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## Molecularly imprinted polymers and hybrid materials for determination of chemical compounds in mass spectrometry

### Maria Guć

#### Abstract

The series of publications presents new materials that allow the isolation of an analyte from samples with a complex chemical composition, and the enrichment of a test substance in MIPs/mag-MIPs structures from highly diluted solutions. Polymers with a molecular imprint, selective for the following compounds were obtained: flavonoids – quercetin; female sex hormones – estrone and β-estradiol; non-steroidal inflammatory drugs – naproxen, diclofenac, and ibuprofen; herbicides – 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) and flavonoid glycosides – rutin. For selected MIPs, magnetic analogs were synthesized by the core-shell method. The magnetic core consisted of Fe3O4 nanoparticles, coated with a polymer obtained by the same synthesis as MIPs. Magnetic polymers with molecular recognition for quercetin, estrone, β-estradiol, and the cyanogenic glycoside – amygdalin were obtained. The use of a magnetic core allowed for the fast and efficient magnetic separation process of mag-MIPs from solutions with neodymium magnet (few seconds). In addition, the use of spherical Fe3O4 nanoparticles as a magnetic core surrounded by a polymer coating of mag-MIPs resulted in the location of specific recognition sites in the outer layer of the material, rendering them more accessible during the analyte binding, thus increasing the efficiency of mag-MIPs in comparison to MIPs. MIPs and mag-MIPs were used for the analysis of chemical compounds by the two techniques ESI-MS and FAPA-MS. In classical ESI-MS analysis, MIPs/mag-MIPs are introduced into the sample solution, where the analyte is bound in the polymer structure. The polymer and bound analyte are then removed from the sample, washed, and placed in a small volume of clean solvent where the analyte is released. The analyte solution prepared in this way is quantitatively and qualitatively analyzed using soft ionization ESI-MS. The proposed method of the analyte preconcentration using MIPs/mag-MIPs combined with ESI-MS made it possible to significantly reduce the limit of detection for the majority of tested organic compounds and to eliminate the influence of interferents on the analysis result. Despite the use of the soft ionization method in the ESI-MS, m/z signals are observed not only from the analyte itself [M + H]+, [M - H]-, but also from sodium adducts, dimers, and fragmentation products, which may significantly affect the use of this method for the quantitative analysis of selected analytes. In the FAPA-MS method, MIPs/mag-MIPs are introduced into the sample, where the analyte is bound in the polymer structure. The MIPs/mag-MIPs along with the bound analyte are then isolated from the solution, washed, and analyzed directly from the polymer structure by FAPA-MS. The thermally released analyte is ionized with low-temperature plasma under atmospheric pressure and, together with the carrier gas, transported to the mass spectrometer, where the ions are analyzed. This approach not only shortens the time and simplifies the analysis protocol, but in many cases significantly lowers the limit of detection of low-molecular-weight organic compounds, solves the problem of fragmentation, dimers formation, sodium ions adducts, complex formation, and solvent interactions. This method allowed to develop a methodology for quantifying quercetin. Moreover, the lower consumption of solvents makes the proposed method environmentally friendly and compliant with the principles of Green Chemistry, which was demonstrated by the analysis of non-steroidal anti-inflammatory drugs. For estrogen analysis, we proposed a protocol for the selective quantitative analysis of estrone and β-estradiol. Additionally, the obtained MIPs and mag-MIPs allow for the stable "storage" of hormones bound in the polymer structure for 72 hours, which is crucial in the case of the environmental samples’ analysis, where the time from collection to analysis is longer than the time of hormone decomposition. A protocol for the determination of amygdalin has also been proposed. The method was evaluated using a certified reference material – apricot kernels. Moreover, various types of plasma generation sources were tested in the FAPA-MS technique. In the last stage of the research, it was shown that the polymer structure itself does not adversely affect living organisms, therefore MIPs/mag-MIPs can be used in environmental samples. Toxicity tests were carried out on two types of organisms: Daphnia magna Straus and Tetradesmus obliquus (Turpin) M.J. Wynne. It was proved that the initial assumptions were correct and the combination of the technology of producing polymers with a molecular imprint with the method of direct FAPA-MS analysis with plasma ionization solves many complex analytical problems. The proposed methods can be successfully used in the pharmaceutical industry for the determination of active substances in drugs or their residues, e.g. in sewage, in the medical industry, for example, for the determination of substances in the blood, in sport for the determination of prohibited substances from urine or blood, in the cosmetics industry for analysis substrates, products, or wastewater, and the protection of the environment.
Record ID
UAMdebcfe1ca27b4c16ac527273e7e56c73
Diploma type
Doctor of Philosophy
Author
Title in Polish
Polimery z odciskiem molekularnym oraz układy hybrydowe do oznaczania związków chemicznych z zastosowaniem spektrometrii mas
Title in English
Molecularly imprinted polymers and hybrid materials for determination of chemical compounds in mass spectrometry
Language
• eng (en) English
