Analytical science advances最新文献

Ammonium fluoride has been shown to improve sensitivity when using electrospray ionization (ESI) coupled with mass spectrometry (MS). Recent internal investigation furthered that claim, through the observation of improved sensitivity when analyzing steroid molecules. This work focuses on extending those observations to other small molecules to understand the impact ammonium fluoride has on detection sensitivity with optimized instrument conditions. Using conventional liquid chromatography ESI-MS we investigated sensitivity differences between ammonium fluoride, formic acid, or ammonium hydroxide as mobile phase additives. Full source optimization was performed for nine compounds at three different organic concentrations (30%, 60%, or 90%) with formic acid, ammonium fluoride, and ammonium hydroxide adjustment. Optimization results were compiled to generate individual methods by compound, polarity, mobile phase, and organic concentration. Flow injection analysis was performed with fully optimized methods to compare compounds across different solvent systems under optimal conditions. Negative ESI data showed 2–22-fold sensitivity improvements for all compounds with ammonium fluoride. Positive ESI data showed > 1–11-fold improvement in sensitivity for four of seven compounds and no change for three of seven compounds with ammonium fluoride. Ammonium fluoride improved ESI⁻ sensitivity for all compounds studied when using optimized source conditions. Investigation with ESI⁺ analyses showed mixed results, with four of seven compounds showing improvement and others showing equivalency or slight loss in sensitivity, suggesting potential sensitivity gains for some analogs with ESI⁺.

Through a collection of editorials titled “Emerging Scientists in Analytical Sciences,” we aim to spotlight promising individuals who are actively engaged in the realm of analytical sciences. For this editorial, we invited Niklas Geue who recently submitted his PhD thesis at The University of Manchester (UK). We are keen for anyone working in this field to nominate somebody for a Q&A by sending an email to one of the editors and explaining to us why this person should be highlighted.

I grew up in Magdeburg, a middle-sized city in East Germany, and went to a high school with a focus on maths, science, and technology. Thereby, I was exposed to a lot of science, and early on I participated in competitions, seminars, and other science events. My main interest was always chemistry, evidenced by a considerable lab in my grandparent's garage — much to everyone's annoyance. In my late high school years, I also participated in the International Chemistry Olympiad and made it to the final German selection round twice (among the best 16). The question of what I wanted to study was never really in doubt.

For my Bachelor's I went to Leipzig, a great student city, and graduated as the best student of my year. During and following my undergraduate years, I undertook three research internships. These experiences took me to diverse locations around the world: one internship was based in Santiago de Chile focusing on kinetics/spectroscopy (related to my Bachelor's thesis), another in Sydney centred around mass spectrometry (MS), and a third in Los Angeles, where I further worked on my spectroscopic skills. During these research stays, I realized two things: my strong inclination to remain within the realm of analytical and physical chemistry and my eagerness to actively engage in research at the earliest opportunity. The UK was ideally suited for the latter as I could start my PhD here directly after my Bachelor's. I was also always fascinated by how things work on a molecular level, and similarly enthusiastic about the interdisciplinarity with instrumentation and engineering. I became very interested in MS while I was in Australia, and decided that I wanted to stay in this field for my PhD work (Figure 1).

My PhD project is about the characterisation of metallosupramolecular complexes using advanced MS techniques. These and similar molecular architectures are important in a range of fields (e.g., catalysis, medicine, and materials), and quite prominent, not just since the Nobel prize for molecular machines in 2016. Unfortunately, it is not straightforward to structurally characterise them properly.¹ MS, particularly in combination with tandem MS and ion mobility (IM), is a great tool to enhance our understanding of such assemblies, by probing their stability as well as their size and shape.

During my PhD, I have successfully shown that it is possible to evaluate the stability of (metallo)supramolecular compou

Surface-enhanced Raman scattering (SERS) is a sensitive and fast technique for sensing applications such as chemical trace analysis. However, a successful, high-throughput practical implementation necessitates the availability of simple-to-use and economical SERS substrates. In this work, we present a robust, reproducible, flexible and yet cost-effective SERS substrate suited for the sensitive detection of analytes at near-infrared (NIR) excitation wavelengths. The fabrication is based on a simple dropcast deposition of silver or gold nanomaterials on an aluminium foil support, making the design suitable for mass production. The fabricated SERS substrates can withstand very high average Raman laser power of up to 400 mW in the NIR wavelength range while maintaining a linear signal response of the analyte. This enables a combined high signal enhancement potential provided by (i) the field enhancement via the localized surface plasmon resonance introduced by the noble metal nanomaterials and (ii) additional enhancement proportional to an increase of the applicable Raman laser power without causing the thermal decomposition of the analyte. The application of the SERS substrates for the trace detection of melamine and rhodamine 6G is demonstrated, which shows limits of detection smaller than 0.1 ppm and analytical enhancement factors on the order of 10⁴ as compared to bare aluminium foil.

