A Simple Method for the Separation and Detection of Trace Levels of Buprofezin, Flubendiamide and Imidacloprid by NP-HPTLC and RP-HPTLC

A study was undertaken to evaluate the retention (R_F and R_M) and separation (ΔR_F, R^α_F , α and R_S) of buprofezin (B), flubendiamide (F) and imidacloprid (I) using n-hexane-acetone (6.5 : 3.5 v/v) in the case of NPHPTLC and methanol-water (8 : 2 v/v) for RP-HPTLC as mobile phase. The study revealed that increasing the acetone content in NP-HPTLC and decreasing the water content in RP-HPTLC resulted in high resolution with increase in RF values for B, F and I. ΔR_F > 0.04 and R_S > 1.5 were achieved for all pairs of compounds (ΔR_F(B–F) = 0.35, ΔR_F(F–I) = 0.19, ΔR_F(B–I) = 0.54, R_S(B–F) = 4.12, R_S(F–I) = 7.34, R_S(B–I) = 2.02 using NP-HPTLC; ΔR_F(F–B) = 0.23, ΔR_F(I–F) = 0.26, ΔR_F(I–B) = 0.49, R_S(F–B) = 2.63, R_S(I–F) = 2.97, R_S(I–B) = 5.92 using RP-HPTLC). Imidacloprid was adsorbed strongly on NP-HPTLC layer and buprofezin on RP-HPTLC layer, as indicated by their high R_M values. The maximum absorption of UV for B, F and I was found to be 252, 242 and 276 nm respectively. Stability analysis indicated that these compounds were stable up to 6 h in methanol and on the plates (NP-HPTLC and RPHPTLC layers). This protocol is useful for toxicologists to detect a mixture of these insecticides in forensic as well as environmental samples.