Separation of cis- and trans-cypermethrin by reversed-phase high-performance liquid chromatography

As a pyrethroid insecticide, cypermethrin (CP) possesses three chiral centers and thus consists of eight optical isomers. High-performance liquid chromatography (HPLC) methods have been established for the separation and determination of pyrethroid insecticides. In this article, we report a new reversed-phase high-performance liquid chromatography (RP-HPLC) method of separating the diastereomers of CP. Our method was performed on a C18 column with the following specifications: mobile phase, methanol/acetonitrile/water (58:18:24, v/v/v); flow rate, 1.0 mL/min; column temperature, 20°C and UV-detection wavelength, 235 nm. The results showed that the applied procedure was linear based on calibration curves with equation (y = 16.595x + 1.7892) within the CP concentration range of 5-100 mg/L. The limit of detection and limit of quantification of CP were 0.2 and 0.7 mg/L, respectively. CP or β-CP extracted from the microbial degradation system was determined, and the method was proved to be accurate and applicable. Therefore, the proposed RP-HPLC method was simple, inexpensive and can be used to study stability and determine CP residues in pharmaceutical preparations or in the environment.