High-resolution Spectrometer Research Articles

Efficiency and resolution characterisation of a high-resolution bent crystal X-ray spectrometer using ray-tracing simulations

We report the characterisation of the efficiency and resolution of a high-resolution bent crystal spectrometer under Johannson geometry, using ray-tracing simulations. The spectral resolution is measured experimentally from electron-beam and fast ion-beam interactions with thin solid foils. The X-rays emitted by target atoms as well as projectile ions are studied. The results of the ray-tracing simulations are in very good agreement with the beam-foil spectroscopy experiments. The geometrical factors affecting the resolution are also discussed in detail. We also characterise the detection efficiency of the spectrometer by simultaneous measurements of X-rays using a semiconductor detector, i.e. Si(Li) detector, with known detection efficiency. These results are also compared with the ray-tracing simulation results.

Establishment and optimization of the three-band fluorometric indices for oil species identification: Implications on the optimal excitation wavelengths and the detection band combinations

BackgroundThe oil pollutants have become a major threat to the ocean environment with the rapid development of social economy and offshore production activities. The detection and identification of petroleum pollutants is the foundation and pre-requisite for controlling offshore oil pollution. Spectroscopic analysis using the ultraviolet–induced fluorescence of oil pollutants is a potential way for oil species identification. Nevertheless, the current fluorescence spectroscopic analysis methods, such as excitation-emission matrix, has high requirements on the detection equipment. There is a great need for rapid oil species identification method when it comes to practical applications. (93) ResultsThis study established the three-band fluorometric index (TBFI) method and examined its capability on the oil species identification. The fluorescence of five different types of oil samples under various excitation wavelengths were excited using a tuneable xenon lamp, and measured using a high-resolution spectrometer. The optimal excitation wavelengths and the corresponding detection band combinations were explored through the iterations of an optimal band combination algorithm through different excitation wavelengths. According to the results, three out of the four TBFIs tested in this study are suitable for oil species identification. They share the same sets of the excitation wavelengths under 365 nm, 375 nm, and 435 nm. The detection band combinations corresponding to each TBFI under each feasible excitation wavelength were also determined in this study. (125) SignificanceThe three-band fluorometric index method proposed in this study provides a feasible way for the rapid oil species identification using fluorescence spectroscopic analysis. The optimal excitation and detection wavelengths determined in this study also provide the theoretical basis for the designs of fluorescence sensors for rapid oil spill detection and identification. (51).

OR15-01 Overweight/Obese Pubertal Girls Have Higher Androgen Levels - Can Metabolomics Tell Us Why?

Abstract Disclosure: M. Calvert: None. S. Molsberry: None. A.K. Jarmusch: None. K.E. Overdahl: None. N. Shaw: None. Introduction: The Body Weight and Puberty Study (BWPS) was a 4-year longitudinal study of 90 healthy pubertal, pre-menarchal girls consisting of dual-energy x-ray absorptiometry to calculate total body fat (TBF), Tanner staging, breast ultrasound, and hormone tests. We observed that with time, girls with higher TBF demonstrated higher serum total and free testosterone and androstenedione levels. The cause of this association is unknown but is hypothesized to relate to greater insulin resistance. Methods: To investigate the association between higher androgens and higher TBF in late pubertal girls, we conducted an untargeted metabolomics study using our BWPS collection of 158 blood and 178 urine samples. Samples were run on an ultra-high performance liquid chromatograph (Vanquish, Thermo Scientific) coupled to a high-resolution mass spectrometer (Orbitrap Fusion Tribrid, Thermo Scientific) and analyzed in positive and negative ionization modes. We investigated the association between TBF or BMI Z-score and metabolites and the association between metabolites and serum androgen levels. All associations were examined cross-sectionally and lagged by one visit using linear generalized estimating equation models, adjusting for breast morphological stage and age at baseline, race, and time between visits. Benjamini-Hochberg false discovery rate (FDR) adjusted p-values were calculated to account for multiple testing. RaMP DB (Relational database of Metabolomic Pathways) was used to conduct enriched pathway analyses among metabolites nominally associated with body composition or hormone levels. Results: 70 participants (aged 10.9 ± 1.39 SD years; 60% White, 24% Black, 16% Other; 63% normal weight, 37% overweight/obese) contributed an average of 2.39 blood and 2.54 urine samples over the course of 1.15 ± 0.47 SD years of follow-up. While few metabolites were significantly associated with body composition or androgen levels after strict multiple testing correction, RaMP DB enriched pathway analyses identified several pathways linking TBF and androgen levels: 1) in lagged analyses of urinary metabolites, overall amino acid metabolism, arginine and proline metabolism, and the urea cycle linked TBF with androstenedione; 2) in cross-sectional analyses of serum metabolites, bile acid synthesis and metabolism, VEGF or extra-nuclear estrogen signaling (related to the metabolite, sphingosine-1-phosphate), and tryptophan metabolism linked TBF with androstenedione. Conclusions: Metabolomic analyses of samples from pubertal girls did not uncover signatures of insulin resistance (e.g., branched chain amino acids or C3- and C5-acyclcarnitines) to explain the association between higher androgens and TBF. Instead, we identified potential novel signaling pathways that may involve amino acid, bile acid, or sphingosine-1-phosphate action at the ovary and/or adrenal gland. Presentation: Friday, June 16, 2023

