Assessment of methyl ester as a green carrier solvent in pesticide emulsifiable concentrate formulation

The conventional pesticide emulsifiable concentrate (EC) formulations usually contain a large amount of aromatic solvents. This causes adverse effects to environment and human health due to the toxicity of such organic solvents. In this study, a cypermethrine 25EC formulation was developed using methyl ester as a green solvent. The physicochemical characterizations, emulsion properties and storage stabilities of the methyl ester EC formulations were investigated and compared with those of the EC formulation using naphtha A100 as a solvent, evidencing excellent emulsion properties and storage stabilities of such methyl ester EC formulations.

Residual efficacy of cypermethrin and pirimiphos-methyl against Sitophilus granarius (L.) and Plodia interpunctella (Hübner) on concrete surface

Residual activity of EC formulations of two insecticides, cypermethrin (combined with the synergist piperonyl butoxide) and pirimiphos-methyl, against Sitophilus granarius (L.) adults and Plodia interpunctella (H?bner) larvae was investigated on concrete surface. The experiment was run indoors at 16-24?C temperature and 30-60% r.h. by applying water solutions of products based on cypermethrin (48 mg AI/m2) and pirimiphos-methyl (750 mg AI/m2) to concrete surface. Insect mortality was estimated after 2, 7 and 14 days of insect exposure to treated concrete and 7 days of recovery on untreated coarse wheat meal at 24-26?C and 55-65% r.h in the laboratory. High efficacy of cypermethrin against S. granarius adults (87-100%) and P. interpunctella larvae (84-100%) was detected after 14 days of exposure to all deposits on concrete surface. Pirimiphos-methyl achieved maximum efficacy (100%) in all treatments of S. granarius adults and P. interpunctella larvae after 2 and 14 days of exposure, regardless of deposit age. After 7 days of recovery, the efficacy of both insecticides mostly increased, especially of cypermethrin, up to around 50% after two days of exposure, up to 24-45% after seven days of exposure and up to 15% after 14 days of exposure. The results show that the EC formulations of cypermethrin and especially of pirimiphos-methyl were highly effective in controlling S. granarius adults and P. interpunctella larvae over a period of 60 days following application to concrete surface.

Determination of Active Ingredient in Synthetic Pyrethroid Formulations by High-Performance Thin-Layer Chromatography/Densitometry

A new, simple, precise, and rapid high-performance thin-layer chromatography (HPTLC) method was developed for the analysis of commercial emulsifiable concentrate (EC) formulations of cypermethrin, α-cypermethrin, and λ-cyhalothrin. A known amount of reference grade synthetic pyrethroid and its EC formulation was subjected to TLC, and the amount of pesticide present in the active ingredient spot was estimated by densitometry in a single beam, single wavelength reflectance mode. Calibration curves of the synthetic pyrethroid was linear in the range of 8–24 μg, and the correlation coefficient for the calibration equation ranged between 0.97 and 0.99. Recoveries from laboratory-prepared test samples of the EC formulation were in the range of 95–99%. Pesticide formulations were further analyzed by gas liquid chromatography using flame ionization detector, and results were comparable. The proposed HPTLC method has application for quality control and determination of the shelf life of EC formulations.