• pol (pl) Polish
Certifying Unit
Wydział Chemii [nowa struktura organizacyjna] (SNŚ/WC)
Scientific discipline (2.0)
6.5 chemical sciences
Year of creation
2021
Start date
2020
Defense Date
29-05-2021
Title date
29-05-2021
Supervisor
URL
https://hdl.handle.net/10593/26317 Opening in a new tab
Keywords in English
mag-MIP; FAPA-MS; MIP; ESI-MS; trace analysis
Abstract in English
The series of publications presents new materials that allow the isolation of an analyte from samples with a complex chemical composition, and the enrichment of a test substance in MIPs/mag-MIPs structures from highly diluted solutions. Polymers with a molecular imprint, selective for the following compounds were obtained: flavonoids – quercetin; female sex hormones – estrone and β-estradiol; non-steroidal inflammatory drugs – naproxen, diclofenac, and ibuprofen; herbicides – 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) and flavonoid glycosides – rutin. For selected MIPs, magnetic analogs were synthesized by the core-shell method. The magnetic core consisted of Fe3O4 nanoparticles, coated with a polymer obtained by the same synthesis as MIPs. Magnetic polymers with molecular recognition for quercetin, estrone, β-estradiol, and the cyanogenic glycoside – amygdalin were obtained. The use of a magnetic core allowed for the fast and efficient magnetic separation process of mag-MIPs from solutions with neodymium magnet (few seconds). In addition, the use of spherical Fe3O4 nanoparticles as a magnetic core surrounded by a polymer coating of mag-MIPs resulted in the location of specific recognition sites in the outer layer of the material, rendering them more accessible during the analyte binding, thus increasing the efficiency of mag-MIPs in comparison to MIPs. MIPs and mag-MIPs were used for the analysis of chemical compounds by the two techniques ESI-MS and FAPA-MS. In classical ESI-MS analysis, MIPs/mag-MIPs are introduced into the sample solution, where the analyte is bound in the polymer structure. The polymer and bound analyte are then removed from the sample, washed, and placed in a small volume of clean solvent where the analyte is released. The analyte solution prepared in this way is quantitatively and qualitatively analyzed using soft ionization ESI-MS. The proposed method of the analyte preconcentration using MIPs/mag-MIPs combined with ESI-MS made it possible to significantly reduce the limit of detection for the majority of tested organic compounds and to eliminate the influence of interferents on the analysis result. Despite the use of the soft ionization method in the ESI-MS, m/z signals are observed not only from the analyte itself [M + H]+, [M - H]-, but also from sodium adducts, dimers, and fragmentation products, which may significantly affect the use of this method for the quantitative analysis of selected analytes. In the FAPA-MS method, MIPs/mag-MIPs are introduced into the sample, where the analyte is bound in the polymer structure. The MIPs/mag-MIPs along with the bound analyte are then isolated from the solution, washed, and analyzed directly from the polymer structure by FAPA-MS. The thermally released analyte is ionized with low-temperature plasma under atmospheric pressure and, together with the carrier gas, transported to the mass spectrometer, where the ions are analyzed. This approach not only shortens the time and simplifies the analysis protocol, but in many cases significantly lowers the limit of detection of low-molecular-weight organic compounds, solves the problem of fragmentation, dimers formation, sodium ions adducts, complex formation, and solvent interactions. This method allowed to develop a methodology for quantifying quercetin. Moreover, the lower consumption of solvents makes the proposed method environmentally friendly and compliant with the principles of Green Chemistry, which was demonstrated by the analysis of non-steroidal anti-inflammatory drugs. For estrogen analysis, we proposed a protocol for the selective quantitative analysis of estrone and β-estradiol. Additionally, the obtained MIPs and mag-MIPs allow for the stable "storage" of hormones bound in the polymer structure for 72 hours, which is crucial in the case of the environmental samples’ analysis, where the time from collection to analysis is longer than the time of hormone decomposition. A protocol for the determination of amygdalin has also been proposed. The method was evaluated using a certified reference material – apricot kernels. Moreover, various types of plasma generation sources were tested in the FAPA-MS technique. In the last stage of the research, it was shown that the polymer structure itself does not adversely affect living organisms, therefore MIPs/mag-MIPs can be used in environmental samples. Toxicity tests were carried out on two types of organisms: Daphnia magna Straus and Tetradesmus obliquus (Turpin) M.J. Wynne. It was proved that the initial assumptions were correct and the combination of the technology of producing polymers with a molecular imprint with the method of direct FAPA-MS analysis with plasma ionization solves many complex analytical problems. The proposed methods can be successfully used in the pharmaceutical industry for the determination of active substances in drugs or their residues, e.g. in sewage, in the medical industry, for example, for the determination of substances in the blood, in sport for the determination of prohibited substances from urine or blood, in the cosmetics industry for analysis substrates, products, or wastewater, and the protection of the environment.

Uniform Resource Identifier
https://researchportal.amu.edu.pl/info/phd/UAMdebcfe1ca27b4c16ac527273e7e56c73/
URN
urn:amu-prod:UAMdebcfe1ca27b4c16ac527273e7e56c73

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