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The photodegradations of three selected neonicotinoid insecticides nitenpyram, thiacloprid, and acetamiprid were investigated in both water and soil samples under natural sunlight, UVA light, and UVB light. The results indicate that these insecticides undergo significant degradations when subjected to sunlight, whether they are in deionized (DI) water, tap water, and DI water containing 100 mg/L humic acids or in soil. The degradation half-lives of nitenpyram, thiacloprid, and acetamiprid in tap water under sunlight were found to be 3.7, 4.7, and 8.9 h, respectively, in DI water 5.4, 6.3, 9.1 h, respectively, in DI water containing 100 mg/L humic acids 3.6, 3.3, 6.5 h, respectively, and in soil 7.5, 7.9, and 15.9 h, respectively. The degradation due to hydrolysis was found insignificant as compared to photodegradation. The examination of the effects of light source revealed that the UVB in the sunlight plays a major role in the photodegradation of these three neonicotinoids, and the effects of UVA and visible light are negligible. The analysis on the degradation products indicated that the nitroguanidine group in these insecticides is unstable and prone to break up under sunlight. A total of nine degradation products were detected, of which the health effects and the fate and transport in the environment need to be further studied., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A method for simultaneous quantitation of rimsulfuron, quizalofop-P-ethyl and quizalofop-P in potato plant, soil and potato tuber samples was established. The mean recoveries of rimsulfuron, quizalofop-P-ethyl and quizalofop-P in different matrices spiked with them were 81.4%-101.1%, 76.1%-99.0% and 77.4%-106.4% with relative standard deviations (RSDs) of 2.7%-13.3%, 0.9%-5.5%, 1.7%-11.3%, respectively. The open-field trials in China were conducted in potato cultivation system of Changchun and Jinan. The results indicated that the half-lives of rimsulfuron and quizalofop-P-ethyl were 0.04-13.1 days. The residues of quizalofop-P during the harvest time in Jinan soil were < 0.01-0.044 mg kg -1 , while there was no residue of target herbicides detected in all other samples. The risk assessment results demonstrated that the risk quotients (RQs) of rimsulfuron and quizalofop-P-ethyl were 7.857 × 10 -5 and 8.730 × 10 -3 , respectively, which exhibited an acceptable dietary risk to Chinese consumers.

The effect of vermicompost added to a loam soil on the leaching behaviour of two herbicides (triclopyr and fluroxypyr) was examined. Mobility of the herbicides was assessed using disturbed soil columns under laboratory conditions. In both cases, the addition of vermicompost significantly increased the sorption of the compounds. For both, DT 50 values were slightly higher in the amended soil, due to the increased adsorption. Rate constants (k) calculated according to pseudo-first order model were significantly lower in the case of triclopyr (very persistent), which led to a much lower degradation rate compared to fluroxypyr (persistent) in both unamended and amended soils. Values calculated for the experimental leaching index (ELI) in unamended and amended soils showed medium and high leachability for fluroxypyr (0.31 and 0.29) and triclopyr (0.72 and 0.70), respectively. Other index-based screening models (GUS, RLPI, LIX) also catalogue both herbicides as potential leachers. Results confirm that triclopyr and fluroxypyr may contaminate groundwater resources.

Tetraniliprole (TTP) is a new bisimide-based insecticide. Three typical surface soil samples were collected in farmland across China, including Jiangxi red soil (RS), Shandong yellow brown soil (YBS), and Heilongjiang black soil (BS). Adsorption, desorption and leaching experiments were conducted by using equilibrium oscillation and soil column leaching methods at 25°C ± 1°C. The isothermal adsorption and desorption curves of TTP in the above three soils were in accordance with the Freundlich model. The adsorption/desorption constants (K ads-f /K des-f ) were 41.96-64.48 and 3.62-43.65, respectively. There is a certain hysteresis in the desorption curve, and the hysteresis coefficient (H) was between 0.14 and 0.89. Besides, the leaching properties of TTP in three soils were different. The leaching of TTP in RS and YBS was easy, while difficult for BS. It is concluded that the different adsorption-desorption ability and leaching ability of TTP in the above three soils was attributed to the distinct contents of organic matter (OM) and cation exchange capacity (CEC) in soil.

