Ahuja Award Session Demonstrates the Significance of Analytical Extraction Techniques

Prof. Emanuela Gionfriddo of the University of Toledo, in Ohio, is the recipient of the ACS Analytical Division 2023 Satinder Ahuja Award for Young Investigators in Separation Science, which was presented to her at Pittcon 2023. The purpose of this award is to recognize and encourage outstanding contributions to the fields of analytical chemistry by a young analytical scientist based on or more of the following criteria: conceptualization and development of unique instrumentation for separations; development of novel and important separation methods or methodologies; elucidation of theory or fundamental processes involved in separations; and other significant contributions to the furtherance of separation science role in the use of chemical instrumentation.

Gionfriddo: Microextractions to Separate Complex, Heterogenous Mixtures

A 2023 double winner, Gionfriddo also received the 2023 LCGC Emerging Leader in Chromatography Award, which was presented in another Pittcon 2023 session. Her Young Investigator award presentation, entitled “Unraveling the Composition of Heterogenous Systems One Microextraction at a Time,” covered a variety of topics including her giving thanks to her mentors along the way in her early career. Gionfriddo’s academic emphasis on sample preparation of small molecules in complex samples poses the ultimate challenge to any analytical method development process, whether for targeted- or non-targeted analysis. She has seen a shift toward greener and faster approaches, guaranteeing sustainability and high throughput of the extraction process. Her work in the area of solid-phase microextraction (SPME) complies with all of those features and also provides simultaneous extraction and enrichment of the targeted analytes. One of her contributions in this area has been the study of mass transfer of small metabolites into solid SPME sorbents to study competitive adsorption phenomena with important implications to food and beverage analysis. Using biocompatible extraction phases, her research group did validation studies of SPME methods for extraction of small molecules from environmental samples. They also looked at various sorbents for SPME methods for enhanced extraction of polar analytes.

Anderson: Advancing the Analysis of Nucleic Acids with Ionic Liquids

Prof. Jared Anderson of Iowa State University is an expert in the area of sample preparation for chromatography and spectroscopy and his research group has contributed heavily in this area. His latest focus has been on ionic liquids (ILs), magnetic ionic liquids (MILs), and polymeric ionic liquids (PILs) that exhibit unique properties in analytical and bioanalytical applications. His talk focused on the use of these ionic liquids in the analysis of nucleic acids. Nucleic acids are biopolymers that constitute important diagnostic molecules for a broad range of applications from clinical testing to forensic analysis. A major challenge faced by DNA and RNA analysis techniques is the selective extraction of particular nucleic acid sequences using rapid and sensitive methodologies.

In this presentation, Anderson showed that ion-tagged oligonucleotides (ITOs) can be used in conjunction with MILs to efficiently capture DNA sequences from complex samples. The ITOs can be created through thio-lene “click” chemistry and the nature of the ion tag can influence the partitioning of the ITO to the hydrophobic MIL. This novel liquid-phase approach toward sequence-selective DNA capture provides superior extraction efficiencies to conventional magnetic-bead technology as well as a platform for using external fields to manipulate the liquid droplets. The Anderson group’s work on MILs represents the first example of liquid-phase nucleic acid extraction solvents and shows great promise to become a standard technique in this difficult extraction area. The MILs used in this extraction technique allow tuning through their design and synthesis. The ILs and MILs can be employed for the rapid uptake of DNA from the surface of plants for downstream qPCR analysis.

The development of isothermal amplification approaches capable of achieving single-nucleotide resolution of nucleic acid sequences was also demonstrated through the use of molecular beacons. Molecular beacons can enable specific detection of loop mediated isothermal amplification (LAMP) on lateral-flow strips. This technique is faster than qPCR with equal or better sensitivity.

Some of the other areas that Anderson touched was work that his group is doing on point-of-care diagnostics using a molecular PCR system as well as using MIL-based liquids to lyse cells and extract DNA directly from blood and plasma.

Olesik: Ordered Carbon Materials for Selective Preconcentration

Prof. Susan Olesik of The Ohio State University presented a lecture entitled “Ordered Carbon Materials for Selective Preconcentration.” She and her research group have been focusing on the use of carbon nanomaterials (nanoparticles and nanofibers) for applications in sample preparation. In the work presented in talk, Olesik and her research group studied ordered carbon materials for selective preconcentration using solid-phase microextraction (SPME) or solid-phase extraction (SPE) of polar and moderately polar compounds that are commonly separated by liquid chromatography.

