Release kinetics of controlled release formulations of thiamethoxam employing nano-ranged amphiphilic PEG and diacid based block polymers in soil

Abstract

Amphiphilic copolymers, synthesized from poly(ethylene glycols) and various aliphatic and aromatic diacids, which self-assemble into nanomicellar aggregates in aqueous media, were used to develop controlled release (CR) formulations of thiamethoxam (3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine) using encapsulation technique Formulations were characterised by Infrared (IR) spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscope (TEM). Encapsulation efficiency, loading capacity and stability after accelerated storage test of the developed formulations were checked. The kinetics of thiamethoxam, released in sandy loam soil from the different formulations was studied. Release from the commercial formulation was faster than the CR formulations. The time taken for release of 50 % of thiamethoxam ranged from 3.56 to 6.07 days for the CR formulations. Although the diffusion exponent (n value) of thiamethoxam in soil ranged from 0.532 to 0.881 in the tested formulations showing non-Fickian transport. These CR formulations may be used in safer, effective and economic crop protection.

Dissipation dynamics of clothianidin and its control efficacy against Bradysia odoriphaga Yang and Zhang in Chinese chive ecosystems

“…The field dissipation rate of pesticides in soil is dependent on factors such as their applied dosages, soil characteristics, climatic conditions, daylight hours, presence and types of crops and use of fertilisers, 31 which, when taken all together, led to the differences in the half-life of clothianidin in the aforementioned studies. For example, Guzsvany et al 32 found that low temperatures and low pH could reduce the dissipation of neonicotinoids, and Sarkar et al 33 also found that the use of the formulated product could lead to a different dissipation rate, with power formulations persisting longer than liquid formulations. The dissipation time of neonicotinoids in soils with cover crops was more rapid than in bare soils, 34 and the variety of cover crops could also affect pesticidal dissipation.…”

Macroporous open cell polyester amphigel using citric acid and PEO: Solvent absorption, thermal behavior, and slow release of pesticide

“…The kinetics of imidacloprid release from CAPEO-I in water was assessed by previously reported methods. 22,23 Briefly, the known quantity of CAPEO-I(0.2 g) was taken in nylon bags (3 cm × 3 cm) and immersed in deionized water having neutral pH (6.9). The setup was incubated at 30 ± 2 C and at selected time an aliquot (20 μl) (passed through 0.45 μm filter) was injected to HPLC to analyze the amount of imidacloprid released.…”

“…To describe the release behavior of bioactive molecules from a controlled release system these two models had been used extensively. 22,23,[26][27][28]…”

“…These methylene protons appear downfield compared to the corresponding methylene protons of PEO thereby confirming the formation of the ester linkage. 23 The FT-IR spectra of the CA, PEO-600 and CAPEO-600 are presented in Figure 2(a), which shows that CA showed two strong bands at 1739 and 1681 cm −1 due to conformational mixture of its anhydride and free carboxylic acid, respectively (Figure 2(a)). 30 The oxyethylene chain of PEO-600 showed two strong bands at 1091 cm −1 and 2864 cm −1 due to -C-O-Cand C-H stretching vibrations (Figure 2(a)ii).…”

Application Of Nanotechnology In Agriculture And Food Industry, Its Prospects And Risks

“…Controlled-release formulations based on PEGs-amphiphilic copolymers were prepared with thiamethoxam [186], thiram [187], carbofuran [188], β-cyfluthrin [189] and imidacloprid [190]. In these formulations the release rates increase with increasing PEG molecular weight.…”