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This month we interview Emanuela Gionfriddo, Assistant Professor of Chemistry at the Department of Chemistry and Biochemistry of the University of Toledo in Ohio, USA, about her work quantifying per- and polyfluoroalkyl (PFAS) in water using solid-phase microextraction liquid chromatography tandem mass spectrometry (SPME–LC–MS/MS) and the evolving field of sample preparation.
Q. When did you first encounter chromatography and what attracted you to the subject?
A: I encountered chromatography for the first time while working on my bachelor of science thesis at the University of Calabria in Italy. I was investigating the changes in the aroma profile of tomatoes based on their origin. The method involved the use of solid‑phase microextraction (SPME) coupled to gas chromatography–ion trap/mass spectrometry (GC–IT/MS). I was fascinated by the fact that these techniques allow to extract and separate so many chemicals and unveil the molecular composition of food aroma.
Q. Can you tell us more about your Ph.D. thesis?
A: My Ph.D. thesis focused on developing new derivatization methods for the analysis of challenging environmental contaminants such as hydrazine (1), food quality markers such as seleno amino acids (2), and neurotransmitters (3). Part of my thesis was also focused on the fundamental understanding of sorption mechanisms and displacement phenomena on solid SPME sorbents (4).
Q. What chromatographic techniques have you worked with?
A: I have worked with one-dimensional and two-dimensional gas chromatography coupled to mass spectrometry. In my laboratory, we are also working with high and ultrahigh-performance
liquid chromatography (HPLC and UHPLC).
Q. You recently published a paper detailing how to minimize the effects of transient microenvironments (TME) by hyphenating for the first time SPME Arrow to MS via thermal desorption (TD) and direct analysis in real time (DART). What is novel about this approach and what does it offer over other methods?
A: This methodology involves heated enclosed desorption of Arrow SPME for DART-MS analysis. This approach allows to confine the SPME desorption and analytes’ ionization region, providing a more efficient introduction of the analytes into the MS system (5). This, in turn, helps to minimize interferences and background noise generated by the surrounding environment, with a significant potential to expand the use of this technology for on-site analysis. Compared to other approaches, this method allows for more precise interday measurements by DART-MS and for an easy and consistent introduction of Arrow SPME devices into the desorption chamber.
Q. What challenges did you encounter when combining these two technologies and how did you overcome them?
A: The main challenge for this work was to create a system that would allow for reproducible sample introduction and would maximize the desorption efficiency while improving ion transmission to the MS system. We overcame these challenges by modifying the design of a thermal desorption unit used for DART-MS and by studying which sorbent thickness/length would provide the sharpest desorption profiles with optimum signal‑to‑noise ratio (S/N).
Q. You have also used SPME–liquid chromatography (LC)–MS/MS to quantify per- and polyfluoroalkyl (PFAS) in water. Could you talk a little about this work?
A: This work used a hydrophilic-lipophilic balance weak anion exchange (HLB-wax) sorbent immobilized on SPME devices for the selective extraction of PFAS from various environmental samples. The SPME extracts were injected in a ultrahigh-performance liquid chromatography-laminar flow tandem mass spectrometry system. Analysis of PFAS is extremely challenging due to potential contamination at all stages of analysis, which can result in false-positive results, especially at the low concentrations (part per trillion) at which these analytes are usually detected in environmental samples. The main issue is that contamination sources in the laboratory are not well characterized and can arise from the use of many laboratory products, including sample preparation supplies. For this reason, it is important to minimize sample handling and the various stages needed for extraction: SPME can achieve this. In fact, the protocol developed by my group not only establishes SPME as a reliable preconcentration method for the ultratrace analysis of PFAS in aqueous matrices but also lays the groundwork for future studies involving the analysis of PFAS in more complex samples (6).
Q. What is novel about this research?
A: In this work we assessed that SPME can be considered an alternative sample preparation strategy to existing methods for the analysis of PFAS, such as dilute-and-shoot performed in accredited methods by the U.S. EPA. We also investigated how the selectivity of the extraction process is dependent not only on hydrophobic interactions but also on anion exchange mechanisms. Moreover, we assessed matrix effects for these analytes in various environmental samples.
