Synthesis, characterization and application of dummy-template molecularly imprinted microspheres for 2,4-d butyl ester

ABSTRACT

Dummy-template molecularly imprinted microspheres were synthesized via precipitation polymerization employing 2,4-D isooctyl ester as the template molecule instead of 2,4-D butyl ester, while methacrylic acid and divinylbenzene were used as functional monomer and cross-linker in acetonitrile or a mixture of acetonitrile and toluene. The microspheres were characterized by scanning electron microscopy, laser particle size analyzer and fourier transform infrared spectrometry. Binding capacity experiment showed that the molecularly imprinted polymers prepared in a mixture of acetonitrile and toluene had a high binding capacity. The performance of microspheres was further assessed by equilibrium binding and kinetic adsorption experiments. The results showed that the apparent maximum adsorption reached up to 1.35 mg·g⁻¹ within 10 min. Based on the dummy-template microspheres, a molecularly imprinted solid phase extraction-gas chromatography method was developed for the selective analysis of 2,4-D butyl ester in soil samples. The mean recoveries of 2,4-D butyl ester from blank soil samples ranged from 85.9 to 99.3% with relative standard deviations of 4.5–14.3% (n = 5). The limit of detection and the limit of quantification of 2,4-D butyl ester were 0.8 μg·kg⁻¹ and 2.3 μg·kg⁻¹, respectively.

KEYWORDS:

• 2,4-D butyl ester
• dummy molecularly imprinted microspheres
• molecularly imprinted solid phase extraction
• precipitation polymerization