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Forensic document examination has been considered one of the most important fields in the forensic science. For this, a quick, effective, and cheap techniques for evaluation of forensic evidence is highly required. This study explores the comparison of A4 document paper by chemical and physical analysis. 16 of white A4 paper from different brands were analyzed by FTIR for investigation of structural characteristics. Video Spectral Comparator 8000 has been used to compare the A4 papers under different light source. The inorganic filler composition in the paper is also explored by ICP‐OES. The calcium carbonate content in document papers play a discriminant role which found to be between 16.02 % and 35.54 %. Also, water contact angle has been utilized in order to examine the surface of paper which is generally related to the inorganic filler and other additives. The WCA results ranged between 83° and 111° that enable quick and easy way to compare A4 document papers. The experimental results have demonstrated that besides FTIR methods, other methods such as ICP‐OES for elemental composition, WCA for wetting test, VSC for visualization under different light of source could have been applied for comparison of document papers in case of criminal cases. [ABSTRACT FROM AUTHOR]

Criminal practices in which an individual becomes vulnerable and prone to sexual assault after ingesting drinks spiked with doping substances have become a social concern globally. As forensic protocols require a multi‐tiered strategy for chemical evidentiary analysis, the backlog of evidence has become a significant problem in the community. Herein, a fast, sensible, and complementary dual analytical methodology was developed using a single commercial paper substrate for surface‐enhanced Raman spectroscopy (SERS) and paper spray mass spectrometry (PS‐MS) analysis to identify psychotropic substances added to alcoholic beverages irrefutably. To study and investigate this criminal practice, pharmaceutical formulations containing distinct psychotropic substances (zolpidem, clonazepam, diazepam, and ketamine) were added to drinks typically consumed at parties and festivals (Pilsen beer, açaí Catuaba®, gin tonic, and vodka mixed with Coca‐Cola Zero®). A simple liquid–liquid extraction with a low‐temperature partitioning (LLE‐LTP) procedure was applied to the drinks and effectively minimized matrix effects. As a preliminary analysis, SERS spectra combined with Hierarchical Clustering Analysis (HCA) provided sufficient information to investigate the samples further. The presence of the protonated species for the psychotropic substances in the spiked drinks was readily verified in the mass spectra and confirmed by tandem mass spectrometry. Finally, the results demonstrate the potential of this methodology to be easily implemented into the routine of forensic laboratories and to be further employed at harm reduction tends at parties and festivals to detect contaminated beverages promptly and irrefutably as an efficient tool to prevent such crimes. [ABSTRACT FROM AUTHOR]

The absolute dating of documents is still one of the most important challenges for forensic document examiners (FDE). The potential difference between the date on a questioned document and the actual year of production of the used paper can be only 1 to 5 years. Until now, there was no analytical method with this accuracy available. This study demonstrates a method for an absolute dating of paper by using the 14C bomb peak and dating the starch in the paper. Accelerator mass spectroscopy (AMS) radiocarbon measurements were performed on starch extracts and cellulose fibers from 50 paper samples with known production year from 1950 to 2018. For most of the paper samples, the measured 14C concentration values in the starch extracts were highly correlated with the data of the 14C bomb peak calibration curve. The differences between the calibrated ages and the actual harvest years of the starch‐containing plants were only up to 3 years. The 14C concentration in the paper fibers showed a lower but significant correlation with the production year of the papers and can be used to support the dating results of the starch extracts. In order to secure the accuracy of the dating, aside from the radiocarbon measurements of the extracted starch other analytical methods or data are used, like a detailed chemical analysis of the paper composition including fiber composition and the spectroscopic analysis of the purity of the starch extracts. In practice, only starch extracts without contaminations are used for the paper dating. [ABSTRACT FROM AUTHOR]

Raman microscopic measurements were used to analyse the detailed chemical composition and structure of three old papers dating from the 15th and 19th centuries. Raman mapping measurements were performed on the surface and along the cross‐section of the papers with a lateral resolution of 1 μm. The resulting Raman images visualise the detailed chemical structure of the papers including all components such as the different types of cellulose fibre, filler pigments, sizing agents, colour pigments and also inadvertently added trace particles, such as minerals or products of biological activity. The results of the paper analysis are discussed in connection with their use for the detailed characterisation and dating of paper. This study demonstrates the great potential and the possibilities offered by Raman microscopy or Raman imaging for chemical paper analysis. Raman microscopy allows new insights into the chemical composition and structure of old papers and could considerably enhance the understanding of former papermaking practices and also combat forgery and the fraud of documents and artworks on paper. [ABSTRACT FROM AUTHOR]

