotients (RQs) of bifenthrin and chlorfenapyr were ranged from 0.0068 to 0.0148 and from 0.0033 to 0.0072, respectively. These results may provide guidance on reasonable use of pesticides and serve as a basis for establishing maximum residue limits (MRLs) in China.     

Application of INAA for phyto-accumulation study of selenium by chickpea plant

The phyto-accumulation efficacy of selenium (Se) from soil by chickpea plant is reported. Chickpea plants were grown in soil having different concentrations (1–4 mg kg^?1) of Se. Samples of soil and different parts of chickpea plants in Se rich soil were analyzed for determination of Se concentrations by instrumental neutron activation analysis (INAA). Samples were irradiated in self-serve facility of CIRUS reactor, BARC, Mumbai at a neutron flux of the order of 10¹³ cm^?2 s^?1. The gamma activity at 264.7 keV of ⁷⁵Se (119.8 d) was measured using a 45% relative efficiency HPGe detector coupled to MCA. Dependence of Se distribution in soil and plants on its spiking concentration was evaluated in this work. The Se concentrations determined in plant parts grown in control soil and in soil spiked with Se (4 mg kg^?1) are in the range of 0.6–0.8 and 65–68 mg kg^?1 respectively.     

Residue dynamics of chlorpyrifos and cypermethrin in/on pomegranate (Punica granatum L.) fruits and soil

Study on the residue dynamics of chlorpyrifos and cypermethrin in/on pomegranate (Punica granatum L.) and soil was carried out by conducting supervised field trials as per good agricultural practices. A modified QuEChERS was used to extract the insecticides in pomegranate peel and aril and soil. The limit of quantification (LOQ) of chlorpyrifos and cypermethrin were 0.01 and 0.05 mg kg^?1, respectively. Residues of the insecticides remained on the fruit surface and movement to the edible part (aril) was not observed. The residues after treatment on fruit peel were 2.46 and 3.51 mg kg^?1 and 2.84 and 4.54 mg kg^?1 for chlorpyrifos and cypermethrin, respectively, from recommended and double dose treatments. Chlorpyrifos residues degraded faster compared to cypermethrin. The pre-harvest intervals (PHIs) of chlorpyrifos were 22 and 35 days and those of cypermethrin 50 and 73 days, respectively, at recommended and double dose treatments. In the experimental field soil after the second application chlorpyrifos residues were 0.21 and 0.46 mg kg^?1 and cypermethrin residues 0.15 and 0.36 mg kg^?1. At harvest, both pesticides showed residues below the LOQ. Based on this study, application of cypermethrin towards harvest may be avoided whereas chlorpyrifos can be applied with 22 days PHI.     

Simultaneous Analysis of Hexaconazole, Myclobutanil, and Tebuconazole Residues in Apples and Soil by SPE Clean-Up and GC with Nitrogen–Phosphorus Detection

A facile and sensitive method utilizing capillary gas chromatography with nitrogen phosphorus detection (GC–NPD) has been developed and validated for simultaneous analysis of hexaconazole, myclobutanil, and tebuconazole, three broad-spectrum systemic fungicides, in apples and soil. Two samples were fortified with the three pesticides and subjected to ultrasonic extraction, followed by solid-phase extraction (SPE) to remove coextractives, before analysis by GC–NPD. SPE procedures were performed on PSA cartridges (500 mg, 3 mL), the analytes being eluted with n-hexane–acetone (9:1 v/v, 2 mL). Recovery of three pesticides from the fortified apple and soil samples ranged from 94.5 to 107.3% with relative standard deviations less than 9.7% at the three spike levels (0.01, 0.1, and 0.5 mg kg^?1). Limits of quantification of the method for apple and soil were 0.01 mg kg^?1, sufficiently below the maximum residue limits. Direct confirmation of the analytes in samples was achieved by gas chromatography–mass spectrometry (GC–MS).     

MSPD–GC–MS–MS Determination of Residues of 15 Organic Nitrogen-Containing Pesticides in Vegetables

A novel and simple method for determination of 15 organic nitrogen-containing pesticides in vegetables using matrix solid-phase dispersion (MSPD) coupled with gas chromatography tandem mass spectrometry (GC–MS–MS) has been developed. The efficiencies of different sorbents (florisil, silicone, neutral alumina) for the MSPD were compared. Mean recoveries of the method using neutral alumina varied from 73.26 to 111.83% with relative standard deviations of 0.79–15.33% in the concentration range of 0.01, 0.02 and 0.05 mg kg^?1. The limits of detection were typically in the 0.0007–0.0320 mg kg^?1 range, which were 10–100 times lower than the maximum residue levels established by the European Union. This method was applied to residue detection in vegetables, in which organic nitrogen-containing compounds were detected at low concentrations.     

