Determination of quizalofop-p-ethyl in onion: residual dissipation pattern, weed control efficiency, and food safety assessment under field conditions.

Monitoring pesticide residue levels becomes crucial to maintain quality and guarantee food safety as the consumption of onion green leaves and immature and mature bulbs (either raw or processed) rises. A field experiment was conducted for two consecutive seasons with quizalofop-p-ethyl (5% EC) at 50 and 100 g a.i. ha-1 to evaluate weed control efficiency and to determine terminal residues. Post-emergence application of fop herbicide at 100 g a.i. ha-1 kept the weed density and dry weight reasonably at a lower level and enhanced the productivity of onion with higher economic returns. A rapid, sensitive, and analytical method was developed using high-performance liquid chromatography (HPLC) with excellent linearity (r2 > 0.99). The limit of quantification for quizalofop-p-ethyl was established at 0.04 mg kg-1 with signal to noise (S/N) ratio ≥ 10. The method was successfully applied and initial quantified residues were in the range of 2.5-4.4 mg kg-1 irrespective of seasons and doses. Finally, the presence of targeted herbicide residues in harvested samples was confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS) under optimized operating conditions. Dietary risk assessment assured harvested onions were safe for consumption at the recommended dose. It also can be concluded that quizalofop ethyl did not adversely influence soil micro-organisms at standard rates of application.

Persistence, dissipation, and risk assessment of a combination formulation of trifloxystrobin and tebuconazole fungicides in/on tomato.

Multi-locational supervised field trials were conducted in different agro-climatic regions in India to study dissipation of trifloxystrobin and tebuconazole in tomato after spraying a combination formulation (trifloxystrobin 25% + tebuconazole 50%, 75WG) at recommended doses: (i) single (trifloxystrobin 87.5 g a.i. ha-1 + tebuconazole 175 g a.i. ha-1) and (ii) double (trifloxystrobin 175 g a.i. ha-1 + tebuconazole 350 g a.i. ha-1). Fruit samples were extracted with ethyl acetate using a modified QuEChERS method. The residues (parent fungicides + metabolite) were analyzed and confirmed by GC-ECD and GC-MS, respectively. The half-life (t1/2) of trifloxystrobin and tebuconazole in tomato varied from 1.08 to 1.72 and 1.13 -to 1.64 days at single; and 1.27 to 2.13 and 1.24 to 1.96 days at double dose, respectively. Since maximum residue limit (MRL) at pre-harvest interval (PHI) of 5 days is impractical, as tomato is usually harvested and consumed almost everyday after the last spray, the risk assessment was performed at minimum PHI of 1 day. Accordingly, on the basis of supervised field trial data and using OECD MRL calculator, MRL of 0.5 and 1.5 mg kg-1 at single dose were proposed for trifloxystrobin and tebuconazole in/on tomato, respectively.

Multilocation field trials for risk assessment of a combination fungicide Fluopicolide + Propamocarb in tomato.

Dissipation kinetics of two systemic fungicides, namely fluopicolide and propamocarb used as a combination formulation (Infinito 68.75 SC), were studied on tomato at four different locations by the All India Network Project on Pesticide Residues to recommend their pre-harvest interval (PHI) and to propose the maximum residue limits (MRL) for the two fungicides based on chronic hazard exposure assessment. The combination fungicide was sprayed thrice at the recommended dosage of 93.75 g a.i./ha fluopicolide and 937.50 g a.i./ha propamocarb as well as at double the recommended dosage of 187.50 g a.i./ha fluopicolide and 1875.0 g a.i./ha propamocarb on tomato crops and the residues were monitored periodically by GC-MS. The fungicides dissipated to below the limit of quantification (LOQ) within 10 to 15 days, with a half-life of 2-4 days for fluopicolide and 1-2 days for propamocarb. Taking into consideration the MRLs of codex and calculations made using the method of MRL fixation of the Food Safety and Standard Authority of India (FSSAI) as well as the Organization for Economic Co-operation and Development (OECD) calculator, MRL of 5 mg/kg is proposed for fluopicolide and 15 mg/kg for propamocarb, following critical exposure of the commodity considering PHI of 1 day.

Persistence and risk assessment of spiromesifen on tomato in India: a multilocational study.

