Thermal and other analytical studies on bifenthrin urea co-inclusion complex

Abstract

In current study, thermal and other analytical techniques have been successfully utilized in characterization of bifenthrin urea co-inclusion complex (BNUCIC)—a human-guarded insecticide formulation. Bifenthrin (BN)—a widely used pyrethroid insecticide was successfully engulfed in the cavities of hexagonal urea lattice in the presence of a suitable rapidly complexing agent (RCA). Resulting formulation shields human beings from insecticides through direct inhalation, ingestion or dermal contact. Insects will be exposed to insecticide only after BNUCIC comes in contact with water in soil/crops following switching on of water sprinkling/distribution system in the fields. Formation of BNUCIC was characterized by DSC, FTIR, XRD and 1H-NMR studies. Thermal analysis played a key role in characterization, in estimation of the minimum proportion of RCA needed for complexation and to study the influence of relative proportion of RCA on heat of decomposition of complexes. Thermal analysis depicted gradual increase in heat of decomposition of BNUCIC and excellent r2 value with increasing molar fraction of linear chain RCA. Increased heat of decomposition ensures improved physical stability of complexes. Overlay of DSC curves of BNUCIC complexes revealed absence of melting endotherm of insecticide indicating amorphous nature of BN. FTIR spectrum and XRD diffractogram depicted characteristic peaks and interplanar spacings of hexagonal urea. 1H-NMR spectrum revealed presence of exposed protons of guest moieties in hexagonal urea. BNUCIC exhibited uniform formulation composition and improved dissolution profile. Studies reveal insecticide–fertilizer amalgamation to be a useful technique for formulation of an effective human-guarded insecticide formulation with improved characteristics.