Spectrophotometer is a commonly used and basic analytical technique that can be used for both quantitative and qualitative examination in chemical, pesticides and other materials. In this work, it was studied that spectral-density (S-D) curve, calibration density (C-D) curve and quantification limits for fipronil and neonicotinoids insecticides in acetonitrile solvent on UV-Vis Spectrophotometer (Thermo Corporation, Nicolet, evolution 100) were maximum absorption (λ max ) equal 208, 256, 269 and 246 nm for fipronil, thiamethoxam, imidacloprid and acetamiprid, respectively. The slope and R2 were 0.059 and 0.9545 for fipronil, 0.044 and 0.9989 for thiamethoxam, 0.046 and 0.999 for imidacloprid and 0.249 and 0.9996 for acetamiprid, respectively. The limit of blank (LOB), limits of detection (LOD), and quantification (LOQ) were found to be 0.