Grow Your Skills in the Budding Cannabis Industry 

Analysis of Size-Based Heterogeneities in Monoclonal Antibody–Based Biotherapeutic Products

Two-Dimensional Liquid Chromatography (2D-LC)

A Look at Asymmetrical Flow Field-Flow Fractionation

Analysis of Proteins, Biologics, and Nanoparticles in Biological Fluids 

Critical Evaluation of Chromatography Methods—Essential Detective Skills

How Switching from Helium to Hydrogen Carrier Gas in Thermal Desorbers Enhances GC–MS Systems

A Look at Mainstream Smoke of Heat-Not-Burn Tobacco Product for HPLC Analysis

Acid-Catalyzed Isomerization of Carbonyls-2,4-dinitrophenylhydrazone 

An undeniable effect of the COVID-19 pandemic is that we have learned how to adapt (quickly) to sudden changes.

This blog is a collaboration between LCGC and the American Chemical Society Analytical Division Subdivision on Chromatography and Separations Chemistry.

The educational services sector, in particular, had to develop new learning strategies that could replace in-person learning. Instructors also faced the challenge of having to suddenly teach and assess students’ learning in ways that were not the norm.

Mentorship has also drastically changed in academia, and I believe in other sectors as well.

Because of social distancing, the in-person mentoring experience was abruptly interrupted, and many mentees suddenly had to adapt to interacting with their mentors through a screen and a microphone. “Zoom fatigue,” a different meeting environment, “can you hear me?” “you are breaking up,” “my camera doesn’t work,” “how do I share my presentation?” are all new issues (and distractions) that have become part of mentor–mentee interactions. And even when in-person meetings are possible, mask-wearing has impacted mentors’ ability to gauge mentorship connections. It is much harder to read people’s emotions and to anticipate if there is stress, anxiety, nervousness, confusion, frustration, and so on, or later assess the level of each mentee’s enthusiasm and motivation.

The informal drop-in time in laboratories and occasional chats in the laboratory are sorely missed in most cases by both mentors and students, and often online meetings bring a detrimental sense of formality to the mentoring relationships since all meetings need to be on a “schedule.”

However, learning how to communicate through online meetings has also allowed us to explore many new mentorship opportunities we hadn’t thought of before and has made networking with people in different places and across time zones even easier.

: This fantastic program provides mentorship for economically disadvantaged high school students by enhancing their research experience and facilitating their entry to higher education in science, technology, engineering, and math (STEM) fields. Before COVID-19, the program was exclusively in-person. Now, virtual projects are also available for students that are not situated in proximity to a Project SEED site!

In addition, other existing programs that enabled remote learning and support for an enhanced mentorship experience have gained attention and expanded their reach even more since the pandemic hit. This expansion has allowed so many mentors to engage their mentees during the difficult times of remote learning. In this context, I want to mention a very interesting program at The University of Toledo (my academic home) called S.C.O.P.E (

Scientists Changing Our Pre-College Education

). This program provides high-school teachers with resources that enhance the quality of the STEM educational curricula and exposes students to various scientific methods with a hands-on approach. Since the start of the COVID-19 pandemic, the program has enabled students not only to gain a unique remote learning experience but also access to advanced instrumentation such as scanning electron microscopes, confocal fluorescent light microscopes, and gas chromatography–mass spectrometry instruments. Initially, the program mainly focused on communities surrounding Toledo (Ohio); however, in 2020 and 2021 it has expanded to 15 U.S. states! Best of all, the program is absolutely free to any high school wishing to participate!

For education in the chemical sciences, an additional challenge was to reinvent and convert chemistry laboratories for remote learning. For analytical chemistry laboratories that rely on wet chemical methods and specialized equipment, this switch was not an easy task.

However, this challenge brought many innovative strategies to teaching experimental analytical chemistry. Let’s have a look at a few examples:

Paper-based analytical devices (PAD) were designed for remote learning environments to achieve simple quantitative colorimetry without micropipettes: This approach allows instructors to choose any colorimetric reaction to be used with a proposed PAD format and to perform quantitative measurements based on images taken with smartphones or digital cameras (1).

The Making Introductory Courses Real while Online (MICRO) laboratory project was developed to meet the need for analytical chemistry hands-on experiments to be delivered remotely or in a socially distanced in-person laboratory. The team has developed seven publicly available, inquiry-based experiments that use paper microfluidic devices. Small quantities of reagents can be safely embedded in paper, similar to pH paper or aquarium test strips, and sent through the mail to students (2).

A method for at-home analysis of food dyes was developed to train students on basic concepts of analytical method development and calibration using a smart phone as a detector, and kitchen tools for sample preparation. This guided inquiry approach to learning is based on resources each student has available at home and thus requires inductive or discovery learning. In this way, the instructor serves as facilitator of student learning rather than disseminator (3).

In addition to the educational mentoring strategies described above, the scientific community has also found interesting ways to get together despite many conference cancellations. New enthusiastic groups were formed that provided online events to mitigate the feeling of isolation that many inevitably have had to embrace. Within the analytical chemistry realm, I want to mention Females in Mass Spectrometry (FeMS), which has done a spectacular job in forming a community that brings many scientists together with a series of engaging online events and mentorship programs. FeMS has really made a difference for so many scientists not only in the United States but all around the world.

Currently, I am fortunate to work with an amazing team in the ACS Analytical Subdivision for Chromatography and Separation Chemistry, and we look forward to providing service to our community and new mentorship opportunities for junior chromatographers and separation chemists.