Realization and simulations of the new SPES Beam Cooler

One of the aim of the new project Selective Production of Exotic Species (SPES) is to produce and select new, neutron reach, isotopes [1,2,3,4]. The technique adopted to produce these species is the Isotope Selection On Line (ISOL) that postpones the separation of the isotopes after the beam production, using a High-Resolution Mass Spectrometer (HRMS).In order to allow a good separation of isotopes , the transverse emittance and the energy spread of the beam should have very low values, for this reason the Beam Cooler (BC) is located between the ISOL target, i.e. the beam source, and the HRMS.In the SPES project, where heavy isotopes are expected (mass number >100), the spectrometer resolution must be preferably higher than dm/m = 5 × 10-5 and thus the features of the beam at the entrance of the HRMS should be at least εn 95% < 8.3 × 10-3 π mm mrad and σE < 1.5 eV.BC devices are devoted to improve the beam features in terms of emittance and energy spread. A new BC has been designed and realized by the Laboratoire de Physique Corpuscolaire (LPC) at Caen, France, for the SPES facility at Laboratori Nazionali di Legnaro (LNL), near Padova, Italy.BCs cool down the beam thanks to a dissipative process in which the thermal energy passes from the beam ions to another medium whose constituent is typically much lighter, Helium gas in our case. This process takes place inside a confinement system that on the one hand to limit the spread of the cooling medium, and on the other to allow the beam to continue along the required trajectory, in the presented device it is a row of radio frequency quadrupoles in an almost closed chamber.Some specifications of the BC described in this document: the RFQ is 723 mm long, its internal radius is 5 mm; the RFQ is included in the gas chamber which is 730 mm×280 mm×220 mm. Before it there is the injection part composed by, following the beam trajectory, a grounded pipe (388 mm long) and three focusing electrodes. On the opposite side there is the extraction part with two focusing electrodes.This document presents the main features of the new BC together with the results of a preliminary study where the beam dynamic has been simulated. The analysis embeds also the investigation of the gas distribution inside and outside the BC.The beam dynamic simulations are based on the Simion code [5] while the estimation of the gas distribution is computed with MolFlow+ [6].Simulations show that accurately setting the BC leads to a large improvement of the emittance while the energy spread still needs to be improved. Limiting the gas pressure in the acceleration zone seems to allow the required final boost.

Ultrasonic assisted activation of persulfate for the treatment of spent porous biochar: Degradation of adsorbed PFOA and adsorbent regeneration

In this work, the regeneration of spent biochar adsorbent and the degradation of adsorbed PFOA by the system of ultrasonic assisted activation of persulfate were explored. The effects of ultrasound, persulfate and biochar on PFOA removal were investigated through a series of regeneration and degradation experiments. Meanwhile, the degradation mechanism and reaction pathways of PFOA were investigated with electron paramagnetic resonance (EPR) and high-resolution quadrupole orbitrap mass spectrometer. The results showed that PFOA adsorbed by biochar could be degraded efficiently with the synergistic effect of ultrasound and persulfate. The degradation of PFOA in biochar could be finished in 4 h, while the defluorination took longer, with a defluorination efficiency of 50.6% after 4 h and 99.6% after 10 h. In this process, PFOA was degraded and defluorinated gradually by thermal decomposition caused by cavitation bubbles and degradation caused by the attack of SO4•ˉ and •OH. Two different free radicals controlled different degradation pathways, with SO4•ˉ playing a dominant role. In this system, the regeneration of the waste biochar adsorbent was achieved by eliminating PFOA, which could be recycled more than three times. The application potential of the system was evaluated using real water sample, and it was found that the removal of PFOA in real water sample was satisfactory even with the influence of inorganic ions and organic matter, indicating that it has promising application prospects. This work provided new insight into the degradation of adsorbed PFOA and adsorbent regeneration.