Using clodinafop propargyl (CF) as a sole carbon, nitrogen and energy source, a CF-degrading bacterial strain was isolated from crop soil field. This strain was identified as Pseudomonas sp. strain B2 by 16S rRNA gene sequence analysis. 87.14 % CF was degraded out of initial provided 80 mg/L CF. Degradation of CF was accompanied by release of chloride ion. The optimal pH and temperature for the growth of B2 were 7.0 and 30°C, respectively in the mineral salts medium supplemented with CF. An actively growing culture of strain B2 degraded CF to clodinafop acid and 4-(4-Chloro-2-fluoro-phenoxy)-phenol within 9 h, as determined by GC–MS analysis. A metabolic pathway for the degradation of CF by B2 has been proposed

Field trials were carried out in three provinces of China to study the dissipation and residue of forchlorfenuron in citrus fruits. The results had shown that the degradation rate of forchlorfenuron in citrus fruits followed the first-order kinetics equation C = A∙eBt. The half-lives of forchlorfenuron were 15.8-23.0 days, the final residues of forchlorfenuron in pulp were all ≤0.002 mg/kg, and most of the residues were concentrated in the peel. The risk assessment revealed that no significant potential health risk would be induced by forchlorfenuron in citrus fruits. Therefore, it could be safe to apply forchlorfenuron in citrus fruits, and the results of this study could also be regarded as a reference to the setting of maximum residue limit for forchlorfenuron in citrus fruits in China.

Thiacloprid is a systemic neonicotinoid. The study hypothesized that difference may be seen in the rate of dissipation of thiacloprid when applied on non-transgenic and transgenic cabbage. Thiacloprid was estimated by HPLC. Half life of thiacloprid in transgenic as well as in normal cabbage ranged between 12.3-13.1 days in two doses of application. Under field condition, after 15 days, 59.2% and 54.3% dissipation was recorded at lower and higher rates of application in transgenic cabbage, where as the insecticide dissipated 57.5% and 59.1% for single dose and double dose application, respectively in non-transgenic cabbage. The study establishes that there is no significant difference in dissipation of a systemic pesticide in transgenic versus non-transgenic cabbage. Decontamination of thiacloprid contaminated cabbage was carried out by different chemical treatments. The application of 0.5% NaHCO(3) (an edible alkali) may be recommended for decontamination. Thiacloprid residues in the day-3 field samples of cabbage could be reduced below Japanese MRL (1.0 mg kg(-1)) by treating with 0.5% NaHCO(3) solution for 1 h.

Thiacloprid residues were estimated in green tea leaves, processed tea and tea infusion by HPLC-Diode Array detection. The average initial deposits of thiacloprid (Alanto 240 SC) on the green tea leaves were found to be 3.72 and 6.77 μg g(-1) at single and double doses, respectively. The results showed that thiacloprid dissipated faster in green tea leaves following a first order reaction kinetics at both application rates. The amount of dissipation in 14 days was 93.37% and 91.62% for single and double doses respectively. Half life (T(1/2)) for degradation of thiacloprid in green tea leaves were observed to be 3.34 and 3.58 days at single and double doses respectively. Thiacloprid residues in processed tea ranged from 0.16 to 0.63 μg g(-1) on seventh day and no residues could be detected on 14th day at single dose. Infusion study indicated that thiacloprid did not infuse into tea liquor from processed tea. The limit of determination was found to be 0.05 μg g(-1).

In order to examine the persistence behavior, safety evaluation and utilization of residue data for fixation of thiacloprid MRL, a supervised field trial in tea was conducted at Darjeeling. The HPLC analysis of thiacloprid in green tea leaves indicates that the initial deposits of 2.14 and 3.95 mg kg(-1), which declined gradually and persisted until day 14 to the tune of 0.23 and 0.45 mg kg(-1) respectively. The residues in processed tea samples prepared from green tea leaves of 7 and 14th day were 3.0-3.8 times less. Thiacloprid did not infuse to tea liquor from processed tea. The half-life value in green tea leaves ranged from 4.29 to 4.31 days. Considering the EU MRL value of 10 mg kg(-1) and risk assessment calculation, thiacloprid at 30 g a.i. ha(-1) appears to be safe in plant protection schedules and first round of plucking of green tea leaves on day 7 is recommended.

Residue dynamics of acetamiprid in watermelon and soil was studied in this paper utilizing liquid chromatography with tandem mass spectrometry (LC-MS/MS). The LODs for acetamiprid in whole watermelon, melon flesh and soil were 0.002 mg/kg. The fortified recoveries ranged from 73.7% to 107.5% with relative standard deviations (RSDs) of 1.7%-5.9%. Acetamiprid dissipated in watermelon and soil with the half-life 3.12-3.92 days and 1.18-1.46 days in two locations Beijing and Shandong provinces, respectively. In the terminal residue experiment, no higher residue than 0.01 mg/kg in melon flesh and 0.3 mg/kg in whole watermelon and soil were detected.