I want to take this opportunity to share some events we are planning:

: We want to provide the graduating class of undergraduate and graduate students in chromatography and separation chemistry with an opportunity to get noticed by potential employers in industry and academia. Are you a student and would like to participate? Are you a mentor and have a student that can benefit from this opportunity? Fill out the 

Virtual poster presentations from graduate and undergraduate students:

 Let’s bring together our community and get to know each other! Are you interested? Fill out this 

Virtual discussions with editors of separation journals

 for tips on successful manuscript submissions.

Virtual discussions on the role of separations chemists in industrial development and innovation

 and engagement with industrial leaders to explore job opportunities for separation chemists.

Stay tuned for more information about these events that will be announced on the ACS SCSC website (

acsanalytical.org/subdivisions/separations/

), on our LinkedIn page (ACS SCSC (Subdivision of Chromatography & Separations Chemistry) and on Twitter (@AcsScsc).

And if you are looking for a mentor in the field of chemistry, don’t forget to check out all the opportunities that the American Chemical Society provides! (For more info click 

T. Komatsu, R.R. Gabatino, H. Hofileña, M. Maeki, A. Ishida, H. Tani, and M. Tokeshi, 

https://doi.org/10.1021/acs.jchemed.1c00100

R.M. Roller, S. Sumantakul, M. Tran, A. Van Wyk, J. Zinna, D.A. Donelson, S.G. Finnegan, G. Foley,O.R. Frechette, J. Gaetgens, J.Jiang, K.C. Rinaolo, R.S. Cole, M. Lieberman, V.T. Remcho, and K.A. Frederick, 

https://doi.org/10.1021/acs.jchemed.1c00214

https://doi.org/10.1021/acs.jchemed.0c00604

Emanuela Gionfriddo is an Assistant Professor of Chemistry in the Department of Chemistry and Biochemistry of The University of Toledo (Ohio). Research work in the Gionfriddo laboratory focuses on the development of advanced analytical separation tools for the analysis of complex biological and environmental matrices, with emphasis on alternative green sample preparation methodologies. Prof. Gionfriddo 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 Prof. Janusz Pawliszyn’s group at the University of Waterloo (Ontario, Canada) in 2014 as a post-doctoral 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 authored more than 50 peer-reviewed contributions including a patent on PTFE-based SPME coatings. She 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 an appointed member of the Ohio Attorney General Yost’s Environmental Council of Advisors. She also serves on the executive committee of the ACS Subdivision on Chromatography and Separations Chemistry. Her research program is currently funded by the National Oceanic and Atmospheric Administration and several industrial partnerships.

 and the American Chemical Society Analytical Division Subdivision on Chromatography and Separations Chemistry (ACS AD SCSC). The goals of the subdivision include

promoting chromatography and separations chemistry

organizing and sponsoring symposia on topics of interest to separations chemists

developing activities to promote the growth of separations science

increasing the professional status and the contacts between separations scientists.

For more information about the subdivision, or to get involved, please visit 

https://acsanalytical.org/subdivisions/separations/

Articles

An undeniable effect of the COVID-19 pandemic is that we have learned how to adapt (quickly) to sudden changes. 

The LCGC Blog: Mentorship in the Time of COVID-19: Finding the Silver Lining and Announcing ACS SCSC Initiatives 

The presence of per- and polyfluoroalkyl substances (PFAS) in products used every day by millions of people is a cause of concern among both consumers and scientists. PFAS found in drinking water and the environment can cause serious health issues in animals and humans. Amanda Belunis, who is a PhD candidate at the University of Maryland in Baltimore County, has been investigating the use of liquid chromatography­­–tandem mass spectrometry (LC–MS/MS) to detect PFAS from a variety of environmental sources. She spoke with us about methods used to detect PFAS and described a new method that she and her team have developed to enhance PFAS detection.

What are per and polyfluoroalkyl substances (PFAS) and how do they enter and contaminate consumer products?

Per and polyfluoroalkyl substances (PFAS) are a large family of manmade fluorinated chemicals that were developed in the 1940s. PFAS consist of a fully (per) or partially (poly) fluorinated chain connected to various functional groups. The compounds are hydrophobic, lipophilic, thermally stable, and generally inert and nonreactive, properties that are beneficial for a wide variety of applications including but not limited to non-stick cookware, food packaging, stain repellants, and aqueous film forming foam (AFFF) used by firefighters. The main way PFAS can be present in consumer products is through direct means (for example, non-stick cookware and water-repellant clothing). PFAS can also contaminate consumer products such as drinking water through indirect means such as stormwater runoff or waste from nearby industrial facilities.

You recently presented a technical poster that spotlighted an improved method validation and application for the detection of PFAS in drinking water sources following Environmental Protection Agency (EPA) 537.1 (1). How does this method differ from previous methods? What are its advantages?

This method provides further validation of EPA 537.1 on commercial instrumentation. I think one of the advantages this developed method offers is the various implementations made to reduce potential contamination. Additionally, along with collaborators at PerkinElmer, we were able to develop a higher throughput method by making changes to the liquid chromatography parameters, cutting down the run time from the recommended 37 min to 10 min.

What challenges did you face in developing your method? How were they resolved?

PFAS are ubiquitous in the environment, including the laboratory, as these compounds are commonly used in many products including materials used for an SPE setup and LC–MS systems. In developing our method, we noted that there were several compounds present in blanks. The first step to resolving this issue was the installation of a secondary column between the pump and the autosampler, deemed the 

. A delay column helps to remediate any PFAS that may be innately present in the eluents used for the HPLC pump, by delaying the elution of background PFAS. Following the installation, background contamination was not completely resolved. This led to further steps being taken, including modifications to both the SPE apparatus and the autosampler to remove any polytetrafluoroethylene (PTFE) or PTFE copolymers. Contamination arising from the autosampler was remediated by switching PTFE tubing for polyetheretherketone (PEEK) material. Through method development and troubleshooting, I have learned that one of the most important aspects of PFAS analysis is paying attention to minute details to reduce potential sources of contamination.