Here, we report a highly water‐soluble colorimetric and fluorescent pH probe that works in the pH range 0.2–3.0. The probe showed a rapid response, high stability, and excellent reversibility to acidity. Moreover, the fluorescence of probe was not influenced by the existence of high concentration of cations. The pKa of probe was calculated to be 2.25 ± 0.06. Furthermore, the pH test papers coated with the probe exhibited a distinct color change in acidic conditions. [ABSTRACT FROM AUTHOR]

Summary: The formation of advanced glycation end products (AGEs), regarded as a potentially harmful substance, in the protein glycation course is still under investigation. This study investigated the glycation modification of silver carp myofibrillar protein (MF) with glucose via Maillard‐driven chemistry. The resultant conjugates and glycation extent were characterised by chemical indicators, such as Fourier transform infrared spectroscopy, sodium dodecyl sulphate–polyacrylamide gel electrophoresis, colour development, and AGEs level. As the primary responsibility for glycation, the loss of Lysine (Lys) and Arginine (Arg) in MF with longer glycation time (>24 h) was more than 25%. While, the associated AGEs, including Nε‐carboxymethyl‐lysine (CML), Nε‐carboxyethyl‐lysine (CEL), and methylglyoxal‐derived hydroimidazolone 1 (MG‐H1), presented a gradually increasing tendency with glycation time. The kinetic studies indicated that the formation of CML and MG‐H1 presented a highly linear correlation with heating time, while the CEL development could be described as an exponential function of glycation time (r ≥ 0.95). Moreover, the correlation analysis among these chemical indicators indicated that colour development was positively correlated with AGEs (r ≥ 0.85), while negatively related to the loss of Lys and Arg (r ≤ −0.89). The findings may help to better control the glycation course of food protein based on the formation of AGEs. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) spectroscopy is one of the most powerful tools in analytical chemistry. An important step in the analysis of NMR data is the assignment of resonance frequencies to the corresponding atoms in the molecule being investigated. The traditional approach considers the spectrum's characteristic parameters: chemical shift values, internuclear couplings, and peak intensities. In this paper, we show how to support the process of assigning a series of spectra of similar organic compounds by using temperature coefficients, that is, the rates of change in chemical shift values associated with given changes in temperature. [ABSTRACT FROM AUTHOR]

Hydroxyl‐terminated polybutadiene (HTPB) is hydrogenated using catalytic hydrogenation with HTPB as a precursor using various catalysts. The hydrogenation is carried out using iso‐propyl alcohol (IPA) and toluene as an active solvent media. The present paper used (a) charcoal, (b) palladium supported by charcoal (Pd−C), (c) palladium supported by zirconium oxide (Pd‐ZrO2), and (d) copper chromite (CC) as catalysts for hydrogenation of HTPB to study the influence on the degree of hydrogenation with respect to each catalyst. The experimental data shows that hydrogenated HTPB (HHTPB) formation is predominantly controlled by physisorption and chemical reaction with a catalyst. Various techniques like NMR, FTIR and chemical analysis are used to characterize HTPB and HHTPB. Degree of hydrogenation of HTPB is found to be higher with copper chromite when compared to other catalysts in this work. Post‐hydrogenation, no significant change in hydroxyl value and a marginal increase in molecular weight is noticed with all catalysts. HTPB and HHTPB samples are analyzed using FTIR, 1H‐NMR, and 13C‐NMR and TG‐DSC studies, and inferences are derived with respect to the change in the olefinic region, microstructural changes, molecular weight, and thermal decomposition characteristics. [ABSTRACT FROM AUTHOR]