These carbon materials have a high surface area and homogenous particle sizes or fiber diameters. Chemically and physically carbon is a robust adsorbent that sometimes has too much retention. It can attract both positive and negative compounds. For carbon nanofibers, one starts with commonly used SU-8 epoxy-based negative photoresist polymer. When exposed to UV light, polymerization occurs and the resulting polymer can be electrospun into various dimensions of nanofibers. These products can furthermore be imprinted with molecular templates that can be removed, leaving behind a molecularly imprinted polymer that can withstand high temperatures without losing the template shape. In addition, the imprints remain for a long time. Greater adsorption was observed for the imprinted molecules compared to other molecules in a mixture of compounds. For example, in an analysis of beer, she showed that their fibers that were imprinted for small sulfur compounds preferentially adsorbed sulfur compounds as opposed to other common compounds that are found in beer.

Kirchhoff: Using Conducting Polymer Sorbents to Improve Extractions

Conducting polymers are versatile materials used for a wide range of analytical applications. Common conducting polymers are derived from simple heterocycles such as pyrrole and thiophene, which can be further functionalized to create new materials with unique properties for inclusion in separation methods and electroanalysis. In the first part of this presentation, by Prof. Jon Kirchoff of the University of Toledo, in Ohio, the incorporation of versatile chelating agents in a conducting polymer coating for solid-phase microextraction (SPME) of metals was discussed. The second part of the presentation focused on a new class of N-functionalized pyrrole monomers, pyrrole-1-carbodithioic acid and pyrrole-1-carboxylic acid, that when polymerized yield air-stable, granular materials that are insoluble and highly dispersible in aqueous solution. Chemical or electrochemical polymerization of the functionalized monomers introduce coordinating groups throughout the polymer structure as permanent sites for the extraction of a wide range of metals. Numerous stand-alone sorbent materials have been developed for dispersive solid-phase extraction (DSPE) of metals including precious metals, heavy metals, and rare earth elements.

Kirchoff also discussed a new environmental friendly sorbent based on caffeic acid for the extraction of rare earth elements. Removal and recovery efficiencies are metal- and sorbent-dependent, but in many cases efficiencies greater than 90% are readily achieved with the ability to detect individual metals at the ng/L level.

Pawliszyn: The Significance of Fundamentals in the Development and Optimization of Extraction

Winding up the Young Investigator Award session, Prof. Janusz Pawliszyn of the Univ. of Waterloo, Ontario, who is well known as a sample preparation expert, gave the final lecture. Like many practitioners, he believes that sample preparation is a critical step in the analytical process. However, approaches to optimizing the associated parameters are often based on trial and error rather than rational scientific methodologies. If an extraction method provides good recovery, it is assumed that it works well and no further consideration is given to the underlying principles driving its performance. Such a perspective suggests that when it comes to sample preparation, the fundamentals of method optimization are not as important as in other technologies, such as chromatography or mass spectrometry. This is the main reason why the fundamentals of sample preparation are not typically covered in analytical chemistry curricula. Throughout his scientific career, Pawliszyn has carefully considered the underlying principles of sample-preparation procedures, and this work has led to his development of a range of extraction technologies, most notably solid-phase microextraction (SPME). that have been put to practical use in many laboratories around the world.

Special attention was given in Pawliszyn’s presentation to the potential benefits of using SPME, such as higher enrichment and better performance in the characterization of complex systems, including in vivo investigations. Furthermore, optimal approaches to addressing challenges such as swelling and saturation effects were also discussed, because such issues can impair accurate quantification. The information about the operational details of SPME that were provided will not only be critical to facilitating its continued evolution, but it will also be helpful for both SPME users and other scientists interested in gaining greater insight into extraction principles more generally.

Pawliszyn also thanked Gionfriddo for the excellent work she carried out in his laboratory at the University of Waterloo, first as a postdoctoral fellow and later as a research associate. He acknowledged that he was extremely demanding and put her through a lot, jokingly illustrating this with a picture of Gionfriddo in front of a sign for the town of Hel, Poland, from a trip that the research group took to Pawliszyn’s native land.