How was high-pressure liquid chromatography (HPLC)–mass spectrometry (MS) analysis used in the detection of PFAS in drinking water?

LC–MS is the most commonly used analytical instrumentation for the detection of PFAS in aqueous environments. Liquid chromatography is best suited for the aqueous samples and allows for separation of the various PFAS of interest. The mass spectrometry setup specifically used for this analysis was a tandem setup, known as a triple quadrupole, which consists of two quadrupoles in series with a collision cell in between. This detector setup allows for filtering of specific mass transitions for each analyte (precursor/product ion), adding an extra layer of selectivity to the method.

Were techniques other than LC–MS used to detect PFAS in drinking water? If so, please describe what they were and how they differ from LC–MS.

While LC–MS is a very sensitive detection method on its own, however, there is still a need for sample preconcentration to detect the levels present in the environment. For this method, LC–MS was coupled with solid phase extraction (SPE). The PFAS present in a sample are retained on a solid sorbent and reconstituted in a smaller volume, allowing for preconcentration. With this method, roughly 250 mL of a sample is collected and resuspended in 1 mL after extraction, creating a 250:1-fold preconcentration.

How does EPA method 537.1 change the process by which PFAS are detected?

There are several other approaches to analyze PFAS, some examples being combustion ion chromatography for total organic fluorine analysis and gas chromatography–mass spectrometry (GC–MS). However, in recent years the use of LC–MS for PFAS detection has been the main analytical instrumentation used in the field. EPA 537.1 differs in that it is a validated method for the detection of PFAS specifically in drinking water.

Apart from the detection of PFAS in drinking water, are there other instances in which EPA 537.1 can be used to detect PFAS?

The EPA developed 537.1 solely for the detection of PFAS in drinking water, which is one of the major focuses right now in the field. Ideas from 537.1 could be taken and applied for the detection of PFAS in other aqueous environmental sources. There are other validated methods that the EPA is working on to detect PFAS in different sources. One such example is draft method 1633 published in August 2021 for the detection of PFAS in aqueous, solid, biosolids, and tissue samples by LC–MS.

What are your next steps in PFAS contamination detection and method development?

LC–MS is a mature technology for the detection of PFAS. Moving forward, the focus will be on getting a better understanding of the full extent of the problem. Method 537.1 only covers detection of 18 selected PFAS, however, there are currently more than 5000 compounds in the group that have been identified. An additional focus in the future will be on improving method throughput.

A. Belunis, and W.R. LaCourse, “EPA 537.1 Method Validation for the Detection of Per- and Polyfluoroalkyl Substances (PFAS) in Drinking Water Sources,” University of Maryland, (2021).

 is a PhD candidate in the department of Chemistry and Biochemistry at the University of Maryland, Baltimore County (UMBC). She has a Bachelor of Science degree in Forensic Chemistry from Towson University. Her experience includes working with instrumentation, sample preparation techniques, and method development for a wide range of applications. Her current research project focuses on method development using LC–MS/MS for the investigation of PFAS in various environmental sources.

Detecting Environmental PFAS Using Liquid Chromatography–Tandem Mass Spectrometry

The U.S. Environmental Protection Agency (EPA) Administrator, Michael S. Regan, recently announced the initiation of the agency’s “Strategic Roadmap” to address the issue of contamination with per- and polyfluoroalkyl substances (PFAS). An analysis conducted by the EPA Council on PFAS established by Regan in April 2021 resulted in the creation of the Roadmap.

The EPA’s Roadmap focuses on three guiding strategies: increasing investments in research, leveraging authorities to take immediate action to restrict PFAS chemicals from being released into the environment, and accelerating the cleanup of PFAS contamination.

As part of the plan, the EPA also announced a new national testing strategy that requires PFAS manufacturers to provide the agency with toxicity data and information on categories of PFAS chemicals. The PFAS to be tested will be selected based on an approach that breaks the large number of PFAS into smaller categories based on similar features, and the approach will consider what existing data are available for each category. The initial set of test orders for PFAS will be strategically selected from more than 20 different categories of PFAS. This set of orders will provide the agency with critical information on more than 2000 other similar PFAS that fall within these categories.

The Roadmap sets aggressive timelines for enforceable drinking water limits under the Safe Drinking Water Act. It creates a hazardous substance designation under CERCLA [define], to strengthen the ability to hold polluters financially accountable, and timelines for action—whether it is data collection or rulemaking—on Effluent Guideline Limitations under the Clean Water Act for nine industrial categories.

Additionally, the Roadmap initiates a review of past actions on PFAS taken under the Toxic Substances Control Act to address those that are insufficiently protective It allows for increased monitoring, data collection, and research, and it includes a final toxicity assessment for GenX, which can be used to develop health advisories that will help communities make informed decisions to better protect human health and ecological wellness. Efforts to build the technical foundation needed on PFAS air emissions to inform future actions under the Clean Air Act will continue under the Roadmap.

For further information about the PFAS Strategic Roadmap, visit 

The U.S. Environmental Protection Agency (EPA) Administrator, Michael S. Regan, recently announced the initiation of the agency’s “Strategic Roadmap” to address the issue of contamination with per- and polyfluoroalkyl substances (PFAS). 

EPA Creates Strategic Roadmap to Address PFAS Contamination

You're invited to publicize your 2021–2022 new product introductions in 

. Here's how to get your products included.

 For our 2022 review, you may submit any product launched between May 2021 and March 2022.

We have four forms, covering different types of products. Participate in as many categories as you wish. Limit 5 products per category.

