Abstract:

To evaluate the commercial test kits for pesticide residue rate and understand their quality, the sensitivity of six brands of pesticide residue rapid test kits sold in market to phorate, phoxim, diazinon, parathion and moncrotophos were determined in two cases (2.5 mL and 3 mL of extract). The effect curves of inhibition rate on pesticide concentration of the kits were plotted according to the determination results of the five pesticides at five concentration levels, the logarithm of inhibition rate and pesticide concentration were used for linear fitting, and the correlation coefficient, IC₅₀ and IC₁₀ were calculated, the sensitivity of various kits to each pesticide were compared according to IC₁₀. Then the advantages and disadvantages of the kits were determined. The sensitivity of the same kit to different pesticides and different kits to the same pesticide were different. The kits with better logarithmic correlation between inhibition rate and pesticide concentration had correlation coefficient R² of 0.4835-1 (2.5 mL of extract) and 0.6602-1 (3 mL of extract); and IC₁₀ was 2.01×10^-4-3.78 mg/kg (2.5 mL of extract) and 3.92×10^-3-3.36 mg/kg (3 mL of extract) respectively. The six kits were not sensitive to phorate. Except kit A, the inhibition rates of the other kits at five concentration levels were 0. According to the five pesticides tested, the kits are divided into three grades. D kit is the best, followed by C and E, and the third is A, B and F. It is suggested to modify the judgment threshold of 50% or 70% of the national standard and industrial standard.

Key words: test kit, pesticide, semi-inhibition concentration, detection limit, sensitivity, linear range