Measurement of hormones is important for the diagnosis and management of endocrine diseases. The thyroid hormones thyroxine (T4) and triiodothyronine (T3) are among the most commonly measured hormones in clinical laboratories, and it is the concentration of free (not bound to proteins) thyroid hormones that is clinically most relevant. Free thyroid hormones are commonly measured using automated immunoassays, however, these are known to produce erroneous results due to interferences for some patients. Measurement of free thyroid hormones using equilibrium dialysis or ultrafiltration combined with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is considered a more accurate and robust method for free thyroid hormone analysis and overcomes many of the limitations of immunoassays. However, LC-MS/MS-based methods are often considered too technically difficult and not amendable to high throughput by clinical chemists and are not offered by many clinical laboratories. This mini-review aims to make it easier for clinical laboratories to implement LC-MS/MS-based measurement of free thyroid hormones. It describes the medical rationale for measuring free thyroid hormones, the benefits of LC-MS/MS-based methods with respect to interferences affecting immunoassay-based methods and physical separation methods. This mini-review highlights important parameters for ultrafiltration and equilibrium dialysis to obtain physiologically relevant free thyroid hormone concentrations and focuses on methods and devices used in clinical chemistry.

The 25^th Norwegian Symposium on Chromatography took place in September 2022 in Sandefjord, Norway. This conference was attended by approximately 200 participants from various sectors, including industry, hospitals, and academia. One of the parallel oral sessions organized was specifically dedicated to emerging PhD researchers and post-doctoral fellows. It was a pleasure to witness the exceptional quality of presentations and the enthusiasm displayed by the presenters. Consequently, the task of the jury, composed of Dr. Åse Marit Leere Øiestad from the Department of Forensic Sciences at Oslo University Hospital, Associate Prof. Cato Brede from the Department of Medical Biochemistry at Stavanger University Hospital, and Prof. Sebastiaan Eeltink from the Department of Chemical Engineering at Vrije Universiteit Brussel and Editor-in-Chief of Analytical Science Advances, was indeed challenging as they undertook the responsibility of selecting the best young scientist. After careful deliberation, Christine Olsen (Fig. 1) was chosen as the recipient of the award for an exceptional lecture addressing the key challenges and solutions to obtaining a sensitive and reliable determination of insulin secretion in stem cell-derived islets using conventional liquid chromatography (LC) with triple quadrupole mass spectrometry (MS). Interestingly, this was her first “live” presentation outside of the university following the coronavirus disease 2019 pandemic and zoom-conferences. Below is an interview with the recipient, where Analytical Science Advanced asked Christine Olsen questions about her PhD research as well as her general interests and hobbies.

My PhD research has primarily focused on developing a LC-MS method for the determination of glucose regulatory peptides. The main objective of our study is to characterize the production and secretion of insulin, somatostatin-14, and glucagon from stem cell-derived islets. This collaborative effort involves the Hybrid Technology Hub Center of Excellence at the University of Oslo and the Department of Transplantation Medicine at Oslo University Hospital. The combined research is aimed at gaining a deeper understanding of human islet cell biology and advancing the development of beta cell replacement therapy for type 1 diabetes, see Figure 2 for the workflow. The differentiation of human stem cells into mature insulin-producing islets may hold the potential to become an unlimited source of donor materials for patients with type 1 diabetes. As such, the characterization using highly specific LC-MS has been instrumental in contributing to this critically important research.

The take-home message from my lecture presented at the Norwegian Symposium on Chromatography was to highlight the significant impact of the non-defined adsorption of insulin when utilizing different tubing configurations in an LC-MS setup. The aim was also to emphasize the transformative possibilities that arise from elimin

Electromembrane extraction (EME) is a microextraction technique where charged analytes are extracted from an aqueous sample solution, through a liquid membrane, and into an aqueous acceptor, under the influence of an external electric field. The liquid membrane is a few microliters of organic solvent immobilized in a polymeric support membrane. EME is a green technique and provides high selectivity. The selectivity is controlled by the direction and magnitude of the electric field, the chemical composition of the liquid membrane and the pH. Recently, commercial prototype equipment for EME was launched based on the use of conductive vials, and interest in EME is expected to increase. The current article is a tutorial and discusses the principle and practical work with EME. The practical information is related to the commercial prototype equipment but is valid also for other technical configurations of EME. The tutorial is intended to give readers a fundamental understanding of EME, which is required for method development and operation, and for avoiding common pitfalls.