Links to the surveys appear below. Please download the forms you need, fill them out, and send them to 

Click on the links below to download the forms:

HPLC and Mass Spectrometry Systems, Modules, and Data Software

Sample Preparation Products and Accessories


Download the forms online and email all materials to: John Chasse, Managing Editor at 

If you are unable to complete the forms yourself, please forward them to the appropriate person. If your company distributes products for other companies, please send this announcement to the manufacturer.

Include examples of appropriate chromatograms or other technical data.

Information on every product you submit will be held in strict confidence prior to publication.

Careful consideration will be given to all surveys received. Submitted information will be held in confidence until publication. Final decisions regarding what details are included for publication is based on editorial judgment, reader interest, and available space.

You're invited to publicize your 2021–2022 new product introductions in LCGC. Here's how to get your products included.

LCGC 2022 New Product Review – Call For Submissions

Analysis of polyaromatic hydrocarbons (PAHs) in air demonstrates that a thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) system can operate with hydrogen carrier gas as well as it does with helium.

Elinor Hughes obtained her B.Sc. in chemistry and Ph.D. in organic chemistry at Bangor University, UK. After working for a chemical manufacturing company for three years, she moved to the Royal Society of Chemistry where she worked in journals publishing for six years and on Chemistry World magazine for four years. This was followed by five years as a freelance copyeditor and science writer. Her current role is technical copywriter at Markes International.

Many semivolatile organic compounds (SVOCs) are considered hazardous to human health, including some phthalates (1) and benzo[a]pyrene (a five‑ring PAH), a toxic air pollutant of interest to regulators both sides of the Atlantic (2,3).

However, traditional reference methods for measuring SVOCs in ambient air (4) are cumbersome and prone to high uncertainty (5,6). They typically involve using large pumps to draw large volumes (up to hundreds of millilitres) of air through filters backed by polyurethane foam, XAD‑2, or other similar sorbents, then Soxhlet extraction and steam distillation followed by gas chromatography–mass spectrometry (GC–MS) analysis.

As thermal desorption (TD)–GC–MS technology has evolved over the years, its compatibility with increasingly higher‑boiling compounds has improved (7). Now, TD-based methods provide a reproducible, readily automated, and convenient alternative approach for monitoring SVOCs in ambient air in non‑dusty environments (8–16). Sample volumes in the order of 500 L are typically collected over a 24-h period using conventional small (personal monitoring) pumps at a rate of 350 mL/min. Subsequent TD–GC–MS analysis harnesses the SVOC recovery of modern TD technology and is suitable for GC‑compatible SVOCs with volatilities above n-C44 (b.p. > 500 °C). Example compound classes include polychlorinated biphenyls (PCBs), phthalates (up to and including didecylphthalate), polyaromatic hydrocarbons (PAHs), high-boiling hydrocarbons, and some polybrominated flame retardants (8–16).

With the latest enhancement to TD technology being certification for operation with hydrogen carrier gas, an investigation was carried out to see if there were any benefits or drawbacks of using hydrogen when measuring SVOCs. PAHs were selected as test compounds as they are particularly “sticky” and challenging. A PAH study using conventional helium carrier gas provided the basis for comparison (17).

Why Consider Switching to Hydrogen Carrier Gas?

Helium is a finite resource that is increasingly expensive and difficult to source as a GC carrier gas. In addition, it must be extracted and stored before being shipped around the world, giving it a high carbon footprint. Hydrogen, on the other hand, is simple to generate using water and electricity and would seem to be an obvious environmentally friendly alternative, securing against helium shortages in the long term and offering immediate cost savings. It also promises shorter analytical cycle times and faster sample throughput. It is important to test the impact of hydrogen carrier gas on system performance with SVOCs. No TD features or functions are compromised by using hydrogen and all multi-gas thermal desorbers can also be used with helium or nitrogen carrier gas without changing system hardware. Also, they can be connected to any hydrogen-ready GC and MS instruments.

Using the chromatographic conditions reported in reference 17 as a starting point, clean sorbent tubes (Markes International “High-boiler” tubes: part number C2-CAXX-5138) were loaded with a 16-component PAH standard (10 ng/µL) using a calibration solution loading rig (Markes International; see reference 18 for method). The TD method was developed and optimized in a short iterative process (see reference 19 for method). The GC conditions selected for use with helium were translated to conditions for hydrogen carrier gas using software that is available free-of-charge online (20). The objective of this phase of the study was to achieve analyte recovery levels and chromatographic resolution with hydrogen carrier gas equivalent to those achieved with helium previously (17). The results are shown in Figure 1.

 TD: instrument: TD100-xr (Markes International), focusing trap: ‘high-boiler’ tubes, tube desorption: 320 °C (15 min) with 50 mL/min tube and trap flow (no inlet split), trap desorption: –10 °C to 350 °C (10 min) at maximum heating rate, outlet split flow: 50 mL/min, flow path: 250 °C; GC: column: 30 m × 0.25 mm, 0.25-μm, DB-5ms (Agilent), column flow: 3 mL/min, oven ramp: 50 °C (1 min), then 15 °C/min to 100 °C, then 20 °C/min to 240 °C, then 10 °C/min to 260 °C (6 min), then 50 °C/min to 310 °C (5 min), inlet: 320 °C; MS: aux heater: 320 °C, ion source: 250 °C, SIM/scan analysis: 

TD: instrument: TD100-xr Multi-Gas (Markes International), focusing trap: ‘high-boiler’ tubes, tube desorption: 320 °C (10 min) with 50 mL/min tube and trap flow (no inlet split), trap desorption: –10 °C to 350 °C (5 min) at maximum heating rate, outlet split flow: 50 mL/min, flow path: 250 °C; GC: column: 30 m × 0.25 mm, 0.25 μm, DB-5ms (Agilent), column flow: 3 mL/min, oven ramp: 50 °C (0.65 min), then 22.4 °C/min to 100 °C, then 30 °C/min to 240 °C, then 15 °C/min to 260 °C (6 min), then 74.5 °C/min to 310 °C (3.35 min), inlet: 320 °C; MS: aux heater: 320 °C, ion source: 250 °C, SIM/scan analysis: 

 The data obtained showed the expected significant gain in chromatographic efficiency without compromising resolution or sensitivity. Furthermore, it was found that complete recovery of the highest-boiling six-ring PAHs through the desorber could be achieved with 40% shorter desorption times using hydrogen compared with helium carrier gas—15 min with hydrogen versus 25 min using helium (Figure 2).