Oxygen-bearing organic molecules in comet 67P’s dusty coma: First evidence for abundant heterocycles

The puzzling complexity of terrestrial biomolecules is driving the search for complex organic molecules in the interstellar medium (ISM) and serves as a motivation for many in situ studies of reservoirs of extraterrestrial organics, from meteorites and interplanetary dust particles to comets and asteroids. Comet 67P/Churyumov-Gerasimenko (67P), the best-studied comet to date, has been visited and accompanied for 2 yr by the European Space Agency’s Rosetta spacecraft. Around 67P’s perihelion and under dusty conditions, the high-resolution mass spectrometer on board Rosetta has provided a spectacular glimpse into this comet’s chemical complexity. For this work, we analyzed the O-bearing organic volatiles in unprecedented detail. Through a comparison of 67P’s inventory with molecules detected in the ISM, in other comets, and in soluble organic matter extracted from the Murchison meteorite, we also highlight the (pre)biotic relevance of different chemical groups of species. We report first evidence for abundant extraterrestrial O-bearing heterocycles (with abundances relative to methanol often on the order of 10% and a relative error margin of 30–50%) and various representatives of other molecule classes, such as carboxylic acids and esters, aldehydes, ketones, and alcohols. As with the pure hydrocarbons, some hydrogenated forms seem to be dominant over their dehydrogenated counterparts. An interesting example is tetrahydrofuran, as it might be a more promising candidate for searches in the ISM than the long-sought furan. Our findings not only support and guide future efforts to investigate the origins of chemical complexity in space, but they also strongly encourage the study, in the laboratory as well as by modeling, of such topics as the ratios of unbranched versus branched species and hydrogenated versus dehydrogenated species in astrophysical ice analogs.

Compact high-resolution spectrometer based on super-prism and local-super-collimation effects of photonic crystal.

We propose a design of the compact high-resolution photonic crystal (PhC) spectrometer with a wide working bandwidth based on both super-prism and local-super-collimation (LSC) effects. The optimizing methods, finding the ideal incident angle and oblique angle of PhC for a wider working bandwidth and ideal incident beam width and PhC size for a certain resolution requirement, are developed. Besides the theoretical work, for the first time, the experiment of such a PhC spectrometer is conducted in the microwave frequency range, and the beam-splitting effects for different frequencies in a wide working bandwidth agree very well with the theoretical predictions. According to the scalability, with the condition to control the deviations in the fabrication processes the design could be extended to optical frequency ranges, e.g., infrared, visible-light, and ultraviolet ranges. The spectrometer in optical frequencies can be implemented on silicon-on-insulator (SOI) chips as a thin-slab structure so that the operating bandwidth can be expanded further through the multi-layer design. Theoretically, the size of the ultra-high-resolution PhC spectrometer in optical frequency ranges based on our design could be two orders smaller than the traditional design.

Characterizing lignins from various sources and treatment processes after optimized sample preparation techniques and analysis via ESI-HRMS and custom mass defect software tools

Sample preparation of complex, natural mixtures such as lignin prior to mass spectrometry analysis, however minimal, is a critical step in ensuring accurate and interference-free results. Modern shotgun-MS techniques, where samples are directly injected into a high-resolution mass spectrometer (HRMS) with no prior separation, usually still require basic sample pretreatment such as filtration and appropriate solvents for full dissolution and compatibility with atmospheric pressure ionization interfaces. In this study, sample preparation protocols have been established for a unique sample set consisting of a wide variety of degraded lignin samples from numerous sources and treatment processes. The samples were analyzed via electrospray (ESI)-HRMS in negative and positive ionization modes. The resulting information-rich HRMS datasets were then transformed into the mass defect space with custom R scripts as well as the open-source Constellation software as an effective way to visualize changes between the samples due to the sample preparation and ionization conditions as well as a starting point for comprehensive characterization of these varied sample sets. Optimized conditions for the four investigated lignins are proposed for ESI-HRMS analysis for the first time, giving an excellent starting point for future studies seeking to better characterize and understand these complex mixtures.Graphical