A common challenge when studying rare diseases or medical conditions is the limited number of patients, usually resulting in long inclusion periods as well as unequal sampling and storage conditions. The main purpose of this study was to demonstrate the challenges when comparing samples subject to different preanalytical conditions. We performed a global (commonly referred to as “untargeted”) liquid chromatography-high resolution mass spectrometry metabolomics analysis of blood samples from cases of sudden infant death syndrome and controls stored as dried blood spots on a chemical-free filter card for 15 years at room temperature compared with the same blood samples stored as whole blood at −80°C before preparing new dried blood spots using a chemically treated filter card. Principal component analysis plots distinctly separated the samples based on the type of filter card and storage, but not sudden infant death syndrome versus controls. Note that, 1263 out of 5161 and 642 out of 1587 metabolite features detected in positive and negative ionization mode, respectively, were found to have significant 2-fold changes in amounts corresponding to different preanalytical conditions. The study demonstrates that the dried blood spot metabolome is largely affected by preanalytical factors. This emphasizes the importance of thoroughly addressing preanalytical factors during study design and interpretation, enabling identification of real, biological differences between sample groups whilst preventing other factors or random variation to be falsely interpreted as positive results.

In 2017 integrated sampling and sample preparation for simplified liquid chromatography-mass spectrometry analysis of proteins from dried blood spots were introduced. The concept, called smart samplers or smart sampling, enables proteolysis or affinity clean-up, two common sample preparation steps in liquid chromatography-mass spectrometric bioanalysis of proteins, to start at the moment of sampling. The idea is to utilize the time for sampling and drying to perform these time-consuming and labour-intensive steps. Hence, only a simplified sample preparation is necessary after the arrival of the sample in the lab. In this perspective, we present an overview of the smart sampling approach where the conventional protein analysis workflow is reshuffled to start already prior to arrival in the lab. In addition, we present a thorough discussion of integrating sample preparation steps such as proteolysis or affinity capture in the sampling. Finally, in the end, we try to answer the question if conventional dried blood spots will become obsolete in the future.

In the modern world, energy and fuels are of utmost importance. Rapid characterization of petroleum and other hydrocarbon-based fuel is a well-researched field. Gas chromatography has traditionally been used to separate the different species and characterize the chemical content in fuels. Ideally, every molecule would be separated and characterized, but due to the complexity of the petroleum matrix, many compounds coelute. With the help of different detectors, more information can be gained, but there does not exist a single detector that can unambiguously differentiate and identify every compound. Vacuum ultraviolet spectroscopy (VUV) is a relatively new detector that can alleviate many limitations of other detectors. Based on spectroscopic absorption, VUV detection can provide qualitative and quantitative information regarding the composition of different fuels. It also provides certain advantages, allowing the deconvolution of coeluting peaks and differentiation between constitutional isomers. VUV has been used to classify the range of chemical components in many diverse fuel samples. Here, the contributions of VUV detection to petrochemical analysis to date are reviewed.

From September 4 to 6, 2022, the 25th Norwegian symposium on chromatography took place in Sandefjord, Norway. The meeting series is organized every second year under the auspices of the Norwegian Chemical Society, Department of Analytical Chemistry.

The biannual Norwegian symposium on chromatography is a key meeting for the Norwegian analytical chemistry environment. The series of chromatography symposia in Norway started in 1974 with a meeting in gas chromatography, and in 1980, the symposium changed name to the Norwegian symposium on chromatography to include all chromatographic techniques. Since then, meetings have been held regularly, biannually from 1982, in Sandefjord, Norway.

The Norwegian symposium on chromatography is known for a high scientific level, and for pleasant social activities including a symposium dinner and nightclub activities. With its mix of social and scientific program, it is a popular meeting place for the entire Norwegian chromatographic environment, gathering around 200 participants every time.

The 25th jubilee symposium was first postponed from January to September due to Covid-19 and, hence meeting restrictions. Luckily when September approached the Covid-19 restrictions were loosened and the symposium could be held as planned without restrictions in numbers and need for keeping distance.

The symposium started with an opening plenary lecture from Deirdre Cabooter (Catholic University of Leuven, Belgium) focusing on machine learning (e.g., deep learning) techniques to automate the different steps required to develop new LC methods. Her lecture was followed by a talk by Thomas Gundersen, CEO and co-founder of Vitas Analytical Services, Norway talking about his and his company's journey from a small start-up 30 years ago until being a recognized international contract research lab today. The other invited international speakers were Sebastiaan Eeltink (Free University of Brussels, Belgium), Charlotta Turner (Lund University, Sweden), Margrét Þorsteinsdóttir (University of Iceland, Iceland) and Jan H. Christensen (University of Copenhagen, Denmark) all giving excellent talks.

During the symposium dinner awards were given for the three best posters and the best oral presentation by a young scientist (the young scientist award). The latter award was co-sponsored by Analytical Science Advances. The winners of the poster awards were Christina Johannsen (University of Oslo) with her poster describing paper-based immunocapture in targeted LC-MS-based protein biomarker analysis, Alexander Bauer Westbye (Oslo University Hospital) presenting a method for determination of free thyroid hormones in serum by equilibrium dialysis LC-MS/MS and Sander Guttorm and Cristina Alexandrescu (University of Oslo) presenting how to evaluate the metabolome concentration stability on dried blood spot (DBS) cards by nuclear magnetic resonance (NMR) and LC-MS. The winner of the Young scientist award Christine Olsen