As the automated thermal desorber offered overlap mode—that is, it allowed the desorption of a subsequent sample to begin while GC–MS analysis of the previous sample continued—GC cycle times became the most important factor dictating system productivity. Figure 3 illustrates the improvement in sample throughput that can be achieved by using hydrogen carrier gas for this SVOC application. Broadly speaking, deployment of hydrogen carrier gas instead of helium allowed the analysis of at least one extra SVOC sample per hour.

System performance was evaluated
for peak shape at low levels, linearity, limits of detection and quantification
(LOD and LOQ), and reproducibility. The use of quantitative sample re-collection and repeat analysis was also evaluated as a means of validating analyte recovery.

The results showed exceptional peak shapes, even at low picogram (pg) levels for each compound of interest. Figure 4 presents four examples of PAHs across the chromatogram from naphthalene to benzoperylene, showing excellent peak shapes even at 0.6 pg on the column. Linearity (R2) was greater than 0.995 for all compounds across the full volatility range for a concentration range of 0.01–10 ng standards (Figure 5). The results also showed exceptional sensitivity. Assuming air was sampled at 333 mL/min, allowing the collection of 480 L over 24 h (17), all LOQs were below 0.08 ng/m3 and all LODs were below 0.025 ng/m3 (Table 1). This demonstrates comparable results to those previously found with helium (17), and therefore no loss in sensitivity. Excellent reproducibility was obtained, as demonstrated in Figure 6 where 10 replicate analyses are overlaid and show a high degree of consistency for both retention time and intensity.

To validate analyte recovery, a standard (10 ng/µL) was re-collected and the analysis repeated several times. This process tests the entire TD–GC–MS workflow and is recommended in international standard methods such as ISO 16000-6 (21). If compound losses do occur, for example due to compound decomposition, hydrogenation, adsorption, or condensation, it would result in the affected peak area being smaller than expected in the repeat analysis, that is, smaller than that predicted from the split ratio or relative to other peaks in the mix. The data is shown in Figure 7 and demonstrates excellent recovery (17), that is, > 99% recovery across the PAH volatility range when using hydrogen as a carrier gas.

This study has shown that the excellent performance of multi-gas-enabled thermal desorption for PAHs can be comfortably replicated using hydrogen carrier gas. Further, the results from this study have shown that using hydrogen significantly speeds up the overall analysis, offering both improved desorption efficiency and faster chromatographic separations with no significant downsides in terms of loss in sensitivity, reactivity, or method reproducibility. Moreover, important analytical quality control checks, such
as quantitative sample re-collection for repeat analysis and validation of analyte recovery, have been shown to work just as effectively on the TD systems configured with hydrogen carrier gas as with helium.

In conclusion, it is important to consider that many other important advantages can be realized by switching to hydrogen. These include significant cost savings—hydrogen cylinders are between 6 and 10 times less expensive than helium cylinders and can be replaced by hydrogen generators for even bigger long-term savings. Lowering high-temperature desorption times on the TD and time spent by the GC column at maximum temperature protects system components, extending maintenance intervals and lowering levels of system background artefacts. The extra desorption efficiency of hydrogen can either be used to speed things up (as described in this study) or it can be used to achieve the same recovery within the same time but at lower temperatures. This is often preferred in trace-level studies, for example, where the most important factor is minimizing background rather than productivity or cycle times.

Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation, and Restriction of Chemicals (REACH), https://www.legislation.gov.uk/eur/2006/1907/contents.

Directive 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium, mercury, nickel, and polycyclic aromatic hydrocarbons in ambient air, https://www.legislation.gov.uk/eudr/2004/107/contents.

J. Chunrong, F. Xianqiang, L. Smith, and R. Rogers, Characterizing community exposure to atmospheric polycyclic aromatic hydrocarbons (PAHs) in the Memphis tri-state area, https://www.epa.gov/sites/default/files/2020-01/documents/memphis_pahs_study_final_report_08.pdf.

EN ISO 16000-13, 2008, Indoor Air – Part 13: Determination of total (gas and particle-phase) polychlorinated dioxin-like biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/PCDFs) – Collection on sorbent-backed filters, https://www.iso.org/obp/ui/#iso:std:iso:16000:-13:ed-1:v1:en.

T.F. Bidleman, W.N. Billings, and W.T. Foreman, 

C. Schauer, R. Niessner, and U. Pöschl, 

, C.F. Poole, Ed. (Elsevier, 2021), pp. 267–323.

E. Wauters, P. Van Caeter, G. Desmet, F. David, C. Devos, and P. Sandra, 

Environmental Science and Pollution Research

Markes Application Note 053, The performance of thermal desorption for the analysis of high-boiling SVOCs.

Markes Application Note 136, The performance of thermal desorption for the quantitative analysis of long-chain hydrocarbons.

Markes Application Note 137, Quantitative determination of semi-volatile polychlorinated biphenyls (PCBs) using TD–GC–MS.

Markes Application Note 138, A robust TD–GC–MS method for the determination of trace-level phthalate esters in air – Method validation and field study.