Persistence of trifloxystrobin and tebuconazole in banana tissues and soil under the semi-arid climatic conditions of Karnataka,India

Trifloxystrobin and tebuconazole are used for control of Sigatoka leaf spot disease of banana. This study was conducted to evaluate residue persistence of the fungicides in/on banana fruit, other edible parts and soil after spray application of the combination formulation, Nativo 75 WG, at the standard dose, 87.5 + 175 and double dose, 175 + 350 g a.i. ha^?1. The fungicides were extracted from banana and soil with acetone, partitioned into dichloromethane and cleaned-up using activated charcoal for trifloxystrobin and primary/secondary amine (PSA) for tebuconazole samples. The limit of quantification of the method was 0.05 mg kg^?1 for both fungicides. Initial residues of trifloxystrobin were 0.444 and 0.552 mg kg^?1 in/on banana with peel (whole fruit), which reached <0.05 and 0.065 mg kg^?1 after 30 days from treatment at the standard and double doses, respectively. Tebuconazole residues were 0.636 and 960 mg kg^?1 initially and reduced to 0.066 and 0.101 mg kg^?1 after 30 days. Trifloxystrobin and tebuconazole degraded with the half-life of about 11 days. Trifloxystrobin or its metabolite was not detected in the fruit pulp. Tebuconazole being systemic in nature moved to the fruit pulp which was highest on the 3rd day (0.103 and 0.147 mg kg^?1) and remained for 15 days. Matured banana fruit, flower, pseudostem and field soil were free from fungicide residues. For consumption of raw banana 43 days pre-harvest interval (PHI) is required after treatment of the combination formulation. Therefore application of the fungicides towards maturity stage of the fruits may be avoided.     

Fate of hexaconazole and isoprothiolane in rice,soil and water under field conditions

Residue dissipation of hexaconazole and isoprothiolane in the rice field ecosystem was determined by gas chromatography coupled with electron capture detector. Hexaconazole and isoprothiolane (33% microemulsion) were applied at two dosages, 396 g a.i. ha^–1 (the recommended dosage) and 594 g a.i. ha^–1 (1.5 times the recommended dosage) in the experimental fields in Guizhou, Hunan and Heilongjiang provinces, China, during 2011–2012. The limits of detection and limits of quantification in brown rice were 0.006 and 0.02 mg kg^–1 for hexaconazole, 0.0072 and 0.024 mg kg^–1 for isoprothiolane, respectively, and they were much below the maximum residue limits (MRLs, 0.1 mg kg^–1 for hexaconazole and 1.0 mg kg^–1 for isoprothiolane) set by China. Average recoveries of hexaconazole in water, soil, rice plants and brown rice ranged from 77.3% to 93.8% and for isoprothiolane ranged from 78.1% to 99.9% with relative standard deviations < 10%. The results showed that during harvest, the terminal residue levels of hexaconazole and isoprothiolane in brown rice samples were well below the MRLs of China following the interval of 7 days after last application. Therefore, a dosage of 396 g a.i. ha^–1 was recommended, which could be considered as safe to human beings.     

Applications of EDXRF and INAA techniques for studying impact of industries to the environment

In this study we present quantitative elemental analysis techniques like energy dispersive X-ray fluorescence analysis and instrumental neutron activation analysis to assess the impact of industrial discharge on environment. Two cases are discussed, i.e., (a) enrichment of zinc levels in the soil (1080 ± 76 mg kg^?1) and zinc uptake ranging between 628 and 40 mg kg^?1 in edible plants and cereals grown in agricultural fields near an active zinc smelter, Rajasthan; (b) depth-wise distribution of Cr, Pb and other metals in the sediment core samples from Sundarban wetland, West Bengal, indicating waste discharge from tanneries and other industries.     

Determination of concentrations of chromium and other elements in soil and plant samples from leather tanning area by Instrumental Neutron Activation Analysis

Chromium, one of the toxic elements, along with other elements has been determined in samples of soil and plant (leaves and seeds) from Jajmau Area, Kanpur district, India, which is irrigated with effluent waste water from leather tanning industries. Soil and plant samples were collected from these areas and analyzed by Instrumental Neutron Activation Analysis (INAA) using high flux reactor neutrons and high resolution gamma-ray spectrometry. Concentrations of fifteen elements in soil and five elements in plant samples were determined by relative method. Chromium concentrations were found to be in range of 45–3,900 mg kg^?1in soil samples and 14–83 mg kg^?1 in plant samples. This study showed that Cr is present in significant amounts, in the soil as well as in the plant samples, near to the leather tanning area. As a part of quality control work, IAEA reference material (RM) SL-3 and NIST standard reference material (SRM) 1645 were analyzed and the quality of the results has been evaluated by calculating % deviations from recommended/literature/certified values.     

Residues and dissipation of guadipyr in rice ecological system

A modified QuEChERs method with liquid chromatography-tandem mass spectrometry for analysis of guadipyr residue and dissipation in rice matrices, paddy soil and paddy water was developed and validated. Mean recoveries and relative standard deviations in paddy soil, paddy water, rice plant, rice straw, rice hull and husked rice matrices at three spiking levels were 83.1–116.5% and 1.6–9.5%, respectively. The half-life of guadipyr was determined in 2 years at three different field sites in China via a dissipation experiment. The half-lives of guadipyr in paddy water were 0.22–0.37 days, 0.24–3.33 days in paddy soil and 0.44–1.90 days in rice plant. The terminal residues of guadipyr ranged from ND (concentrations of guadipyr were below limit of detection) to 50 μg kg^?1 in paddy soil, 10–470 μg kg^?1 in rice hull, ND70 μg kg^?1 in husked rice and ND to 110 μg kg^?1 in rice straw. The results would be helpful in fixing maximum residue limit of guadipyr, a new insecticide, in rice.     