High efficiency multilayer coated laminar gratings with high line density for tender X-ray region

Driven by the demand of high efficiency and high resolution monochromators and spectrometers in the tender X-ray range, high line density multilayer coated laminar gratings (MLLG) were designed, manufactured, and analyzed. Theoretical simulations displayed that a 5000 l/mm MLLG could realize high resolution at 3 keV and 40 times higher diffraction efficiency than the single-layer coated grating. For the first demonstration of the high line density MLLGs, two 3000 l/mm laminar gratings were fabricated and coated by Cr/C multilayers with different periodic thicknesses to achieve high efficiency (HE) and high resolution (HR) performance. For MLLG-HE, a maximum efficiency of 54.5% was achieved at 4.4 keV. For MLLG-HR, relatively high efficiency of 23.1%–38.6% were demonstrated with much stronger asymmetric diffraction in 2–4 keV, which can significantly increase the energy resolution of the system.

The AGATA Spectrometer

The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate a high-resolution gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. The tracking technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. AGATA can measure gamma rays from 10’s of keV to 10 MeV with excellent efficiency and position resolution and has a very high count rate capability. The realisation of AGATA and gamma-ray tracking is a result of many technical advances. AGATA has operated in a series of successful scientific campaigns at Legnaro National Laboratory in Italy, GSI in Germany and GANIL in France. AGATA is now in its next phase of development as it evolves to the full 4π instrument. It is presently starting its next campaign at Legnaro.

The structure of low-lying 1− states in 90,94Zr from (α,α′γ) and (p,p′γ) reactions

The low-lying dipole strength was investigated in 90,94 Zr via the (p,p′γ) reaction at 80 MeV and via the (α,α′γ) reaction at 130 MeV. These experiments were performed at the Research Center for Nuclear Physics (Osaka University) and made combined use of the high-resolution magnetic spectrometer Grand Raiden and the CAGRA HPGe gamma array. The comparison of our results with existing (γ,γ′) reaction data shows differences in the excitation patterns. In the present experimental conditions, in fact, both α and p probes are exciting the investigated 1− states mainly through the short-range nuclear force, expected to favour the population of surface excitations. Distorted Wave Born Approximation (DWBA) calculations were made using form factors built assuming specific transition densities, characterized by a strong neutron component at the nuclear surface and based on Random Phase Approximation (RPA). A combined analysis of the (α,α′γ) and (p,p′γ) data was performed to investigate the isoscalar character of the 1− states in 90,94Zr. Although an overall general consistency was obtained in the studied energy intervals, not all (p,p′γ) cross sections were well reproduced using the isoscalar strength deduced from (α,α′γ) data. This might suggest that the mixing of isoscalar and isovector components and the degree of collectivity are not the same for all the 1− states studied.

Effect of crystal structure on K shell binding energy of lead, mercury and tungsten using bremsstrahlung radiation

The K shell binding energies of lead, mercury, and tungsten in their pure elemental form and in some of their compounds have been measured for the first time by adopting a novel method. The method involves a weak beta source, an external bremsstrahlung converter, element and compound targets, and a high-resolution, high-purity germanium detector coupled to 16K multichannel analyzer. Continuous external bremsstrahlung photons produced by the interaction of beta particles from a 90Sr-90Y radioactive source with an iron foil are allowed to pass through the elemental and compound targets of lead, mercury, and tungsten. The spectrum of transmitted external bremsstrahlung photons is measured with a high-resolution high purity germanium detector spectrometer. The transmitted spectrum shows a sudden drop in intensity at K shell binding energy of the target. Such a sudden drop, which is due to the onset of the K shell photoelectric effect, has been used to determine the K shell binding energies. It has been investigated that the shifts in the K shell binding energies due to chemical environment of lead, mercury, and tungsten atoms is attributed to crystal structure.