Markes Application Note 139, High-performance analysis of polycyclic aromatic hydrocarbons (PAHs) by TD–GC–MS: Method validation and case-study.

Markes Application Note 140, Quantitative analysis of airborne semi-volatile flame retardants using sorbent tube sampling with TD–GC–MS.

Markes Application Note 007, Preparing and introducing standards using thermal desorption.

Markes Application Note 021, Developing and optimising tube-based thermal desorption methods.

EZGC tool, Restek: https://ez.restek.com/ezgc-mtfc

ISO 16000-6:2011 Indoor air — Part 6, Determination of volatile organic compounds in indoor and test chamber air by active sampling on Tenax TA sorbent, thermal desorption and gas chromatography using MS or MS-FID, https://www.iso.org/standard/52213.html.

 is a senior application specialist in the thermal desorption business unit at Markes International. Laura is responsible for developing new methods and testing Markes’ suite of thermal desorbers for new and emerging applications. Laura joined Markes as a customer support specialist in 2014 before moving to work in application development. As part of her current role, Laura works closely with key opinion leaders in collaborations across a variety of market areas, and she has a particular specialism in environmental analysis, breathomics, and defence and forensics.

obtained her B.Sc. in chemistry and Ph.D. in organic chemistry at Bangor University, UK. After working for a chemical manufacturing company for three years, she moved to the Royal Society of Chemistry where she worked in journals publishing for six years and on 

 magazine for four years. This was followed by five years as a freelance copyeditor and science writer. Her current role is technical copywriter at Markes International.

Analysis of polyaromatic hydrocarbons (PAHs) in air demonstrates that a TD–GC–MS system can operate with hydrogen carrier gas as well as it does with helium.

How Switching from Helium to Hydrogen Carrier Gas in Thermal Desorbers Enhances Gas Chromatography–Mass Spectrometry Systems

The 13th Multidimensional Chromatography Workshop is a free event involving keynote presentations, contributed presentations, and discussion groups on all multidimensional techniques, and is happening virtually on 31 January–2 February 2022. The workshop welcomes both experts and new users to the field for training, networking, and sharing the latest trends. Keynote lecturers will present on major trends in both multidimensional gas chromatography (GC) and multidimensional liquid chromatography (LC), from the point of view of both academic and industry research.

Participants will be able to choose from several focus group discussions intended to stimulate discussion on key areas of the field. The full programme has been released and indicates concurrent sessions on popular topics including modulation technologies and data analysis. The programme will also include concurrent poster sessions on different application areas. Presenters will be eligible for three poster awards:

Multidimensional GC Poster Award—Sponsored by the American Chemical Society’s Subdivision on Separations Chemistry and Chromatography—$250 USD Student Award

Multidimensional LC Poster Award—Sponsored by the American Chemical Society’s Subdivision on Separations Chemistry and Chromatography—$250 USD Student Award

Industrial Research and Development Poster Award—Sponsored by CerTech—€250

This year, the workshop will highlight the work of four keynote speakers. The speakers come to us with experience in either multidimensional gas chromatography (GC) or multidimensional liquid chromatography (LC), and they represent both academic research and industry sectors. In addition, we have asked all the keynote speakers to address the following questions in their presentations to get their perspective on the evolution of multidimensional chromatography:

What sparked your interest in multidimensional chromatography?

What was the moment you were convinced that multidimensional chromatography was a valuable solution to adopt?

What is the biggest challenge facing the field of multidimensional chromatography?

What is the most interesting application of multidimensional chromatography you have seen in the last year?

Why does multidimensional chromatography matter?

Robert E. Synovec, Professor, University of Washington

Implementation of Tile-Based Fisher Ratio Analysis with GC

GC–TOF-MS Datasets: Current Status and Future Prospect

Robert E. Synovec is Professor of Chemistry at the University of Washington (UW) in Seattle (Washington, USA). He obtained his Ph.D. in 1986 from Iowa State University, and then joined the UW faculty that year. He served as Associate Chair of the Chemistry Graduate Education Programme from 2007–2020. Synovec has graduated 45 PhDs, 4 thesis masters, and 8 non-thesis masters students, with 10 postdocs and 60 undergraduate researchers. His group pioneers the development of novel analytical instrumentation and methodology based upon chemical separation science coupled with chemometric data analysis. The group investigates the basic principles of separation science, detection, and data analysis at both a fundamental and problem-solving level. He has over 270 publications and over 620 research presentations, which includes over 250 invited lectures and invited presentations. In May 2013, Synovec was awarded the GC×GC Scientific Achievement Award at the 10th GC×GC International Symposium. This award has been instituted to recognize the pioneering contributions of key scientists in promoting GC×GC instrumentation, method development, and/or applications. In May 2016, Synovec received the Marcel Golay Award at the 40th ISCC meeting in Riva del Garda, Italy, which is presented annually to a scientist in recognition
of a lifetime of achievement in capillary chromatography.

Petr Česla, Associate Professor, University of Pardubice

Optimization of Microcolumn Two‑Dimensional LC—Towards Highly Sensitive Separation

​​Petr Česla is Associate Professor of Analytical Chemistry at the Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice. His research work focuses on the development of separation techniques in the liquid phase, mainly LC and capillary electrophoresis (CE), with special attention on two-dimensional separations, optimization procedures, data processing, and coupling of LC and CE to mass spectrometry (MS). He has been engaged in many research projects and acts as Principal Investigator for several projects for the Czech Science Foundation. He is author of more than 45 papers in scientific journals with 850 citations, and co-author of one book and two book chapters. He was supervisor of 20 diploma and 14 bachelor theses and currently supervises three Ph.D. students.

