Preparation and Characterization of Metolachlor Molecularly Imprinted Polymer Coating on Stainless Steel Fibers for Solid-Phase Microextraction

Abstract

A molecularly imprinted polymer (MIP) with metolachlor as the template molecule was first coated on the surface of stainless steel fibers through chemical bonding. Despite 12 times repeated coating procedures, a homogenous, porous, and highly cross-linked MIP coating was obtained with thickness of 17.4 µm (RSD of 6.1%). The specific selectivity of MIP coating to metolachlor and three metabolites could be concluded with 4.4, 4.1, 3.9, and 2.9 times higher extraction amounts of metolachlor, hydroxymetolachlor, deschlorometolachlor, and desmethylmetolachlor than that of the NIP coating, respectively, and good extraction capabilities for chloroacetanilide herbicides were found with the MIP-coated SPME stainless steel fiber. For validation, the fiber was applied for the extraction of metolachlor, propisochlor, and butachlor in spiked corn and soybean samples, and the recoveries of 90.7–92.6%, 86.4–87.9, and 85.4–87.5% were obtained, respectively.

Keywords:

• Coating
• Metolachlor
• Molecularly imprinted polymer
• Solid-phase microextraction
• Stainless steel fiber

Acknowledgments

The authors would like to thank the National Natural Science Foundation of China for the financial support of this research under the grant number of 20905026.

Notes

–: The condition was same with that used in MIP-1 preparation.

^a Extraction conditions: 0.67 mg/L metolachlor in hexane of 0.15 mL was extracted with MIP- or NIP-coated stainless steel fiber for 120 min; desorption was performed in methanol of 0.15 mL for 30 min; injection volume for HPLC analysis was 10 µL.

^b Selectivity coefficient was valuated with the ratio of extraction amount of MIP coating to its corresponding NIP coating.