Grafting of Molecularly Imprinted Polymers on to Carboxyl-Modified Multiwalled Carbon Nanotubes for the Extraction of Rhodamine B from Dried Chili Powder

Abstract

Molecularly imprinted polymers grafted on to the surface of carboxyl-modified multiwalled carbon nanotubes were developed using methacrylic acid as a functional monomer and trihydroxymethylpropyl trimethylacrylate as a crosslinker for application to rhodamine B determination. The synthesis, characteristics, and evaluation of the molecularly imprinted polymer are described. The apparent morphology of the polymers was characterized by scanning electron microscopy. To evaluate the binding ability of the molecularly imprinted polymers, equilibrium binding experiments were conducted and revealed the maximal binding capacity to be 561.54 µg g⁻¹. The introduction of nanomaterials into the polymer composite made important contributions to the affinity enhancement and recognition properties of the molecularly imprinted polymers. Moreover, the polymers were preliminarily applied as an adsorbent for separation and extraction of Rhodamine B from dried chili powder samples, based on solid phase extraction technology. The calibration curve was linear in the range of 0–7 µg mL⁻¹. For all tested samples, recoveries were reliable and in the range of 101.75–109.73%. The relative standard deviation ranged from 6.43–14.32%, which demonstrated that the polymer has potential for preconcentration of Rhodamine B from chili powder samples.

Keywords:

• Dried chili powder
• Molecularly imprinted polymers
• Multiwalled carbon nanotubes
• Rhodamine B
• Solid phase extraction

Notes

^a Average of three determinations by using MIP ± SD.