Supervised field trials were conducted at four different agro-climatic locations of India to evaluate the dissipation pattern and risk assessment of spiromesifen on tomato. Spiromesifen 240 SC was sprayed on tomato at 150 and 300 g a.i. ha(-1). Samples of tomato fruits were drawn at 0, 1, 3, 5, 7, 10 and 15 days after treatment and soil at 15 days after treatment. Quantification of residues was done on gas chromatograph-mass spectrophotometer in selective ion monitoring mode in the mass range of 271-274 (m/z). The limit of quantification of the method was found to be 0.05 mg kg(-1), while the limit of determination was 0.015 mg kg(-1). Residues were found below the LOQ of 0.05 mg kg(-1) in 10 days at both the doses of application at all the locations. Spiromesifen dissipated with a half-life of 0.93-1.38 days at the recommended rate of application and 1.04-1.34 days at the double the rate of application. Residues of spiromesifen in soil were detectable level (<0.05 mg kg(-1)) after 15 days of treatment. A preharvest interval (PHI) of 1 day has been recommended on tomato on the basis of data generated under All India Network Project on Pesticide Residues. Spiromesifen 240 SC has been registered for its use on tomato by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of spiromesifen on tomato has been fixed by Food Safety Standard Authority of India, Ministry of Health and Family Welfare, Government of India as 0.3 µg/g after its risk assessment.

Dissipation of flubendiamide residues in/on cabbage (Brassica oleracea L.).

Residues of fubendiamide and its metabolite desiodo flubendiamide were estimated in cabbage and soil using high-performance liquid chromatography with UV-vis detector. The initial deposits of flubendiamide residues on cabbage were found to be 0.16 and 0.31 µg g(-1) following two applications of flubendiamide 20 WG at 12.5 (standard dose) and 25 (double dose) g a.i. ha(-1) respectively at 10-days interval. The half-life values (t(1/2)) of flubendiamide on cabbage ranged from 3.4 to 3.6 days. When flubendiamide applied at both the standard and double dose, no detectable residues were found in cabbage and soil at harvest. Thus, a waiting period of 1.63 days was suggested for the safe consumption of flubendiamide-treated cabbage. These data could provide guidance for the proper and safe use of this pesticide on cabbage crops in India.

Assessment of flubendiamide residues in pigeon pea in different agro-climatic zones of India.

Supervised field trials were conducted at the research farms of four agricultural universities located at different agro-climatic zones of India to find out the harvest time residues of flubendiamide and its des-iodo metabolite on pigeon pea (Cajanus cajan) during the year 2006-2007. Two spray applications of flubendiamide 20 WDG at 50 g (T(1)) and 100 g (T(2)) a.i./ha were given to the crop at 15-days interval. The foliage samples at different time intervals were drawn at only one location, however, the harvest time samples of pigeon pea grain, shell, and straw were drawn at all the four locations. The residues were estimated by HPLC coupled with UV-VIS variable detector. No residues of flubendiamide and its des-iodo metabolite were found at harvest of the crop at or above the LOQ level of 0.05 µg/g. On the basis of the data generated, a pre-harvest interval (PHI) of 28 days has been recommended and the flubendiamide 20 WDG has been registered for use on pigeon pea by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India and the MRL has been fixed by Ministry of Health and Family Welfare, Government of India under Prevention of Food and Adulteration as 0.05 µg/g on pigeon pea grains.

Persistence and dissipation of the insecticide flubendiamide and its metabolite desiodo flubendiamide residues in tomato fruit and soil.

A method for residue analysis of flubendiamide and its metabolite desiodo flubendiamide was developed using high performance liquid chromatography. This method was then used to evaluate the residual level and dissipation rate of flubendiamide and desiodo flubendiamide in the tomato fruit. The half-life of flubendiamide in tomato fruit was 1.64 and 1.98 days in recommended and double of the recommended dose, respectively. Tomato fruit and soil samples analyzed on the 10th day after the last spray revealed that flubendiamide and its metabolite desiodo flubendiamide residues at below determination level (0.01 µg g(-1)) at either dose of application.

Degradation dynamics of flubendiamide in different types of soils.