Melissa Dunkle, Research Scientist, Dow Benelux BV

GC for Industrial Applications: The Good, The Bad, and The Ugly

​​Melissa received her Ph.D. degree in 2007 under the direction of Luis A. Colón from the Department of Chemistry at the University at Buffalo, New York, USA. She then completed a two year postdoc at Ghent University in Belgium under the direction of Pat Sandra. In 2009, Melissa accepted a role as GC Specialist at the Research Institute for Chromatography (RIC) in Kortrijk; she then joined Dow Benelux BV in 2015 in Analytical Science, Core R&D.Her expertise includes liquid chromatography–high‑resolution mass spectrometry (LC–HRMS, MS/MS), gas chromatography coupled to various detector technologies (GC–flame ionization detection [FID], GC–MS, GC–[HR] time‑of‑flight [TOF]‑MS, GC–vacuum ultraviolet [VUV]), supercritical fluid chromatography (SFC), and multidimensional chromatography (LC×LC and GC×GC). In her current role, Melissa leads various research projects to advance analytical capabilities and improve the evaluation of natural gas and circular feedstocks.

Alexandre Goyon, Senior Scientist, Genentech

2D-LC Analysis of Oligonucleotides: From Their Conventional Analysis at the Intact Level to an Integrated Bottom-Up Approach

Alexandre Goyon is Senior Scientist in the Genentech Research and Early Development (gRED) organization. He received a Ph.D. degree in pharmaceutical analytical chemistry in 2019 from the University of Geneva, Switzerland. He has published 32 peer‑reviewed papers and he is the first author of 19 of them. His team supports early- and late-stage research​.

This year, the workshop will host small focus groups to discuss the landscape of three narrower topics appearing to gain attention in the field of multidimensional chromatography. Attendees will choose one of the sessions to attend and contribute to the discussion. This will also be an opportunity for individuals to interact more easily in smaller groups to learn more about certain topics or to contribute their expert opinions. Focus groups will be moderated by experts in multidimensional separations to lead the conversation.

 Who is doing it? What are the combinations being used? What are the benefits? What are the drawbacks? What is the difference in how they are used most commonly for multidimensional GC vs. multidimensional LC?

How do you optimize your separation? Who is performing full optimization for every study? Are users moving towards a standard column set for various applications? Do newcomers need to know how to do robust optimization to get started?

Topic 3: External Software and Freeware Options:

 Who is using
freeware written using languages such as R or Python? What part of data processing can be done in these programs? What are the pros and cons of using freeware (validation, standardization)? What are the benefits and drawbacks of external software vs. embedded approaches being developed?

In preparing for the conference, we released a survey to ask participants—why does multidimensional chromatography matter? We hope to understand this question in greater detail at the end of the conference, but so far, respondents felt that multidimensional chromatography was helpful to:

Diversify the tools they are able to use to solve chemical problems;

Find what is unknown in the most complex samples.

Registration is completely free of charge and can be completed at www.multidimensionalchromatography.com. We hope that you will join us for this exciting event, whether you are looking to find out what multidimensional chromatography is all about, looking to improve your skills in multidimensional separations, or hoping to improve your network in the field of multidimensional chromatography.

is at Chaminade University of Honolulu, Hawaii.

is at Gustavus Adolphus College, St. Peter, Minnesota, USA.

The 13th Multidimensional Chromatography Workshop is a free virtual event involving keynote presentations, contributed presentations, and discussion groups, and is happening virtually on 31 January–2 February 2022.

The 13th Multidimensional Chromatography Workshop: Why Does Multidimensional Chromatography Matter?

This month we interview Hedvika Raabová, a graduate student at the Charles University, Faculty of Pharmacy in Hradec Kralove, Czech Republic, about her work using novel micro- and nanofibres during sample preparation, and the concept behind composite micro-/nanofibre extractions.

Q. When did you first encounter chromatography and what attracted you to the subject?

The first time I came across a chromatographic instrument was when I was working on my master thesis five years ago. At that time, it was mostly a “black box” where I inserted my samples in one end and the results came out the other. It was only during my graduate studies that I began to learn more about this separation technique. This understanding resulted from the topic of my Ph.D. thesis where liquid chromatography (LC) played an important role. Thus, I cannot tell for sure when I genuinely chose to work in this field of separation sciences, but I definitely do not regret it. I realized very quickly how flexible liquid chromatography can be depending on which approach is chosen. The repetitive, large-scale analyses can be done quickly and precisely. One just needs to place the samples in the instrument and push the start button. Or one can be more creative and try different mobile and stationary phases, add more columns, use various detectors, and thus move the work to the next level.

Q. Can you tell us more about your Ph.D. thesis?

My thesis dealt with the application of nanofibrous polymers as innovative sorbents for solid-phase extraction (SPE) coupled online with LC. The various nanofibrous polymers were manually filled into an extraction cartridge and this extraction unit was introduced into the chromatographic system. Then, the extraction and chromatographic analysis was performed and the extraction efficiency of the sorbents was evaluated from the peak areas. My Ph.D. thesis summarized all the theoretical and practical aspects of this topic. It included a description of sorbent fabrication procedures, modifications of the sorbent, and the comparison of the effectiveness of the polymer sorbents for different analytes. I described the challenges of the preparation of the extraction unit and discussed the pros and cons of nanofibrous extraction sorbents.

Q. What chromatographic techniques have you worked with?

I have to say, I am pretty conservative about the techniques I use. In my research I work mostly with high performance liquid chromatography (HPLC) or ultrahigh‑pressure liquid chromatography (UHPLC) systems and reversed-phase separation mechanism. Depending on the project, I use them in one‑dimensional or two-dimensional mode.

Q. Your primary focus concerns the use of novel micro- and nanofibres in sample preparation prior to separation via chromatography—what specifically attracted you to this area of research?