Residue dynamics of thiacloprid in cabbage and soil was studied in this paper utilizing liquid chromatography with tandem mass spectrometry (LC-MS/MS). The field trial was conducted in two sites: Beijing, China and Hubei, China. Thiacloprid dissipated rapidly with the half-life 1.3-1.6 days in cabbage and 2.1-3.1 days in soil. In the terminal residue experiment, no higher residue than 0.06 mg/kg in cabbage and 0.16 mg/kg in soil was detected, which was far below either EU MRL (0.2 mg/kg) or Japan MRL (1 mg/kg)., (© Springer Science+Business Media, LLC 2011)

A simple and reliable analytical method for analysis of fluroxypyr-meptyl residue in rice, soil and water was investigated. The residue levels and dissipation rates of fluroxypyr-meptyl (34% AS) were determined by GC-MSD in selected ion monitoring mode. In the supervised field trials, the half-life of fluroxypyr- meptyl in rice plant was in the range 1.25-4.13 days. The half-lives of fluroxypyr-meptyl in soil and water were 2.29 and 1.73 days, respectively. In order to assess the dissipation of fluroxypyr-meptyl in the environment, a laboratory simulated experiment was carried out in soil and water. The terminal residues of fluroxypyr-meptyl in rice plant, husked rice, rice hull and soil samples were undetectable at harvest. It showed that fluroxypyr-meptyl may be safe to use according to the recommended dosage suggested by the corporation.

Chlorfluazuron residues were determined in the peaches that were sprayed at dosage (a.i. 0.0167 kg 10a(-1)), using an analytical method that was validated as follows; r (2) = 0.9999, 0.02 mg kg(-1) (LOQ) and 87.8-93.6% (recovery). The residues from all samples were lower than the MRL (0.5 mg kg(-1), Korea). A maximum 0.27 mg kg(-1) of chlorfluazuron was detected in the samples applied at 6 days before harvest. The results signify that the 10% SC product would be used safely as an insecticide if it is applied two or three times onto peaches, with applications given until 6 days prior to harvest.

A simple, sensitive method for the analysis of nicosulfuron in corn and soil was developed. Samples were extracted with acetonitrile: water (2:3, V/V) mixture and partitioned with dichloromethane. After concentration, the soil sample extracts were detected using high performance liquid chromatography-ultraviolet detector (HPLC-UVD), and the corn sample extracts were detected using high performance liquid chromatography-mass spectrometry detector (HPLC-MSD). The fortified recoveries at 0.05-1.0 mg/kg were 79.7%-115.8%, with the relative standard deviation of 1.40%-13.8%. The limit of detection of the analytical method was 0.05 ng at a signal-to-noise ratio of 3, and the limit of quantification was 0.05 mg/kg for both corn and soil. The dissipation dynamics of nicosulfuron in the field trials in Beijing and Changchun were investigated. The half-lives of nicosulfuron in corn plants were 0.73 days in Beijing and 0.53 days in Changchun, both with a dissipation rate of 90% over 7 days after application. The half-lives in soil were 13.64 days both in Beijing and in Changchun with a dissipation rate of 90% over 21 days. Low residues and short half-life in corn suggested that nicosulfuron could be safely used in corn crops with the suitable dosage and application.

Honey bee (Apis mellifera carnica) colonies were placed in two apple orchards treated with the insecticides diazinon and thiacloprid and the fungicide difenoconazole in accordance with a Protection Treatment Plan in the spring of 2007. Pollen and bee bread were collected from combs inside the hives. The residue of diazinon in pollen loads 10 days after orchard treatment was 0.09 mg/kg, and the same amount of residue was found in bee bread 16 days after treatment. In pollen loads 6 days after application 0.03 mg/kg of thiacloprid residues and 0.01 mg/kg of difenoconazole were found on the first day after application. Possible sub-lethal effects on individual honey bees and brood are discussed.

An experiment was conducted to find out the persistence of two different formulations of Acetamiprid, namely 20% SP (soluble powder) and 20% SL (soluble liquid) in chili. Following three applications @ 20 g a.i./ha and 40 g a.i./ha, the initial deposits were found to be 0.0207, 0.0405, 0.0244 and 0.1039 microg/g. The half-life values of acetamiprid in chili were in the range of 2.24-4.84 days. A waiting period of 1 day is suggested.