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Behavior of phenols and phenoxyacids on a bisphenol-A imprinted polymer. Application for selective solid-phase extraction from water and urine samples.

Herrero-Hernández E, Carabias-Martínez R, Rodríguez-Gonzalo E - Int J Mol Sci (2011)

Bottom Line: In an aqueous medium, hydrophobic interactions were found to exert a remarkably non-specific contribution to the overall binding process.Several parameters affecting the extraction efficiency of the BPA-MIP were evaluated to achieve the selective preconcentration of phenols and phenoxyacids from aqueous samples.The possibility of using the BPA-MIP as a selective sorbent to preconcentrate these compounds from other samples such as urine and river water was also explored.

View Article: PubMed Central - PubMed

Affiliation: Institute of Natural Resources and Agrobiology (IRNASA-CSIC), 37008 Salamanca, Spain; E-Mail: eliseo.herrero@irnasa.csic.es.

ABSTRACT
A molecularly imprinted polymer (MIP), obtained by precipitation polymerisation with 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as cross-linker, and bisphenol-A (BPA) as template, was prepared. The binding site configuration of the BPA-MIP was examined using Scatchard analysis. Moreover, the behaviour of the BPA-MIP for the extraction of several phenolic compounds (bisphenol-A, bisphenol-F, 4-nitrophenol, 3-methyl-4-nitrophenol) and phenoxyacid herbicides such as 2,4-D, 2,4,5-T and 2,4,5-TP has been studied in organic and aqueous media in the presence of other pesticides in common use. It was possible to carry out the selective preconcentration of the target analytes from the organic medium with recoveries of higher than 70%. In an aqueous medium, hydrophobic interactions were found to exert a remarkably non-specific contribution to the overall binding process. Several parameters affecting the extraction efficiency of the BPA-MIP were evaluated to achieve the selective preconcentration of phenols and phenoxyacids from aqueous samples. The possibility of using the BPA-MIP as a selective sorbent to preconcentrate these compounds from other samples such as urine and river water was also explored.

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(a) Isotherms of the binding of BPA to the imprinted and non-imprinted polymers. Weight of polymer: 10 mg; volume of bisphenol-A standard solution in toluene: 1mL; binding time: 3 h; (b) Scatchard plot analysis of the binding of BPA to the imprinted polymer. Q is the amount of BPA bound to the MIP. [BPA]eq is the concentration of free bisphenol-A at equilibrium.
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f3-ijms-12-03322: (a) Isotherms of the binding of BPA to the imprinted and non-imprinted polymers. Weight of polymer: 10 mg; volume of bisphenol-A standard solution in toluene: 1mL; binding time: 3 h; (b) Scatchard plot analysis of the binding of BPA to the imprinted polymer. Q is the amount of BPA bound to the MIP. [BPA]eq is the concentration of free bisphenol-A at equilibrium.

Mentions: To estimate the binding affinity of the MIP for bisphenol-A in toluene, a saturation binding experiment and Scatchard analysis were carried out. The binding isotherms of bisphenol-A to the MIP and NIP were measured at several concentrations in the 0.01–2 mM range (Figure 3a). The amount of BPA bound to the MIP at binding equilibrium, Q, increased together with the increase in the initial concentration of BPA ([BPA]ini), and reached saturation at a higher concentration. On comparing the curves obtained for the MIP and the NIP, it may be seen that the amount of template bound to the imprinted polymer was much higher than that bound to the non-imprinted polymer. This suggests that the imprinted cavities of the MIP may be responsible for the high-affinity binding of the template to the polymer. The binding characteristics of MIPs can be estimated using Scatchard analysis. The Scatchard equation is:Q/[BPA]eq=(Qmax−Q)/KDwhere Q is the amount of bisphenol-A bound to the MIP at equilibrium; Qmax is the apparent maximum number of binding sites; [BPA] is the free BPA concentration at equilibrium, and KD is the equilibrium dissociation constant of the binding sites. Q/[BPA] was plotted vs. Q, as shown in Figure 3b. The Scatchard plot for the MIP is not a single linear curve: there are two distinct sections within the plot, with different slopes. This suggests that there are two classes of heterogeneous binding sites as regards affinity for bisphenol-A in the polymer. The linear regression equation for the left part of the curve in the figure is Q/[BPA]eq = −0.0975Q + 1.6786; the unit of Q is nmol. KD and Qmax were calculated to be 10.3 μmol L−1 and 17.3 μmol g−1 of dry polymer, respectively, from the slope and the intercept of the Scatchard plot. The linear regression equation for the right part of this curve is Q/[BPA]eq = −0.0016Q + 0.2806. KD and Qmax were calculated to be 625.0 μmol L−1 and 175.4 μmol g−1 of dry polymer.