Uncertainty Analysis of Chlormequat Residue in Fruits by LC�CMS�CMS

A method for determination of chlormequat (CCC) residue in fruits by liquid chromatography?Ctandem mass spectrometry (LC?CMS?CMS) was developed. Residue of CCC was extracted from samples with methanol?Cwater (v/v, 1:1) containing 1.0% acetic acid, cleaned up by strong cationic exchange (SCX) cartridge, and then determined by LC?CMS?CMS. The method showed good linearity over the concentration range 0.002?C5.0 mg kg^?1 with correlation coefficient above 0.997. The limit of detection (LOD) and limit of quantitation (LOQ) for CCC were 5 × 10^?4 mg kg^?1 (S/N = 3) and 0.002 mg kg^?1 (S/N = 10), respectively. Recoveries for CCC at three spiked levels (0.025, 0.050, and 0.20 mg kg^?1) were in the range 80?C102%. Estimation of measurement uncertainty was calculated for CCC at the level of 0.025 mg kg^?1 in fruits. The results demonstrated that the uncertainty of recovery was the main contribution to the combined standard uncertainty. The relative combined standard uncertainties associated with the method ranged from 11 to 13%, depending on the sample matrices.     

Analysis of bioaccessible concentration of trace elements in plant based edible materials by INAA and ICPMS methods

The total metal concentration and bioaccessible concentration of Cr, Mn, Fe, Cu, Zn, Se in Momordica charantia, Asparagus racemosus, Terminalia arjuna and Syzyzium cumini were measured by instrumental neutron activation analysis and by inductively coupled plasma mass spectrometry analysis (ICP-MS). The bioaccessible concentrations were determined in the gastrointestinal digest obtained after treating dried powdered samples sequentially in gastric and intestinal fluid of porcine origin at physiological conditions. The bioaccessible concentration of Fe was in the range of 58–67 mg kg^?1, Mn was 10.2–14.6 mg kg^?1, Cu was 3.7–4.8 mg kg^?1 and Zn was 10.6–18.4 mg kg^?1, were within the safety limits set for vegetable food stuff set by Joint FAO/WHO. The bioaccessibility of Zn, an essential element, was high (40–50 %) in M. charantia and in S. cumini. In addition, the total metal contents and bioaccessible concentration of Ni, Se, Cd and Pb in these samples were measured by ICP-MS. The total Cd content in S. cumini (2.6 ± 0.2 mg kg^?1) and its bioaccessible concentration (0.6 mg kg^?1) were strikingly high as compared to the other samples. Though total Hg contents were determined by ICP-MS, but their bioaccessible concentrations were below the detection limit (0.036 mg kg^?1).     

Biodegradation of imidacloprid in sandy loam soil by Bacillus aerophilus

A study of the biodegradation of imidacloprid in soil was carried out under laboratory conditions. Sandy soil samples were fortified with imidacloprid at 50, 100 and 150 mg kg^?1 along with 45 x 10⁷ colony forming units (cfus) of Bacillus aerophilus and the samples were compared with unamended soil. The samples were extracted with acetonitrile, cleaned up by treatment with primary secondary amine sorbent and graphitised carbon black. The residues of imidacloprid and its metabolites were analysed by high performance liquid chromatography. The parent compound, imidacloprid, was found to be more persistent in both the treatments. Among metabolites, the highest values were obtained for urea and olefin while 5-hydroxy, 6-chloronicotinic acid (6-CNA), nitrosimine and nitroguanidine (NTG) were also observed in all the treatments in amended soil. In case of unamended (control) soil, 6-CNA was found to be the most persistent metabolite followed by olefin, urea, 5-hydroxy, nitrosimine and NTG metabolites. Total imidacloprid residues for control soil samples followed first-order kinetics at 50 and 150 mg kg^?1 but in case of control imidacloprid fortified at 100 mg kg^?1, the total residues of imidacloprid and its metabolites followed pseudo-first-order kinetics. The respective half-life value for 50 mg kg^?1 was 25.08 days and 30.10 days for both 100 and 150 mg kg^?1. However, total imidacloprid residues followed pseudo-first-order kinetics for its applications at 50, 100 and 150 mg kg^?1 in sandy loam soil amended with B. aerophilus. The half-life values for 50, 100 and 150 mg kg^?1 were worked out to be 14.33, 15.05 and 18.81 days, respectively. With the use of B. aerophilus, the reduction percentage of initial applied dose imidacloprid in sandy loam soil was found to be higher in all the three doses as compared to that of the control samples.