Dissipation and risk assessment of Solomon (300 OD), a combination product of beta-cyfluthrin and imidacloprid in lemon and onion samples

Supervised field trials were conducted to study dissipation of combination product of beta-cyfluthrin and imidacloprid (Solomon) in various samples of lemon and onion. The pesticides were extracted and analysed using QuEChERS (with some modifications) based methods after validation of the method. Linearity, accuracy and precision data showed that the results were in the acceptable range as per SANTE 2019. The results of dissipation revealed that the initial accumulation of beta-cyfluthrin was 0.6 and 1.1 mg kg−1 in lemon and 0.24 and 0.97 mg kg−1 in onion samples at standard and double dose respectively. The residues of imidacloprid were 2.61 and 4 mg kg−1 in lemon and 0.36 and 0.53 in onion at two doses. The residues of beta-cyfluthrin followed first order dissipation in both the crops at standard dose and showed biphasic dissipation in double dose in both lemon and onion samples. Imidacloprid followed first-order dissipation in lemon in both the doses. Half-life of beta-cyfluthrin ranged from 3.6 to 23.2 days in lemon samples and that of imidacloprid was 15.1 and 21.5 days in two different doses. In onion the half-life ranged from 2.1 to 4.0 for beta-cyfluthrin and 2.8 to 5.2 days for imidacloprid in different doses. Theoretical maximum residue concentration (TMRC) was always less than maximum permissible intake (MPI) in all the samples suggesting that the use of combination product is safe.