Q. What projects are you working on next?
A: I certainly want to continue working on PFAS research for analysis of more complex samples by expanding the range of PFAS simultaneously analyzed and pushing down the limits of detection achievable with the preconcentration ability of SPME devices. We are also working on the development of new extraction phases obtained from low-cost and renewable materials for extraction of environmental toxins.
Q. What are the emerging trends in sample preparation?
A: The field of sample preparation has been developing at an exponential rate in the past 10 to 15 years. And I am glad to see that this field is gaining more attention and respect in the separation science community. Certainly, emerging trends include “greening” sample preparation as much as possible, providing streamlined protocols compatible with automation. Several research groups are expanding the capability of extraction technologies, such as microextraction, to in vivo methods, and also to the analysis of metals and nucleic acids, which is paving the way to a very broad range of innovative applications.
Recent trends also involve developing sample preparation solutions that include a completely green cycle: starting from a green sorbent synthesis to minimization of waste produced during the extraction procedure.
Q. How do you see the role of the next generation of academic separation scientists in modernizing the strategies for teaching separation science? What particular challenges are facing you?
A: Separation science research is evolving at a very fast speed; however, separation science education can’t always catch up with modern trends in the field. The separation science community is currently making efforts to bring innovative strategies into the classroom and raise awareness on the importance that separation processes have in our everyday life. In this way we can motivate the next generation of scientists to explore degrees and careers in this field. One of the main challenges I am facing is to make my students understand that chromatographic systems are not “black boxes”, and that to control what happens in a chromatographic column we need to understand the chemistry of the interactions between molecules and the stationary phase. Only in this way can we fully control the chromatographic process and tune it to fulfill our analytical needs. I am also trying to integrate into my class curriculum alternative topics in separation science, such as extraction technologies, and provide the students with hands-on experience that I am sure will be extremely useful for their future careers.
Q. What advice would you give to someone who is thinking of going into separation science teaching?
A: Be creative and strive to link your educational content with topics of broad interest for your students. Explore new ways to let your students acquire hands-on experience in separation processes in the laboratory, even when chromatographic equipment is not readily available. Many interesting strategies have been proposed in the literature that can be easily implemented in the teaching laboratories nowadays.
Last but not least, strive to link all the separation processes to the fundamental interactions of molecules with stationary or extraction phases, to teach students the chemistry behind separation science.
Emanuela Gionfriddo is an Assistant Professor of Chemistry at the Department of Chemistry and Biochemistry of The University of Toledo in Ohio, USA. Research work in Dr. Gionfriddo’s laboratory focuses on the development of advanced analytical separation tools for the analysis of complex biological and environmental matrices, with an emphasis on alternative green sample preparation methodologies. She received her B.Sc. (2008) and M.Sc. (2010) in chemistry and her Ph.D. in analytical chemistry (2013) at the University of Calabria (Italy). She joined Professor Pawliszyn’s group at the University of Waterloo (Ontario, Canada) in 2014 as postdoctoral fellow and manager of the gas chromatography section of the Industrially Focused Analytical Research Laboratory (InFAReL), and within three years became a research associate. She has currently authored over 50 peer-reviewed contributions including a patent on PTFE‑based SPME coatings. Dr. Gionfriddo is one of the founding members of the Dr. Nina McClelland Laboratory for Water Chemistry and Environmental Analysis at The University of Toledo and she is appointed to the Ohio Attorney General Yost’s Environmental Council of Advisors. She also serves on the executive committee of the American Chemical Society Analytical Division Subdivision on Chromatography and Separations Chemistry. Her research programme is currently funded by the National Oceanic and Atmospheric Administration and several industrial partnerships.
Rising Stars of Separation Science The Column, will be running a series of interviews in 2021, featuring the next generation of separation scientists. If you would like to nominate a “rising star” for consideration, please send the name of the candidate and why they deserve recognition to Alasdair Matheson, Editor-in-Chief, LCGC Europe at firstname.lastname@example.org