Residual dynamics of flubendiamide in three different types of soils were investigated under laboratory condition. Flubendiamide was applied at 5 and 10 µg g(-1) for each soil and samples drawn periodically were analyzed on HPLC. The results showed that the degradation of flubendiamide in soils were followed first-order kinetics and its average half-lives in three kinds of soils were ranged from 37.62 to 60.21 days. The persistence of flubendiamide in soils significantly increased in the order of coastal soil > red and lateritic soil > new alluvial.

Thiacloprid residues and its safety evaluation in Darjeeling tea.

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.

A comparative study on the persistence of imidacloprid and beta-cyfluthrin in vegetables.

In an effort to compare the persistence of imidacloprid and beta-cyfluthrin, when applied through a ready mix formulation, Solomon 300 OD @ 200 and 400 mL ha(-1) in the fruits of brinjal, tomato and okra, the present study has been made. The study indicated that the dissipation of these insecticides irrespective of fruits followed concentration dependent first order kinetics. The degradation constant and half live value of beta-cyfluthrin varies between -0.287 and -0.642 day(-1) and 1.07 and 2.41 days while that of imidacloprid between -0.21 and -0.34 day(-1) and 1.98 and 3.30 days respectively suggesting that the persistence of beta-cyfluthrin is lower than that of imidacloprid in fruits of these vegetables. Moreover, the persistence of these insecticides when compared between different fruits, it is highest in brinjal followed by tomato and least in okra, a probable clue of which has been proposed based on the non-enzymatic antioxidant content of the fruits.

Persistence and dissipation kinetics of deltamethrin on chili in different agro-climatic zones of India.

Multi-location supervised field trials were conducted at four different agro climatic locations in India to evaluate the dissipation pattern of deltamethrin on chili. Deltamethrin 10 EC was applied on chili @17.5 and 35 g a.i. ha(-1), samples of green chili were drawn at different time intervals and that of red chili and soil at harvest time and quantified by gas liquid chromatography equipped with electron capture detector. The identity of residues were confirmed by Gas Chromatograph-Mass Spectrophotometer in selective ion monitoring mode in mass range 181, 253 m/z. Limit of quantification of the method was found to be 0.01 mg kg(-1). Half-life of deltamethrin at application rate of 17.5 g a.i. ha(-1) varied from 0.36 to 1.99 days and at double the application rate was found to range from 0.38 to 2.06 days. Residues of deltamethrin were found below its determination limit of 0.01 mg kg(-1) in red chili and soil. On the basis of the data generated, Deltamethrin 10 EC has been registered for use on chili in India and its Maximum Residue Limit has been fixed as 0.05 µg/g.

Assessment of the effect of sub-lethal acute toxicity of Emamectin benzoate in Labeo rohita using multiple biomarker approach.

Emamectin benzoate (EMB) is a potent neurotoxin agent, widely used for ectoparasites control in aquaculture, but their detailed toxicological implications in Labeo rohita are unknown. Thus, this study was conceptualized to determine the LC50 and to investigate the effects of two sub-lethal concentrations 1/50th of 96 h LC50 (1.82 µgL-1) and 1/10thof 96 h LC50 (9.1 µgL-1) on hemato-immunological and biochemical responses in L. rohita (mean weight 25.54 ± 2.3 g and length 10.35 ± 2.4 cm) for a period of 24 h, 48 h, and 72 h. LC50 of EMB were 163 µgL-1, 112 µgL-1, 99 µgL-1 and 91 µgL-1 at 24 h, 48 h, 72 h, and 96 h respectively. The safe limit at 96 h LC50 of EMB was 2.30 µgL-1. In EMB treated fish, red blood cells, white blood cells, hemoglobin, and hematocrit counts were reduced (p < 0.05) significantly. Superoxide dismutase (SOD) activity in the liver and kidney declined (p < 0.05) at 72 h while in gill and muscle the activity increased significantly. Glutathione-s-transferase (GST) activity in the liver, gill, and kidney increased (p < 0.05) while muscle decreased significantly. Catalase (CAT) activity in liver, gill, and muscle decreased while in kidney increases. Glutamic-oxaloacetic acid transaminase (GOT) activity and Glutamate pyruvate transaminase (GPT) activity were increased in liver, kidney, and muscle tissue. The change in serum triglycerides, serum protein level was noticed. The level of cortisol, heat shock protein 70 (HSP70), and HSP90 increased (p < 0.05) while the immunological responses like immunoglobulin M (IgM) and complement 3(C3) activity decreased (p < 0.05) in EMB exposed fish. Thus, EMB exposure at two sub-lethal concentrations in L. rohita induces several hemato-immuno, and biochemical alterations in blood, serum, and different organs. The overall result of the present study indicated that EMB is toxic to fish even for a short-term exposure and low doses, and therefore utmost caution should be taken to prevent their drainage into water bodies.