Metabolomics analysis of visceral leishmaniasis based on urine of golden hamsters

BackgroundLeishmaniasis is one of the most neglected tropical diseases and is spread mainly in impoverished regions of the world. Although many studies have focused on the host’s response to Leishmania invasion, relatively less is known about the complex processes at the metabolic level, especially the metabolic alterations in the infected hosts.MethodsIn this study, we conducted metabolomics analysis on the urine of golden hamsters in the presence or absence of visceral leishmaniasis (VL) using the ultra-performance liquid chromatography (UPLC) system tandem high-resolution mass spectrometer (HRMS). The metabolic characteristics of urine samples, along with the histopathological change and the parasite burden of liver and spleen tissues, were detected at 4 and 12 weeks post infection (WPI), respectively.ResultsAmino acid metabolism was extensively affected at both stages of VL progression. Meanwhile, there were also distinct metabolic features at different stages. At 4 WPI, the significantly affected metabolic pathways involved alanine, aspartate and glutamate metabolism, the pentose phosphate pathway (PPP), histidine metabolism, tryptophan metabolism and tyrosine metabolism. At 12 WPI, the markedly enriched metabolic pathways were almost concentrated on amino acid metabolism, including tyrosine metabolism, taurine and hypotaurine metabolism and tryptophan metabolism. The dysregulated metabolites and metabolic pathways at 12 WPI were obviously less than those at 4 WPI. In addition, seven metabolites that were dysregulated at both stages through partial least squares-discriminant analysis (PLS-DA) and receiver-operating characteristic (ROC) tests were screened to be of diagnostic potential. The combination of these metabolites as a potential biomarker panel showed satisfactory performance in distinguishing infection groups from control groups as well as among different stages of infection.ConclusionOur findings could provide valuable information for further understanding of the host response to Leishmania infection from the aspect of the urine metabolome. The proposed urine biomarker panel could help in the development of a novel approach for the diagnosis and prognosis of VL.Graphical

Strontium monofluoride – a new molecule to measure fluorine using high-resolution continuum source flame molecular absorption spectrometry and its application for gasoline analysis

In this work, for the first time, strontium monofluoride was generated in an air-acetylene flame of a high-resolution continuum source molecular absorption spectrometer with the aim of fluorine determination via molecular absorption. The particular task was the determination of organic fluorine in gasoline/its components dissolved in xylene. Sequential measurements in the area of the most intensive absorption of the molecule were executed to select the spectral range for analysis. The acquired spectra differed from the ones from the literature, especially the emission spectra. The best and comparable sensitivity has been registered near 651 nm and 663 nm in measurements of rotations from the range of the X2Σ+ → A2Π electronic transition of the SrF molecule. Unfortunately, SrOH molecules were also spontaneously formed and absorbed radiation in the selected area. No other spectral interferences were found, except absorption by the SrBr molecule, which could have been formed in the flame despite a relatively low energy bond of 330 kJ/mol. The dependence of generation of the SrF and the SrOH molecules on the flame conditions was studied for pure solvent (xylene) and solutions of investigated samples of gasoline type. The effect of the SrOH molecule was overcome by blank subtraction or the least square background correction. The last method had to be used to overcome the SrBr effect. Due to the various combustion properties of various hydrocarbons and their different behaviour in flame, applying the simplified standard addition method became indispensable. As a source of strontium, an oil Sr standards or Sr acetylacetonate (SrAA) were investigated. The crucial benefit of SrF molecule application was the relatively good solubility (and relatively low price) of SrAA. Under the selected conditions, the characteristic concentration of fluorine was 1.9 and 2.0 mg/L, while the instrumental detection limit was 0.5 and 0.8 mg/L for the 651 and 663 nm ranges, respectively. The analytical technique enables the analysis of samples diluted to a small degree, e.g. 1:3 v:v and the best method detection limit is 1.3 mg/L. The proposed method is fast and cheap.

