Title : Use of molecularly imprinted polymers (MIPs) and magnetic molecularly imprinted polymers (mag-MIPs) in flowing atmospheric-pressure afterglow mass spectrometry (FAPA-MS)
Abstract:
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), flavonoid glycosides – rutin and cyanogenic glycoside – amygdalin. 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. 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 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 and analyzed directly from the polymer structure. 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. Different types of plasma torches were tested (V-FAPA, L-FAPA). Moreover, the lower consumption of solvents makes the proposed method environmentally friendly and compliant with the principles of Green Chemistry. A protocol combining the use of MIPs/mag-MIPs with FAPA-MS analysis was successfully applied to the analysis of real samples.
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.
Audience take-away:
- Methods of obtaining selective Molecularly Imprinted Polymers (MIPs) and their magnetic analogs (mag-MIPs) for the isolation and pre-concentration of analytes will be presented.
- The direct Flowing Atmospheric-Pressure Afterglow Mass Spectrometry (FAPA-MS) analysis of bound small organic compounds from MIPs/mag-MIPs structures will be presented. It is a new analytical technique using low-temperature plasma ionization that allows qualitative and quantitative analysis of a compound from a solid phase.
- Various types: V-shaped and L-shaped plasma torches will be presented.
- Analytical parameters for the technique combining the use of MIPs/mag-MIPs and the ESI-MS and the new technique using MIPs/mag-MIPs in FAPA-MS analysis will be compared. The results obtained for the analysis of environmental samples will be presented.
- Discussion of the toxicity of the obtained polymeric materials on organisms, while using them for the analysis of environmental samples, e.g. water from rivers, lakes.