My current scientific focus was again more a lucky coincidence than a conscious decision. Since I have always enjoyed working in the laboratory, I wanted to complete my master thesis in the Department of Analytical Chemistry. The original task was just a simple analyte determination via HPLC. But at the same time, the initial experiments with nanofibres started in the department and my supervisor asked me to be part of the team. No one knew at that time if and how the extraction using nanofibres would work. This sparkle of uncertainty attracted me much more than the previous “safe” project and I started using nanofibres for the solid-phase extraction. First, the extractions proceeded separately, and the extracts were analyzed by LC to evaluate the extraction efficiency of the polymer fibres. The results were very promising, and it began to be clear to me that I would like to explore this topic a bit deeper. Therefore, I continued as a Ph.D. student.

Q. You have recently published a paper on polycaprolactone composite micro- and nanofibre material as an alternative to restricted access media (RAM) for extraction and separation of non-steroidal anti-inflammatory drugs from human serum (1). Could you tell us about this research? What do these novel polymer fibres offer over others available?

After all the elementary research with nanofibrous sorbents I had undertaken, I was curious to find some practical application. I finally had this opportunity when we confirmed that the composite micro/nanofibres extracted the analytes from cow milk and human serum with minimal prior treatment of those matrices. The analytes I chose were the non‑steroidal anti‑inflammatory drugs because they are common medication. It was also easy to obtain real-life samples from the local hospital. They are also administered in tens or even hundreds of milligrams doses, so the UV detector we used was sensitive enough to aid in detection. In the end, we had a method for online extraction of ibuprofen, ketoprofen, naproxen, and diclofenac from human serum that was used for diclofenac determination in a real-life serum sample. There is still a long way to go, but I feel that the nanofibrous sorbents are a bit closer to common application in analytical laboratories after publication of this study. We achieved great results with the composite micro/nanofibres that were comparable to the silica sorbents. Unlike purely nanofibrous sorbents, the composites have better mechanical stability and are therefore suitable for online extractions in high-pressure systems.

Q. Can you talk about the concept behind composite micro/nanofibre extractions?

As I mentioned before, the greatest advantage of this composite material is its mechanical stability. When we started using nanofibres for online extraction, it was hard to achieve a repeatable result as the sorbents could not withstand the high back pressure. The fibres collapsed in the extraction unit, leading to increase of the void volumes, and the extraction did not work well. We solved the problem by combining the nano- and microfibres in the sorbent. The technology for production of these fibres was invented at the Technical University in Liberec (Czech Republic) with which we cooperate. The composite micro/nanofibrous material combines the mechanical stability of microfibres and the enhanced surface area of nanofibres. These benefits significantly improved the results of our experiments.

Q. What application areas could these novel polymer fibre materials be useful for?

This is a tricky question, and it would probably cost me another four years of research to demonstrate other application areas, even just for analytical chemistry and separation sciences alone. But as far as I know, these composite materials are applied in tissue engineering, and I believe that they can also be used as a filtration material in the industrial sector.

Q. Are there any challenges involved with using these novel materials for sample preparation?

Of course there are, and as our research progresses new ones are emerging all the time. However, I think the most crucial issues concerning the preparation of extraction cartridges have already been overcome, for example, cartridge leaking, fluctuation of mobile phase flow and back pressure, sorbent dissolution. Now, we continue working
on improvements in extraction efficiency and selectivity. Overall, in my opinion, dealing with the challenges is an inseparable part of the scientific research. If no challenges were left, it would be the end of the research.

I would like to point out that the nanofibrous sorbents should not be compared entirely with the commercial ones. The extraction using nanofibres has its own specifics, with some being beneficial while others are not. One day the fibrous sorbents may become an interesting alternative to the commercial products, but I do not think they can replace them completely.

Q. What are the emerging trends in sample preparation?

Sample preparation follows the global trend to do things better and faster. The trends are for miniaturized formats for sample pretreatment devices, which naturally results in the need for new sorbents. They must be very selective and provide a high extraction capacity as sample volumes decrease and so do the sorbent amounts. Scientists have already found many ways to achieve the desired sorbent properties, but the search for new materials is still ongoing. In addition, more sustainable approaches are becoming more and more valued in sample preparation. A reusability of nanofibrous sorbents and a biodegradability option for some of them support this trend.

Q. What projects are you working on next?

Actually, I also want to follow the trends in sample preparation and achieve more selective extractions using nanofibres. One idea is to link the specific antibodies on the fibre surface and proceed with the analyte extraction based on antigen-antibody interaction. I have not yet started because I have been busy with my Ph.D. thesis until now. Anyway, I want to give my full attention to this project at the beginning of 2022 and see how it goes.

H. Raabová, L. Chocholoušová Havlíková, J. Erben, J. Chvojka, F Švec, and D. Šatínský, 

 is a graduate student at the Charles University, Faculty of Pharmacy in Hradec Kralove, Czech Republic, where she also received her first degree in pharmacy in 2017. She has always been enthusiastic about the work in the laboratory and therefore chose to continue with her PhD studies at the Department of Analytical Chemistry. She became a member of Dalibor Satinsky’s research group, which are focused on the application of nanofibres for solid-phase extraction. This move was the beginning of her scientific journey in the separation sciences, and has led her mostly to liquid chromatography, with a small detour to a stay in a Swiss laboratory where she worked with capillary electrophoresis. With the same passion she has for the laboratory, she devotes herself to dancing, baking, and book reading.

This month we interview Hedvika Raabová, a graduate student at the Charles University, Faculty of Pharmacy in Hradec Kralove, Czech Republic, about her work using novel micro- and nanofibres during sample preparation, and the concept behind composite micro/nanofibre extractions.