Electrochemistry-mass spectrometry bridging the gap between suspect and target screening of valsartan transformation products in wastewater treatment plant effluent

Degradation of xenobiotics in wastewater treatment plants may lead to the formation of transformation products with higher persistence or increased (eco-)toxic potential compared to the parent compounds. Accordingly, the identification of transformation products from wastewater treatment plant effluents has gained increasing attention. Here, we show the potential of electrochemistry hyphenated to liquid chromatography and mass spectrometry for the prediction of oxidative degradation in wastewater treatment plants using the antihypertensive drug valsartan as a model compound. This approach identifies seven electrochemical transformation products of valsartan, which are used to conduct a suspect screening in effluent of the main wastewater treatment plant in the city of Münster in Germany. Apart from the parent compound valsartan, an electrochemically predicted transformation product, the N-dealkylated ETP336, is detected in wastewater treatment plant effluent. Subsequently, a targeted liquid chromatographytandem mass spectrometry method for the detection of valsartan and its electrochemical transformation products is set up. Here, electrochemical oxidation is used to generate reference materials of the transformation products in situ by hyphenating electrochemistry online to a triple quadrupole mass spectrometer. Using this setup, multiple reaction monitoring transitions are set up without the need for laborious and costly synthesis and isolation of reference materials for the transformation products. The targeted method is then applied to extracts from wastewater treatment plant effluent and the presence of ETP336 and valsartan in the samples is verified. The presented workflow can be used to set up targeted analysis methods for previously unknown transformation products even without the need for expensive high-resolution mass spectrometers.

High-resolution compact spectrometer based on periodic tapered coreless fiber.

This Letter proposes a method that balances miniaturization and high performance of fiber optic speckle spectrometers. The periodically tapered coreless fiber is used as the scattering element to excite more higher-order modes in the coreless fiber. As a result, a remarkable spectral resolution of 0.03 nm in the near-infrared spectrum can be achieved with a 5-cm-long fiber. Narrow linewidth and broadband spectra in the wavelength of 1540-1560 nm are reconstructed separately, demonstrating the excellent performance of the designed all-fiber spectrometer. The spectral resolution of our proposed spectrometer is comparable to that of a 2-m multimode fiber spectrometer and has a significant improvement in miniaturization.

Chemical profiling and simultaneous quantification of major bioactive constituents from Cocculus hirsutus by UPLC-QqQ-MS

Cocculus hirsutus is a widely used herb in traditional systems of medicine for the treatment of various diseases. In the present study, five alkaloids (1–5), two flavonoids (6–7), one triterpenoid (8), and three steroids (9–10) were isolated from the roots of Cocculus hirsutus and further crude extract was analyzed by LC-Q-Tof-MS/MS in positive ionization mode leading to the identification of ten metabolites through comparison of exact molecular masses from their MS/MS spectra, mass fragmentation studies and with literature data. In addition, a method was developed and validated for the quantification of four bio-active compounds [Sinococuline (1), Magnoflorine (2), (E)-N-feruloyltyramine (3), and 20-Hydroxyecdysone (10)] using UPLC-QqQ-MS in multiple reaction monitoring (MRM) mode for the first time. The method has shown good linearity with correlation coefficients (r2) higher than 0.9916 for all four compounds. The intra- and inter-day precision were in the range of 0.3–6.1% and from 0.7% to 8.8%, respectively. The matrix effects of all the four analytes were found in the range of 94.7 ± 2.8–112.7 ± 3.7%. Overall, our study provides a reliable and rapid approach by hyphenated LC-MS/MS using high-resolution mass spectrometers for identification and quantification of bioactive constituents from the root extracts of Cocculus hirsutus.

Comparing the sensitivity of a low- and a high-resolution mass spectrometry approach for xenobiotic trace analysis: An exposome-type case study

