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, alpha-cypermethrin, and lambda-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 microg, 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.