Validation, residue analysis, and risk assessment of fipronil and flonicamid in cotton (Gossypium sp.) samples and soil.

Cotton crop is highly susceptible to attack by sucking pests. Being an important oilseed and feed crop, it is essential to monitor the pesticides and ensure health protection at consumer level. Therefore, a method was validated to estimate fipronil and flonicamid in various cotton samples and risk assessment was performed. Contamination of oil in the extracts from the various oil seeds and cake samples is a major problem as this oil contaminates the column and interferes with the detection of pesticides. The present manuscript for the first time describes successful analysis of the pesticides from various cotton samples including cotton oil, seed, and cake. Quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based methods were validated for estimation of fipronil and flonicamid in cotton samples and in soil by LC-MS/MS. Recoveries were within the acceptable range of 70-120% with relative standard deviation ≤ 20% and HorRat values < 0.3-1.3. R2 was > 0.99. Matrix effects of 150 and 13.5% were observed for fipronil and flonicamid, respectively, in cotton leaves. Limits of quantitation (LOQs) were in the range of 0.0004 to 0.004 mg kg-1 for fipronil and flonicamid. Cotton samples collected from a field study at different locations were analyzed. Half-life ranged from 2.2 to 5.8 for fipronil and 4.6 to 7.0 days for flonicamid. A pre-harvest interval of 33 days is suggested. The risk assessment studies at maximum residue level values showed HQ < 1 at pre-harvest interval (PHI). The methods being short and easy can be extended to estimate more types of pesticides in different oilseeds. Following a PHI of 33 days, fipronil and flonicamid can be used on cotton at standard dose. As the levels of fipronil and flonicamid were below determination limit in all the soils, the environmental risk is negligible.

Residue decline and risk assessment of fluopyram + tebuconazole (400SC) in/on onion (Allium cepa).

A method was validated for estimating fluopyram and tebuconazole in onion on LC-MS/MS using dispersive QuEChERS. Three sprays of a combination fungicide fluopyram + tebuconazole (Luna experience, 400 SC) were applied @ 75 + 75 and 150 + 150 g a.i. ha-1 at an interval of 10 days on onion using Knapsack sprayer. First spray was made at bulb setting stage. Spring onion samples were drawn at 0 (1 h), 1, 3, 5, 7, 10, 15, and 20 days and matured onion bulb at harvest (52 days) after the last spray. Soil samples were also drawn at harvest. Foliar application of the combination product resulted in 1.14 and 2.86 mg kg-1 fluopyram residues on spring onion at standard and double dose, respectively, one hour after the last application. The levels of fluopyram residues gradually declined and recorded 0.25 and 0.58 mg kg-1 on 20th day of application with half-lives of 8.8 and 9.1 days at standard and double dose, respectively. For tebuconazole, the corresponding residues observed after 1 h (0 day) of application were 0.92 and 2.29 mg kg-1. The levels declined gradually to 0.12 and 0.33 mg kg-1 on 20th days with half-life of 6.7 to 7.7 days at standard and double dose, respectively. Here, we are proposing a pre-harvest interval of 7 day for fluopyram and tebuconazole in spring onion when applied at 75 + 75 g a.i. ha-1 (400 SC). Risk assessment was done by calculating hazard quotient and by comparing theoretical maximum residue intake (TMRI) with maximum permissible intake (MPI). In all the cases, results of the study showed that HQ (Hazard Quotient) ≤1 and TMDI < MPI. Hence, the use of this combination product can be recommended with pre harvest interval of 7 days. The data can be used in establishing MRLs (maximum residue limits) for spring onion after considering multilocation trials.

Development and validation of multiresidue analytical method in cotton and groundnut oil for 87 pesticides using low temperature and dispersive cleanup on gas chromatography and liquid chromatography-tandem mass spectrometry.

A method was developed and validated for the analysis of 87 pesticides in cotton and groundnut oil by GC with ECD and FPD detectors and LC-MS/MS. The extraction procedure based on QuEChERS followed by low-temperature freezing and dispersive cleanup steps was validated in two oil matrices for 87 pesticides of different classes. Linearity, expressed as coefficient of variation, was within the acceptable range. Of those tested, 77-83 and 77-89% pesticides showed recoveries within the acceptable range of 70-120% on LC-MS/MS in cottonseed oil and groundnut oil, respectively, at different spiking levels. In case of GC analysis, 63-65 and 53-82% pesticides showed recoveries within the acceptable range of 70-120% on GC in cottonseed oil and groundnut oil, respectively, at different spiking levels. The exceptions to these recoveries were the few organochlorines which consistently gave lower recoveries. Recovery factors can be employed while analysing these pesticides by this method as the results obtained were consistent in both oils. RSD was less than 20% for most of the pesticides. The calculated limit of quantitation (LOQ) for most of the pesticides satisfies the maximum residue level (MRL) requirements as per European Union (EU) guidelines and Food Safety and Standards Authority of India (FSSAI).

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 in/on Brinjal (Solanum melongena) fruits.

A field experiment was conducted at Anand Agricultural University, Anand during Sept-Dec, 2009 to study the rate of degradation of flubendiamide in/on brinjal fruits following foliar application of Fame 480 SC at 90 (standard dose) and 180 (double dose) g a.i. ha( -1). The residues estimated using HPLC revealed persistence of flubendiamide in/on brinjal till 3rd and 7th day after the last spray at standard and double dose, respectively. The residues of flubendiamamde were reported as parent compound, and no desiodo metabolite was detected. The initial deposits of 0.17 and 0.42 µg g( -1) in/on brinjal fruits reached below determination level of 0.05 µg g( -1) on the 5th and 10th day at standard and double dose, respectively. The half life of flubendiamide on brinjal fruits ranged from 2.68 to 2.55 days. Soil samples analyzed on the 15th day after the last spray revealed residues at below determination level (0.05 µg g( -1)) at either dose of application.