The chemical exposome consists of environmental exposures experienced throughout a lifetime but to date analytical approaches to investigate the plethora of low-abundance chemicals remain very limited. Liquid chromatography high-resolution mass spectrometry (HRMS) is commonly applied in untargeted exposome-wide analyses of xenobiotics in biological samples; however, human biomonitoring approaches usually utilize targeted low-resolution triple quadrupole (QQQ) mass spectrometry tailored to a small number of chemicals. HRMS can cover a broader chemical space but the detection of molecules from low-level exposure amidst a background of highly-abundant endogenous molecules has proven to be difficult. In this study, a triple quadrupole (QQQ) and a high-resolution mass spectrometer (HRMS) with identical chromatography were utilized to determine the limits of quantitation (LOQ) of >100 xenobiotics and estrogenic hormones in pure solvent and human urine. Both instrumental platforms are currently applied in exposure assessment studies and were operated in their most frequently used acquisition mode (full scan for HRMS and multiple reaction monitoring for QQQ) to mimic typical applications. For HRMS analyses, the median LOQ was 0.9 and 1.2 ng/mL in solvent and urine, respectively, while for low-resolution QQQ measurements, the median LOQ was 0.1 and 0.2 ng/mL in solvent and urine, respectively. To evaluate the calculated LOQs in complex biological samples, spot urine samples from 24 Nigerian female volunteers were investigated. The higher LOQ values for HRMS resulted in less quantified low-abundance analytes and decreased the number of compounds detected below the LOQ. Even at chronic low-dose exposure, such compounds might be relevant for human health because of high individual toxicity or potential mixture effects. Nevertheless, HRMS enabled the additional screening for exposure to unexpected/unknown analytes, including emerging compounds and biotransformation products. Therefore, a synergy between high- and low-resolution mass spectrometry may currently be the best option to elucidate and quantify xenobiotics in comprehensive exposome-wide association studies (ExWAS).

Efficient mapping of lignin depolymerization product pools and quantification of specific monomers through rapid GPC-HPLC-UV/VIS analysis

BackgroundGrowing research on lignin depolymerization to functionalized bio-aromatics has necessitated dedicated analysis techniques. However, immense variability in molecular weight and functional groups of the depolymerization products impedes fast analysis of a large number of samples while remaining in-depth enough for catalyst screening or reaction condition optimization. While GPC-HPLC-UV/VIS has been a promising technique, up until now, the information it provides is largely qualitative. By enabling quantification of key monomeric products and through further reduction of overall analysis time, this study aims to increase the potential of GPC-HPLC-UV/VIS for fast and in-depth characterization of lignin depolymerization product pools. ResultsAnalysis of selected samples, isolated from GPC-HPLC-UV/VIS analyses of lignin depolymerization product pools, with gas chromatography (GC) equipped with an Orbitrap high-resolution accurate mass spectrometer (Orbitrap-HR/AM-MS) is successful in identifying the main low monomeric products. Moreover, these identifications are further substantiated through GPC-HPLC-UV/VIS analysis of standards. Furthermore, straight forward quantification of these products directly within GPC-HPLC-UV/VIS is successfully developed with limits of detection ≤0.05 mmol/L, which is at least on par with more complex analysis techniques. Additionally, several different reversed phase columns are assessed to reduce 2nd dimension (2D) time and, hence, overall analysis time while maintaining the possibility for quantification. A reduction in overall analysis time of about 30% as compared to the state-of-the-art is achieved by using a YMC Triart BIO C4 column as 2D. SignificanceThrough the enhancements introduced in this study, GPC-HPLC-UV/VIS emerges as a unique technique for the analysis of lignin depolymerization product pools, which is capable of fast yet sufficiently in-depth analysis of a large volume of samples. This capability is indispensable for catalyst screening and fine-tuning reaction conditions.

Label-Free Multiplex Proteotyping of Microbial Isolates.

To meet clinical diagnostic needs and for general microbiological screening, it is essential to be able to accurately and rapidly identify any microorganisms from complex microbiota. To gain insight into the individual components of microbiota, culturomics has been proposed as a means to systematically test hundreds of possible cultivation conditions and generate numerous microbial isolates with very distinct characteristics. High-throughput identification methods must now be developed to quickly screen these isolates. Currently, most multiplexing methods involve labeling, which comes at a cost. In this paper, we present an innovative label-free multiplexing method for the identification of microorganisms using tandem mass spectrometry. The method is based on offline reversed-phase fractionation of individual peptidomes. Multiplexing is achieved by mixing fractions of staged hydrophobicity; thus, each sample is mapped to specific elution times. In this proof-of-concept study, multiplexed samples were analyzed by tandem mass spectrometry in a single run and microorganisms present in the mixture were resolved by phylopeptidomics proteotyping. Using this methodology, up to 21 microorganisms could be identified in a single 60 min run performed with a Q-Exactive HF high-resolution mass spectrometer, resulting in a rate of one microorganism identified per 3 min of mass spectrometry, without any need for the use of labeling reagents. This approach opens new perspectives for the application of high-throughput proteotyping of bacteria using tandem mass spectrometry in large culturomics projects.