An efficient analytical method for analysis of spirotetramat and its metabolite spirotetramat-enol by HPLC.

Spirotetramat is a new compound which belongs to the chemical class of ketoenols. As per the available literature analysis of spirotetramat and its metabolites spirotetramat-enol is carried out by high pressure liquid chromatograph with mass spectrometry (HPLC-MS/MS). In this study we have standardized a method where analysis of both the compounds is carried out by HPLC. The extraction and cleanup of spirotetramat and its metabolites spirotetramat-enol was carried out by QuEChERS method. The cleaned up residues were estimated by HPLC equipped with a photo diode array detector at a wavelength of 250 nm. The mobile phase used was acetonitrile: water at a proportion of 40:60. The limit of quantification (LOQ) of the method was 0.05 mg kg(-1) for both spirotetramat and its metabolite spirotetramat-enol. The recoveries of both the compounds at the LOQ level were in the range of 72.72%-86.76% from mango and 74.82% to 86.92% from cabbage.

Development of an analytical method for analysis of flubendiamide, des-iodo flubendiamide and study of their residue persistence in tomato and soil.

Flubendiamide is a new insecticide that has been found to give excellent control of lepidopterous pests of tomato. This study has been undertaken to develop an improved method for analysis of flubendiamide and its metabolite des-iodo flubendiamide and determine residue retention in tomato and soil. The analytical method developed involved extraction of flubendiamide and its metabolite des-iodo flubendiamide with acetonitrile, liquid-liquid partitioning into hexane-ethyl acetate mixture (6:4, v v⁻¹) and cleanup with activated neutral alumina. Finally the residues were dissolved in gradient high pressure liquid chromatography (HPLC) grade acetonitrile for analysis by HPLC. The mobile phase, acetonitrile-water at 60:40 (v v⁻¹) proportion and the wavelength of 235 nm gave maximum peak resolution. Using the above method and HPLC parameters described, nearly 100 % recovery of both insecticides were obtained. There was no matrix interference and the limit of quantification (LOQ) of the method was 0.01 mg kg⁻¹. Initial residue deposits of flubendiamide on field-treated tomato from treatments @ 48 and 96 g active ingredient hectare⁻¹ were 0.83 and 1.68 mg kg⁻¹, respectively. The residues of flubendiamide dissipated at the half-life of 3.9 and 4.4 days from treatments @ 48 and 96 g a.i. ha⁻¹, respectively and persisted for 15 days from both the treatments. Des-iodo flubendiamide was not detected in tomato fruits at any time during the study period. Residues of flubendiamide and des-iodo flubendiamide in soil from treatment @ 48 and 96 g a.i. ha⁻¹ were below detectable level (BDL, < 0.01 mg kg⁻¹) after 20 days. Flubendiamide completely dissipated from tomato within 20 days when the 480 SC formulation was applied at doses recommended for protection against lepidopterous pests.

Behavior of beta cyfluthrin and imidacloprid in/on mango (Mangifera indica L.).

Residue persistence of beta cyfluthrin and imidacloprid on mango was carried out after giving spray application of the combination formulation, beta cyfluthrin 9% + imidacloprid 21% (Solomon 300 OD) 3 times at the fruit formation stage. The treatments were, untreated control, standard dose of 75 g a.i. ha(-1) and double dose of 150 g a.i. ha(-1). Initial residues of beta cyfluthrin on mango fruits were 0.04 and 0.12 mg kg(-1) from treatments at the standard and double doses, respectively. The residues dissipated with the half-life of 2.4 and 2.6 days and persisted for 5 days only. Initial residues of imidacloprid on mango fruits were 0.14 and 0.18 mg kg(-1) from treatments at the standard and double doses, respectively. Imidacloprid residues degraded with the half-life of 3.06 and 4.16 days, respectively and persisted for 10 days. Mature mango fruits at harvest were free from residues of both insecticides. A safe pre-harvest interval of 8 days is recommended for consumption of mango fruits after treatment of the combination formulation.

Persistence and dissipation of flubendiamide and des-iodo flubendiamide in cabbage (Brassica oleracea Linne) and soil.

Flubendiamide belongs to a novel class of insecticide which controls lepidopteran pest complex of cabbage such as diamondback moth, cabbage white butterfly, cluster caterpillar etc. Being a newly introduced insecticide no information is available on its residue persistence in cabbage. A study was undertaken to evaluate the residue persistence of flubendiamide in cabbage and soil following 2 applications of flubendiamide 480 SC at the recommended and double the recommended dose of 24 and 48 g a.i. ha(-1). Initial residue deposits of flubendiamide in cabbage were 0.33 and 0.49 mg kg(-1) respectively. The residues persisted for 10 days from the both the treatments and dissipated with the half-life of 3.9 and 4.45 days, respectively. Des-iodo flubendiamide, a metabolite of flubendiamide, was not detected in cabbage at any time during the study period. Soil sample collected from the treated field after 15 days was free from any residue of flubendiamide or its metabolite.

Behaviour of trifloxystrobin and tebuconazole on grapes under semi-arid tropical climatic conditions.

BACKGROUND: A mixture of trifloxystrobin and tebuconazole is excellent in controlling both powdery and downy mildew of grapes. The objective of the present work was to study the behaviour of trifloxystrobin and tebuconazole on grape berries and soil following treatment with Nativo 75 WG, a formulation containing both fungicides (trifloxystrobin 250 + tebuconazole 500 g kg(-1)). This study was carried out for planned registration of this mixture for use on grapes in India. RESULTS: Initial residue deposits of trifloxystrobin and tebuconazole on grapes were below their maximum residue limit (MRL) of 0.5 and 2 mg kg(-1), respectively, when Nativo 75 WG was applied at the recommended dose of 175 g product ha(-1). The residues dissipated gradually to 0.02 and 0.05 mg kg(-1) by 30 days, and were below the quantifiable limit of 0.01 mg kg(-1) at the time of harvest (60 days after the last treatment). Trifloxystrobin and tebuconazole dissipated at a pre-harvest interval (PHI) of 36 and 34 days, respectively, from the recommended treatment dose. The acid metabolite of trifloxystrobin, CGA 321 113, was not detected in grape berries at any point in time. Soil at harvest was free of any pesticide residues. CONCLUSION: Residue levels of both trifloxystrobin and tebuconazole were below MRLs when grapes were harvested 30 days after the last of four applications of 175 g product ha(-1) (trifloxystrobin 44 g AI ha(-1), tebuconazole 88 g AI ha(-1)) under the semi-arid tropical climatic conditions of India.