With the advent of energy crisis and stringent emission regulations, natural gas (NG)/diesel dual‐fuel engines have entered the popular view. In this paper, the accurate boundary conditions are determined by the Converge model and the transient parameters were introduced into the chemical kinetics model to make the operating conditions more closely match the actual engine operating conditions. The effects of different methane/n‐heptane ratios, initial temperatures, initial pressures, and equivalence ratios on the IDT of methane/n‐heptane fuel mixtures were analyzed using comprehensive chemical kinetic tools such as mole fraction analysis, ROP analysis, and sensitivity analysis. The IDT of methane/n‐heptane mixture decreased significantly with increasing the equivalence ratio, initial pressure, and the proportion of n‐heptane in the mixture, but the change of temperature was more complicated for the IDT. The NTC behavior of methane/n‐heptane mixture was also affected by the NTC behavior of n‐heptane. With the increase of initial temperature, the consumption of methane and n‐heptane appeared to be significantly accelerated. The peak of radicals and intermediate groups appeared earliest and had the highest radical concentration when the n‐heptane content was 30%. With the increase of initial pressure, the peak moments of the six radicals were further advanced, but the mole concentrations of O, OH, H radicals decreased significantly. This paper not only provides a reference for the design of NG/diesel dual‐fuel engines, but also provides a theoretical basis and data support for improving the ignition and initial condition setting strategies of the engines. [ABSTRACT FROM AUTHOR]

Raman spectroscopy can be effectively used for detection and analysis of chemical agents that are serious threats in modern warfare, but the detection and analysis performance is prone to deterioration due to noise. The existing denoising technique has limitations that there is no criterion for selecting the window length and that the filtering distorts the peaks, key features for Raman spectral data analysis. To overcome such limitations, in this paper, we propose the peak‐aware adaptive denoising for Raman spectroscopy based on machine learning approach. The proposed technique utilizes the information of detected peaks to eliminate noise effectively using different window values optimal for each region in the Raman spectrum while preserving the shape of peaks. We conducted the various analyses and experiments, and the proposed technique showed a 28% lower Euclidean distance and a 48% lower Fréchet inception distance compared to the existing technique, meaning the proposed technique outperformed the existing one. [ABSTRACT FROM AUTHOR]

Chemical analysis of glass from African archaeological sites has become a standard research tool over the past decades. Despite the multiplication of studies, the continent still exhibits vast unexplored regions. One of these is the surroundings of Lake Chad. This paper discusses the results of LA‐ICP‐MS analysis of recently excavated glass beads from the late medieval Chadian site of Tié. We demonstrate that the composition of those glass beads largely matches assemblages from along the East African coast. This indicates that most of the beads examined entered the region via a hitherto undocumented east–west Sudanic route linking Northeast Africa with Lake Chad. [ABSTRACT FROM AUTHOR]

The requirement to establish novel methods for visual detection is attracting attention in many application fields of analytical chemistry, such as, healthcare, environment, agriculture, and food. The research around subjects like "point‐of‐need", "hue recognition", "paper‐based sensor", "fluorescent sensor", etc. has been always aimed at the opportunity to manufacture convenient and fast‐response devices to be used by non‐specialists. It is possible to achieve economic rationality and technical simplicity for optical sensing toward target analytes through introduction of fluorescent semiconductor/carbon quantum dot (QD) and paper‐based substrates. In this Review, the mechanisms of anthropic visual recognition and fluorescent visual assays, characteristics of semiconductor/carbon QDs and ratiometric fluorescence test paper, and strategies of semiconductor/carbon QD‐based hue recognition are described. We cover latest progress in the development and application of point‐of‐need sensors for visual detection, which is based on a semiconductor/carbon quantum dot‐based hue recognition strategy generated by ratiometric fluorescence technology. [ABSTRACT FROM AUTHOR]

The Journal of the Chinese Chemical Society (JCCS) recently published an editorial expressing gratitude to its supporters and announcing its achievements in 2023. The journal saw a modest increase in its impact factor, published 7 regular issues and 5 special issues, and received submissions from 38 countries. The editorial also announced the winners of the 2023 Best Article Award and introduced the Highly Cited Paper Award. JCCS plans to release a special issue in August 2024 focusing on precise measurement in analytical chemistry and curates virtual issues highlighting recent research. The journal aims to improve the quality of submissions and the review process while facilitating communication in the field of chemistry. [Extracted from the article]