Integrated biomarker approach strongly explaining in vivo sub-lethal acute toxicity of butachlor on Labeo rohita.

Butachlor herbicide belongs to the family of chloroacetanilide group, widely used for control of grass and broadleaf weeds in paddy fields however, its repeated application may result in aquatic pollution. Butachlor residue has been detected in aquatic environments, which may produce toxic effects on non-target organisms including fish. Keeping this in mind, the present study was designed to estimate the LC50 of butachlor (Shaktiman®), and to evaluate the sub-lethal toxicity at two concentrations (12.42 µg L-1 and 62.10 µg L-1) in Labeo rohita for a period of 24, 48, and 72 h. Fish exposed to butachlor reduced the counts of red blood cells (RBC), haemoglobin (HGB), hematocrit (HCT), and white blood cells (WBC). A significant (p < 0.05) increase in the antioxidant enzyme (superoxide dismutase-SOD, glutathione-s-transferase-GST), and hepatic enzyme (glutamate-oxaloacetate transaminase-GOT, glutamate-pyruvate transaminase-GPT) were noticed in butachlor exposed fish. Heat shock protein 70 (HSP70) and HSP90 in gill; cortisol, protein, albumin, globulin, and triglyceride in serum were increased upon exposure of butachlor. On the contrary, complement 3 (C3) and immunoglobulin (IgM) in serum was found to be decreased compared to control fish. The findings thus suggest that the fish upon exposure to butachlor disrupts the biomarkers which ultimately leads to growth retardation in fish.

Simultaneous determination of flubendiamide its metabolite desiodo flubendiamide residues in cabbage, tomato and pigeon pea by HPLC.

A sensitive and simple method for simultaneous analysis of flubendiamide and its metabolite desiodo flubendiamide in cabbage, tomato and pigeon pea has been developed. The residues were extracted with QuEChERS method followed by dispersive solid-phase extraction with primary secondary amine sorbent to remove co extractives, prior to analysis by HPLC coupled with UV-Vis detector. The recoveries of flubendiamide and desiodo flubendiamide were ranged from 85.1 to 98.5% and 85.9 to 97.1% respectively with relative standard deviations (RSD) less than 5% and sensitivity of 0.01 µg g(-1). The method offers a less expensive and safer alternative to the existing residue analysis methods for vegetables.

Persistence and safety risk assessment of propineb in Indian tea.

A supervised field trial was conducted on tea with propineb at 1,750 and 3,500 g a.i./ha at two locations (Assam and Darjeeling), applied thrice at an interval of 10 days during the year 2006-2007. Propineb residue was measured spectrophotometrically at 435 nm in terms of CS2. The initial deposit of propineb in green tea leaves were found to be in the range of 16.26-35.96 mg/kg and the residue persisted up to 10 days irrespective of doses and locations with half-life value ranging from 2.24 to 2.43 days and preharvest interval of 17.17-21.37 days. Made tea residues ranged from 9.27 to 20.86 mg kg(-1) on 7 days and no residues could be detected on 14 days. Infusion study indicated that propineb did not infuse into tea liquor from made tea. The limit of determination was found to be 0.1 mg kg(-1) in terms of propineb for green tea leaves, made tea, and tea liquor. The tea applied with the recommended dose of propineb is safe for consumption as liquor.

Persistence of thiacloprid and deltamethrin residues in tea grown at different locations of North-East India.

