Rapid Determination of Acetamiprid in Chinese Herbal Medicine by Visualization Method Based on Aptamer with Gold Nanoparticles as Optical Probe

Using the pesticide acetamiprid aptamer as recognition element and gold nanoparticles as color indicator, a method of gold nanoparticles as optical probe based on the acetamiprid aptamer was established to specifically determine the content of acetamiprid in Chinese herbal medicines. The target compound in the sample was ultrasonically extracted with methanol. After centrifugation, the supernatant was purified with anhydrous MgSO₄ and N-propyl ethylenediamine. After the gold nanoparticles solution together with the acetamiprid aptamer were reacted at room temperature for 15 min, the sample solution was taken and added to react with the above solution for 20 min. 200 mmol·L^-1 NaCl solution was added, and the mixture was kept under steady condition for 5 min. In a high-salt environment, acetamiprid had a specifical interaction with the aptamer, gold nanoparticles aggregated due to loss of aptamer protection, and the color of the system changed from red to blue. A multifunctional microplate reader was used to measure the absorbance of the above system at 520, 650 nm. The results showed that linearity relationship was kept in the range of 20-200 μg·L^-1 between mass concentration of acetamiprid and the ratio of absorbance at 520 nm and 650 nm, with detection limit of 1.13 μg·L^-1. A spkied recovery test was made on the blank Chinese herbal medicine at 3 concentration levels, giving recoveries ranged from 91.1% to 105%, and RSDs (n=5) of measured values ranged from 1.1% to 4.8%. The proposed method was used for determination of acetamiprid in a variety of Chinese herbal medicines, and acetamiprid was detected in the 2 Chinese herbal medicines, with detection mass fractions of 329.10, 125.22 μg·kg^-1.