Atrazine molecular imprinted polymers: comparative analysis by far-infrared and ultraviolet induced polymerization

Abstract

Atrazine molecular imprinted polymers (MIPs) were comparatively synthesized using identical polymer formulation by far-infrared (FIR) radiation and ultraviolet (UV)-induced polymerization, respectively. Equilibrium binding experiments were carried out with the prepared MIPs; the results showed that MIP(uv) possessed specific binding to atrazine compared with their MIP(FIR) radiation counterparts. Scatchard plot's of both MIPs indicated that the affinities of the binding sites in MIPs are heterogeneous and can be approximated by two dissociation-constants corresponding to the high- and low-affinity binding sites. Moreover, several common pesticides including atrazine, cyromazine, metamitron, simazine, ametryn, terbutryn were tested to determine their specificity, similar imprinting factor (IF) and different selectivity index (SI) for both MIPs. Physical characterization of the polymers revealed that the different polymerization methods led to slight differences in polymer structures and performance by scanning electron microscope (SEM), Fourier transform infrared absorption (FT-IR), and mercury analyzer (MA). Finally, both MIPs were used as selective sorbents for solid phase extraction (SPE) of atrazine from lake water, followed by high performance liquid chromatography (HPLC) analysis. Compared with commercial C18 SPE sorbent (86.4%-94.8%), higher recoveries of atrazine in spiked lake water were obtained in the range of 90.1%-97.1% and 94.4%-101.9%, for both MIPs, respectively.

Figure 1.

SEM of MIPs and NIPs prepared by FIR- and UV-polymerization methods.

Figure 2.

Comparative IR spectra of prepared materials by FIR- and UV-polymerization methods.

Figure 3.

Comparative pore-size distribution of both FIR- and UV-polymerization polymers.

Figure 4.

Comparison of equilibrium absorption obtained in separated experiments for both FIR and UV polymerization polymers.

Figure 5.

Scatchard plot over 0.1–1.6 mmol/L concentration range for FIR- (A) and UV-polymerisation materials (B).

Figure 6.

Molecular structure of six analytes for the specificity study.

Figure 7.

Comparative HPLC chromatograms of the spiked lake water of atrazine with a final concentration 5 mg/L on MIP-SPE and C₁₈-SPE columns.

Figure 8.

Schematic representative of preparation of atrazine imprinted polymers for SPE.