In order to examine the residues of thiacloprid (90 and 180 g a.i./ha) and deltamethrin (10 and 20 g a.i./ha) in fresh tea leaves, made tea and tea infusion, field experiments were conducted at three different locations viz. Kamalpur tea estate, Darjeeling; West Bengal, Teok tea Estate and AAU, Jorhat; Assam in India. Regardless of location and doses, residues of both the insecticides dissipated following first order kinetics. The half-life of Thiacloprid (4.93-5.38 days) was longer than that of deltamethrin (1.78-1.94 days). Processing of green tea leaves reduced the residue level of thiacloprid and deltamethrin in made tea. No residues of both these insecticides could be detected in tea infusion. With respect to the phenolic distribution in tea, a marked increase in total catechin monomers with thiacloprid and greater accumulation of EGCG and ECG (indices of phenol quality) with deltamethrin were observed.

Persistence, dissipation and consumer risk assessment of a combination formulation of flubendiamide and deltamethrin on cucumber.

Multi-location supervised field trials were conducted in India at four locations of the All India Network Project (AINP) on Pesticide Residues to study the persistence, dissipation and risk assessment of flubendiamide and deltamethrin on cucumber (Cucumis sativus). Residues of flubendiamide and deltamethrin on cucumber resulting from three spray applications of a combination formulation (flubendiamide 90% + deltamethrin 60%, 150 SC) at recommended (22.5 + 15 g a.i./ha) and double the recommended (45 + 30 g a.i./ha) dose were analysed. On the basis of persistence and dissipation studies, the half- life (T1/2) of flubendiamide on cucumber varied from 1.40 to 2.98 (recommended dose) and 1.55 to 2.76 days (double the recommended dose), while that of deltamethrin ranged from 2.5 to 4.9 (recommended dose) and 2.7 to 3.9 days (double the recommended dose) at the four locations. On the basis of supervised field trial data and using OECD calculator, MRLs in the combination product of 3 mg kg-1 for flubendiamide and 1.5 mg kg-1 for deltamethrin has been proposed for consideration by the Food Safety and Standards Authority of India (FSSAI). Codex, EU and EPA have fixed MRL of 0.2 mg kg-1 for flubendiamide and deltamethrin.

Photodecomposition of an acaricide, fenazaquin, in aqueous alcoholic solution.

Fenazaquin (I) is a new acaricide of the quinazoline class. The photodecomposition of I was studied in aqueous methanolic and 2-propanolic solution under UV light (30 h) and sunlight (70 h) separately. The photolytic half-lives in aqueous methanolic solution were found to be 17.1 h (UV) and 38.1 h (sunlight), whereas these were 12.9 h (UV) and 29.2 h (sunlight) for aqueous 2-propanolic solution; all followed a first-order reaction kinetics. Six photoproducts were obtained: beta-phenyl (p-tert-butyl) ethyl alcohol (II), 4-hydroxyquinazoline (III), p-tert-butyl vinyl benzene (IV), 2,4-dihydroxyquinazoline (V), phenyl (p-tert-butyl) acetic acid (VI), and 2-methyl-2-[4'-(2' '-hydroxyethyl)phenyl]propanoic acid (VII). Compounds VI and VII could be isolated only from aqueous 2-propanolic solution under sunlight irradiation. The major degradation products are formed as a result of cleavage of the ether bridge linking the quinazoline and phenyl ring systems of the molecule, oxidation of the tert-butyl substituent, and oxidation of the heterocyclic portion of the quinazoline ring. A probable mechanism of formation of the photoproducts is also suggested.

Residual fate and persistence of endosulfan (50 WDG) in Bengal gram (Cicer arietinum).

Residual fate and dissipation pattern of endosulfan (50 WDG) in soil and plant was studied by gas liquid chromatography following twice applications (at 350 g and 700 g a.i. ha(-1)) in chick-pea, Bengal gram (Cicer arietinum) at vegetative and flowering stages of the crop. The initial residues of Endosulfan (alpha + beta + endosulfan sulfate) in plant following second application was 23.40-57.91 microg g(-1) and its maximum deposit in soil was 1.00-2.45 microg g(-1) after 1 day. Dissipation followed first order reaction kinetics and the half-life values were 2.6-2.9 days in green foliage and 4.4-5.0 days in soil. A pre-harvest interval of 14-19 days was recommended for green foliage. No residues were detected in harvested seeds. Maximum concentration of the metabolite endosulfan sulfate was 0.152-0.473 microg g(-1) in soil and 5.42-9.40 microg g(-1) in plant on third day. Endosulfan-beta was more persistent than alpha-isomer attributable to higher conversion of the later to endosulfan sulfate in soil and plant.