Adoption of new strategy for molecularly imprinted polymer based in-tube solid phase microextraction to improve specific recognition performance and extraction efficiency

In-tube solid phase microextraction (IT-SPME) utilizing molecularly imprinted polymers (MIPs) as extraction phase has received wide attention due to various merits. However, low extraction efficiency and unsatisfactory recognition performance have limited its extensive application. To circumvent the limitations, a new strategy that implementation of magnetic fields during extraction stage was introduced to improve the extraction efficiency and recognition performance of MIPs-based IT-SPME. Firstly, using 2,4-dinitroaniline (2,4-DNA) as model template, a MIP mingled with magnetic nanoparticles (Fe3O4) was in-situ prepared in a capillary and employed as the microextraction column of IT-SPME. In the second step, a magnetic coil was wrapped the as-prepared MIP-based microextraction column so as to produce variable magnetic fields in extraction step. Results revealed that the application of magnetic field during the adsorption step improved the specific extraction performance towards template. The extraction efficiency and imprinting factor towards 2,4-DNA increased from 58% and 2.5 to 81% and 3.1, respectively. Practicality of the introduced magnetism-assisted IT-SPME technique based on MIP was demonstrated by on-line hyphenating with HPLC/DAD to quantify trace 2,4-DNA in a variety of environmental waters. High sensitivity (limit of detection was 0.060 μg/L), good precision (RSDs were below 10%) and satisfactory recoveries (82.1–111%) were obtained. Furthermore, the possible selective extraction mechanism under magnetic fields was deduced.