One of the most important purposes of theoretical chemists is to derive new, useful, and reliable equations to compute the well‐known parameters like hardness, polarizability, magnetizability, and electrophilicity providing enough hints for the reactivity analysis of the chemical systems. In the derivation of such equations, our research team widely considers the popular electronic structure rules like electronegativity equalization, maximum hardness, minimum polarizability, minimum magnetizability, and minimum electrophilicity principles. Recently, in the light of maximum entropy and minimum magnetizability principles, Kaya and Chattaraj (2021) presented a simple way to calculate their standard absolute entropies (S0298) based on molar diamagnetic susceptibilities (χm) of inorganic ionic systems. In the present paper, a new and useful molar diamagnetic susceptibility calculation method including the use of van der Waals constants (a and b) is introduced. Here, we named this method as Kaya–Şimşek approach. Through the relations between molar diamagnetic susceptibility and van der Waals constants, we can easily predict the magnetic susceptibility of molecules that their magnetic susceptibilities are unknown. The results of the equations derived are quite close to experimentally reported data. The analyses made proved that van der Waals constants can be considered as chemical reactivity descriptors. We propose that in stable states, van der Waals constants are minimized. The validity of minimum magnetizability principle is supported with solid evidences. [ABSTRACT FROM AUTHOR]

Archaeological evidence as well as textual sources leave no doubt about Alwa's (Alodia's) intense transcultural connections, further corroborated by understudied overseas glass bead imports found there. This paper presents results of an analysis of 23 glass beads from Soba, the most prosperous capital of medieval Nubia. Compositional analyses using laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) have identified glass belonging to a number of broad compositional groups. Three samples were made of soda lime low‐alumina glass produced in the Middle East (v‐Na‐Ca) and Egypt (m/v‐Na‐Ca). The remaining beads were made of two types of mineral–soda high‐alumina glass (m‐Na‐Al) North Indian in origin. The results of this study provide new evidence for the provenance and chronology of glass beads available in medieval Soba and Northeast Africa, and contribute new data to research on trade contacts of that time. [ABSTRACT FROM AUTHOR]

The exploration and analyses of chemical components in (extra‐)terrestrial geological materials (such as asteroids and meteorites) are insightful in modern research. Laser‐induced breakdown spectroscopy (LiBS) is a popular method for analyzing the chemical attributes of geologic samples—which scientists use to study and understand planetary bodies and their complex histories. In the literature, several machine learning models that produce high‐accuracy predictions have been proposed. In our work, we compared the performances of such models in predicting elemental abundances on a certain spectroscopic dataset. Models included partial least squares (PLS), extreme gradient boost machines (XGB), neural networks, and linear models. In our results, we showed how PLS and XGB are superior in terms of high predictive power, their ability to generalize, and their reasonably efficient runtimes. In addition, we proposed Ensemble models that aggregate predictions of top‐tier models and observed that they can be desirable. We intend to gain better understanding of how these models perform in predicting elemental compositions on specific spectrum (LIBS) datasets. In this paper, we compare several machine learning models to identify those who performed best in a specific spectroscopic datasets. The models investigated include partial least squares, Lasso regression, support vector regression, artificial and convolutional neural networks, and extreme gradient boosting machines. We then propose an Ensemble model aggregating the predictions of the top‐tier, models and we have found that it performs significantly well. [ABSTRACT FROM AUTHOR]

While fingerprints are a highly used means of identification, not every fingerprint left behind on a potential crime scene can be used for identification purposes. In some cases, the fingerprint may be smudged, partially preserved or overlapping with other prints hence distorting the ridge pattern and may therefore be not appropriate for identification. Further, fingermark residue yields a very low abundance of genetic material for DNA analysis. In such cases, the fingermark may be used to retrieve basic donor information such as sex. The focus of this paper was to assess the possibility of differentiating between the sexes of the donor of latent fingermarks. Analytical method was GC–MS analysis of the chemical compounds of latent fingermarks using 22 male and 22 female donors. Results showed 44 identified compounds. Two alcohols, octadecanol C18 and eicosanol C20, were found to show a difference that was statistically significant between male and female donors. There is also some evidence for the possibility of distinguishing sex of the fingermark donor based on the distribution of branched chain fatty acids, as free compounds or esterified in wax esters. [ABSTRACT FROM AUTHOR]