Behavior of phenols and phenoxyacids on a bisphenol-A imprinted polymer. Application for selective solid-phase extraction from water and urine samples.

Herrero-Hernández E, Carabias-Martínez R, Rodríguez-Gonzalo E - Int J Mol Sci (2011)

(a) Isotherms of the binding of BPA to the imprinted and non-imprinted polymers. Weight of polymer: 10 mg; volume of bisphenol-A standard solution in toluene: 1mL; binding time: 3 h; (b) Scatchard plot analysis of the binding of BPA to the imprinted polymer. Q is the amount of BPA bound to the MIP. [BPA]eq is the concentration of free bisphenol-A at equilibrium.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3116193&req=5

f3-ijms-12-03322: (a) Isotherms of the binding of BPA to the imprinted and non-imprinted polymers. Weight of polymer: 10 mg; volume of bisphenol-A standard solution in toluene: 1mL; binding time: 3 h; (b) Scatchard plot analysis of the binding of BPA to the imprinted polymer. Q is the amount of BPA bound to the MIP. [BPA]eq is the concentration of free bisphenol-A at equilibrium.
Mentions: To estimate the binding affinity of the MIP for bisphenol-A in toluene, a saturation binding experiment and Scatchard analysis were carried out. The binding isotherms of bisphenol-A to the MIP and NIP were measured at several concentrations in the 0.01–2 mM range (Figure 3a). The amount of BPA bound to the MIP at binding equilibrium, Q, increased together with the increase in the initial concentration of BPA ([BPA]ini), and reached saturation at a higher concentration. On comparing the curves obtained for the MIP and the NIP, it may be seen that the amount of template bound to the imprinted polymer was much higher than that bound to the non-imprinted polymer. This suggests that the imprinted cavities of the MIP may be responsible for the high-affinity binding of the template to the polymer. The binding characteristics of MIPs can be estimated using Scatchard analysis. The Scatchard equation is:Q/[BPA]eq=(Qmax−Q)/KDwhere Q is the amount of bisphenol-A bound to the MIP at equilibrium; Qmax is the apparent maximum number of binding sites; [BPA] is the free BPA concentration at equilibrium, and KD is the equilibrium dissociation constant of the binding sites. Q/[BPA] was plotted vs. Q, as shown in Figure 3b. The Scatchard plot for the MIP is not a single linear curve: there are two distinct sections within the plot, with different slopes. This suggests that there are two classes of heterogeneous binding sites as regards affinity for bisphenol-A in the polymer. The linear regression equation for the left part of the curve in the figure is Q/[BPA]eq = −0.0975Q + 1.6786; the unit of Q is nmol. KD and Qmax were calculated to be 10.3 μmol L−1 and 17.3 μmol g−1 of dry polymer, respectively, from the slope and the intercept of the Scatchard plot. The linear regression equation for the right part of this curve is Q/[BPA]eq = −0.0016Q + 0.2806. KD and Qmax were calculated to be 625.0 μmol L−1 and 175.4 μmol g−1 of dry polymer.

Bottom Line: In an aqueous medium, hydrophobic interactions were found to exert a remarkably non-specific contribution to the overall binding process.Several parameters affecting the extraction efficiency of the BPA-MIP were evaluated to achieve the selective preconcentration of phenols and phenoxyacids from aqueous samples.The possibility of using the BPA-MIP as a selective sorbent to preconcentrate these compounds from other samples such as urine and river water was also explored.

View Article: PubMed Central - PubMed

Affiliation: Institute of Natural Resources and Agrobiology (IRNASA-CSIC), 37008 Salamanca, Spain; E-Mail: eliseo.herrero@irnasa.csic.es.

ABSTRACT
A molecularly imprinted polymer (MIP), obtained by precipitation polymerisation with 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as cross-linker, and bisphenol-A (BPA) as template, was prepared. The binding site configuration of the BPA-MIP was examined using Scatchard analysis. Moreover, the behaviour of the BPA-MIP for the extraction of several phenolic compounds (bisphenol-A, bisphenol-F, 4-nitrophenol, 3-methyl-4-nitrophenol) and phenoxyacid herbicides such as 2,4-D, 2,4,5-T and 2,4,5-TP has been studied in organic and aqueous media in the presence of other pesticides in common use. It was possible to carry out the selective preconcentration of the target analytes from the organic medium with recoveries of higher than 70%. In an aqueous medium, hydrophobic interactions were found to exert a remarkably non-specific contribution to the overall binding process. Several parameters affecting the extraction efficiency of the BPA-MIP were evaluated to achieve the selective preconcentration of phenols and phenoxyacids from aqueous samples. The possibility of using the BPA-MIP as a selective sorbent to preconcentrate these compounds from other samples such as urine and river water was also explored.

Show MeSH