Method validation, dissipation and residue status of fluopicolide and fosetyl-aluminium in citrus using a rapid extraction method coupled with ultra-performance liquid chromatography-tandem mass spectrometry.

The dissipation and residue status of a combination of fluopicolide and fosetyl-aluminium (fosetyl-Al) in citrus were evaluated in an experimental field. An efficient and sensitive liquid chromatography-tandem mass spectrometry, with rapid extraction, was carried out according to the SANTE guidelines. During the method validation, the recovery was within the range of 106.1-117.5, 94.4-115 and 85.4-109.5%, for fluopicolide, its metabolite 2,6-dichlorobenzamide and fosetyl-Al, respectively, with a relative standard deviation (RSD) of 0.3-10.6%. As a result, accuracy and precision at the spiking concentrations of 0.01, 0.05 and 0.10 mg/kg in citrus were within the acceptable range of 70-120% with an RSD of 20%. The amount of the deposits of fluopicolide, 2,6-dichlorobenzamide and fosetyl-Al was less than the limit of quantification (LOQ) at 0.01 mg/kg at 0 day, adhering to the application in standard [1.77 + 2.66 g of active ingredient (a.i.)/L] and double (3.54 + 5.32 g a.i./L) doses. The present study proposes that the utilisation of fluopicolide and fosetyl-Al in citrus and the soil may not pose a health or environmental hazard provided that good agricultural practices are followed.

Analytical method development, validation and study on behaviour of ipfencarbazone in paddy (rice).

Supervised field trial was conducted to study persistence of a pre-emergent herbicide, ipfencarbazone (25% SC) on rice crop. Single application of two different doses, 156.25 g a.i.ha-1/625 mL formulationha-1 and 312.50 g a.i.ha-1/1250 mL formulationha-1, was applied. Method was validated to analyse ipfencarbazone in rice samples (leaf/plant, grain, straw and husk) and in soil. Initial accumulation of ipfencarbazone in rice plants was 6.72 and 14.71 mg kg-1 in standard and double dose, respectively. The residues decreased linearly with r2 values of 0.92 and 0.98 in different doses and reached below limit of quantitation (LOQ) of 0.01 µg kg-1 (for rice plant/leaf) and 0.05 µg kg-1 (for rice grain, husk, straw) on 30th and 97th (harvest) day respectively after application in both the doses. An average half-life of ipfencarbazone was approximately 4 days. Less than LOQ levels at harvest and short half-life suggest that the use of ipfencarbazone is safe, provided good agricultural practices (GAP) are followed. The data can be used by regulatory authorities like Food Safety and Standards Authority of India (FSSAI) and CODEX for establishing maximum residue limits (MRLs) of ipfencarbazone.

Development, validation and evaluation of matrix effect of a QuEChERS-based multiresidue method with low temperature dispersive clean-up for analysis of 104 pesticides in cumin (Cuminum cyminum) by LC-MS/MS.

BACKGROUND: Until now, there is no method available for analysis of pesticide residues in complex matrices like spices. Therefore, there is an urgent need to develop and validate a QuEChERS-based method for the estimation of 104 pesticides in cumin seed. RESULTS: Samples were spiked for 109 pesticides at concentrations of 0.1, 0.5 and 1.0 mg kg-1 . Of these 104 pesticides were recovered. At 0.1, 0.5 and 0.1 mg kg-1 , recoveries ranged from 71% to 108% when compared with matrix matched standards. Seventeen pesticides showed higher or lower recoveries than acceptable range (70-120%) when quantified using solvent standards showing significant matrix effect (ME) (≥ ±20%) even after 20× dilution. However, for the other pesticides ME was significantly eliminated on dilution. The recovery percentage improved for all pesticides on quantitation with matrix matched standards when compared with solvent standards. For pesticides with lower European Union (EU) maximum residue limits (MRLs), an experiment at lower spiking concentrations of 0.01 and 0.05 mg kg-1 with lower dilutions (8×) reveals that almost all pesticides with lower EU MRLs (0.02 and 0.05 mg kg-1 ) showed recoveries in the range 74-124% and relative standard deviation (RSD) less than 20%. CONCLUSION: Theoretical limit of quantitation (LOQ) is proposed which ranged from 0.01 to 0.18 mg kg-1 for matrix matched standards. An LOQ of 0.01 mg kg-1 was easily achieved for the pesticides with lower EU MRLs with lower dilutions (8×) with exception of fipronil for which this can be achieved without dilution provided matrix matched standards are used. The method can be extended to other spices. © 2021 Society of Chemical Industry.

Evaluation of Matrix Effects in Multiresidue Analysis of Pesticide Residues in Vegetables and Spices by LC-MS/MS.

The study was conducted to investigate matrix interferences using QuEChERS sample preparation to understand whether the dilution of matrix and/or the grouping of commodities can eliminate the need for selective individual matrix-matched standards in LC with tandem MS (MS/MS) analysis, and whether the calibration graph based on only one matrix can be used for quantification in the other matrixes. Matrix effects (MEs) were studied by comparing the slopes of calibration curves of the matrix-matched standards (diluted with mobile phase) vis-à-vis the solvent-based standards. The present study showed that MEs were dependent on the nature of both the commodity and the analyte. Among the test matrixes, the highest variability in ME was recorded in capsicum. Most of the pesticides showed signal suppression in tomato, capsicum, and cumin matrixes. In brinjal matrix, the signal of most of the pesticides showed slight enhancement. Due to the similar nature of the MEs in tomato and capsicum, these two commodities can be grouped together. Considering analyte variability, acetamiprid, 3-hydroxy carbofuran, dichlorvos, dimethoate, and spinosyn A and D showed no significant ME (≤20%) in tomato. Very high MEs (2360.9 and 1250.8%) were observed for quizalofop-p-tefuryl and tebuconazole, respectively. To check the effect of dilution in minimizing the ME, cucumber and brinjal matrixes were diluted 10×, and calibration curves were drawn with five concentration levels. It was found that about 60% of the total analyzed pesticides showed MEs ≤20%. In cumin, MEs ranged from -5.3% for triazophos to 661% for thiacloprid. Most of the pesticides showed recoveries in the acceptable range of 70-130% with calibration curves from both matrixes. To compensate for MEs, it is suggested that (1) tomato and capsicum matrixes, which show similar trends, can be grouped together; and (2) cucumber matrix, when diluted 10×, can be used to prepare calibration curves for the quantification of pesticides in various fruiting and cucurbit vegetable matrixes by LC-MS/MS.

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).