There are many products in the market advertised as masking agents used to overpower strong nuisance odors, such as in or around water resource recovery facilities, solid waste processing facilities, landfills, composting sites, and so forth. Very little is known about the chemical component of these masking agents because they are protected by trade secrets. This is a problem for the parties involved, as the process of choosing the most adequate agent for the particular odor source falls into guesswork. This paper demonstrates that it is possible to determine how effective the masking product would be before spending time and resources in trials. It proposes to show this by comparing the Weber–Fechner curves of the odor‐causing compounds known to be emitted at the facility with the curves from the potential masking agents prepared in the laboratory using an olfactometer. Several sensorial examples show that when the Weber–Fechner curves of the odorants and those of candidate masking agents are compared, it is possible to define the effectiveness of the masking agent tested. This is a novel use of the Weber–Fechner curves. The results show there is direct correlation between what is observed by a panel with real life odor samples subjected to incremental dilution and the Weber–Fechner odor intensity‐odor concentration curve interaction between the odorants involved. Future work characterizing additional potential masking compounds by Weber–Fechner accompanied by odor profiling with dynamic olfactometry should shed light on the definitive effectiveness of this method in predicting masking effects and discovering useful masking compounds. Practitioner Points: Weber–Fechner curves provide relationships between odorant concentration and odor intensity.Dynamic olfactometry, in which real‐life air samples are sensorially analyzed by the odor profile method after subsequent dilutions, shows that odor masking occurs.Analyzing the Weber–Fechner curves of the odorants present in the dynamic olfactometry test show the existing odorant interactions.It is possible to predict the extent of the masking of potential compounds by comparing Weber–Fechner curves of masking agents against odorants causing nuisance.This methodology could help avoid spending resources in masking field trials that may result in further exacerbating the affected public. [ABSTRACT FROM AUTHOR]

All‐solid‐state batteries (ASSBs) have been attracting attention as the next generation batteries. Despite the growing interest, there are still many challenges faced in the commercial use of ASSBs. One of the biggest issues is the internal resistance generated at the interface between solid electrolyte (SE) and electrode. Understanding the solid–solid interactions requires chemical analysis near the interface. Auger electron spectroscopy (AES) is a suitable surface analysis technique to determine the lithium chemical state with high spatial resolution. However, SEs are often sensitive to electron beam irradiation, and the chemical state of SEs is easily changed during measurement. Therefore, in this study, scanning Auger microprobe (SAM) incorporated into a multitechnique XPS system was used to evaluate the electron beam damage on a LiPON (lithium phosphorus oxynitride) surface, and then the optimal conditions for AES mapping were determined. Using the optimal conditions, lithium chemical maps from LiPON/LiCoO2 cross‐section were obtained. In this paper, the results of quantitative examination of electron beam damage on LiPON surface and lithium chemical mapping will be discussed. [ABSTRACT FROM AUTHOR]

Compositional analysis has proved to be a powerful tool for investigating the recycling of transparent glass in the Roman and Byzantine periods. This paper expands the focus further to explore the recycling of coloured and opaque glass in the Late Iron Age and Roman periods in Britain. A review of the findings to date, predominantly for beads and bangles, illustrates how a combination of methods is needed to identify when coloured glass has been recycled and altered in the past. Chemical analysis, microstructural examination and experimentation have been used to understand how coloured glass was mixed, diluted, and modified with novel colourants and opacifiers, in ways that are not apparent from non‐destructive chemical analysis alone. The paper discusses the possible types and sources of trade glass, the challenges of recycling mono‐ and polychrome glass in different colours, and the unconventional methods used by glassworkers on the periphery of Roman influence to extend and modify coloured glass to produce distinctive items in order to express their identity. [ABSTRACT FROM AUTHOR]

This document is a guest editorial introducing a special collection titled "Frontiers in Chemical Bonding and Aromaticity" in honor of Professor Miquel Solà's 60th birthday. The collection features over 30 papers contributed by Solà's former students, colleagues, and friends, showcasing his diverse passions in chemistry. The editorial provides a brief biography of Solà, highlighting his achievements and contributions to the field of theoretical and computational chemistry. The guest editors express their gratitude to the contributing authors and the editorial team for their support in bringing this collection to fruition. [Extracted from the article]

Thermochemical biorefineries for the production of chemicals and materials can play an important role in the bioeconomy. However, their economic viability is often questioned under the premise of the economy of scale. This paper presents a regional, modular biorefinery concept for the production of the platform chemicals hydroxymethylfurfural (HMF), furfural and phenols from the lignocellulosic perennial miscanthus, which can be cultivated on marginal and degraded areas. The paper focuses on the question of the minimum selling price of HMF and the optimal plant size for this purpose, using the region of Baden‐Württemberg, Germany, as an example. Based on small pilot plant results, a scalable process simulation was created via AspenPlus. This allows different scenarios and process combinations of this multi‐output biorefinery concept to be compared with each other. Using this, a minimum sales price for the main product HMF is calculated using methods of dynamic investment cost calculation according to the net present value method. Based on this, the plant capacity was scaled. The scenarios and sensitivity analyses show that, with an accuracy of ±15%, regional biorefineries could already offer platform chemicals at prices of 2.21–2.90 EUR/kg HMF at the current stage of development. This corresponds to three to four times the price of today's comparative fossil base chemicals and is thus a competitive option from the authors' point of view. The local biomass and the heat prices were identified as the main influencing factors. As a result, the selection of the location will have a decisive influence on the economic viability of such concepts in the case of further development and optimization of the process in first demonstration plants. [ABSTRACT FROM AUTHOR]

BACKGROUND: Consumer interest in safeguarding animal welfare and increased demand for fresh aquatic products support the need to understand the effects of stunning methods used in aquaculture on the biochemical process affecting fish fillet quality. The present paper aimed at comparing electrical stunning (ES) and cold shock (ICE) in Salmo carpio, an Italian endemic under‐investigated species. Rigor mortis evolution, fillet adenosine 5′‐triphosphate (ATP), shape, colour, pH and water holding capacity were assessed by integrating chemical and image analyses. RESULTS: Seventy‐two fish (24 fish per treatment) were stunned by ES, ICE or anaesthesia (AN, used as control), then percussively slaughtered. ES and ICE hastened rigor mortis onset and resolution (21 and 28 h post mortem) compared to AN. This was confirmed by the faster ATP degradation in ES and ICE. Fillet shape features varied during rigor mortis, according to the stunning method, with the perimeter showing irreversible variation in ES and ICE groups. Initial circularity was recovered only in AN, while ICE and ES fillets showed significantly different values, between 0 and 192 h. CONCLUSION: ES is a promising stunning technique for S. carpio, but parameters should be optimized, because of the adverse effect on muscle activity which caused a fast pH drop, and the presence of blood spots in the fillets. Further studies are needed to understand whether fillet shape changes can interfere with filleting or fillet processing and consumer appreciation. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Radix Cudramiae, known as "Chuan‐Po‐Shi" in China, is a herbal medicine widely used in the southwest of the country, especially applied by the Miao and Zhuang nationalities for the treatment of liver diseases, such as acute liver injury and liver fibrosis. As a kind of ethnomedicine, the report on its chemical analysis was still blank, which restricted its clinical application. Therefore, this paper aimed to illustrate the chemical characteristics of Radix Cudramiae. A rapid analytical strategy based on ultra‐high‐performance liquid chromatography coupled with quadrupole time‐of‐flight tandem mass spectrometry was developed to profile the natural small‐molecular compounds in Radix Cudramiae, as well as the related prototypes and their metabolites in rats after drug administration. As a result, a total of 74 compounds were detected in the aqueous exact of Radix Cudramiae. In vivo, 45 chemicals including 16 prototypes and 29 metabolites in rat serum, along with 35 chemicals including 17 prototypes and 18 metabolites in rat liver, were screened out and identified. For the first time, the chemical constituents of Radix Cudramiae and their metabolic characteristics were discovered. It was hoped that this work would be beneficial for the safe and effective application of Radix Cudramiae in a clinic. [ABSTRACT FROM AUTHOR]

The problem of reducing the amount of the analyzed sample and waste during chemical analysis has recently received special attention. In this paper, a method relating to adsorptive stripping voltammetry, using a carbon paste electrode modified with β‐Cyclodextrin were used for Allura Red AC determination in soft drinks. The redox behavior of the dye was studied using the developed sensor, and a mechanism for its oxidation was proposed. Under optimal analysis conditions, the instrumental range of determined concentrations is 0.16–4.9 μg/mL, and the LOQ is 0.21 μg/mL with an RSD below 10 %. The proposed methodology and developed sensor have been successfully applied to model solutions and soft drinks analysis. [ABSTRACT FROM AUTHOR]

This paper reports the chemical composition of 36 glass finds from Histria, Romania, mainly dated to the Late Antique period (4th–6th c. AD) obtained by Prompt Gamma Activation Analysis (PGAA) at the Budapest Neutron Centre (BNC). Histria glass fragments were identified as Série 2.1, Série 3.2, and Série 3.3 of Foy, HIMT, Roman, and Sb decolorized. Most of the analyzed objects were manufactured from glass originating in Egyptian primary workshops. These analytical results are an additional proof for the trade connection of Histria with the rest of the Roman Empire. [ABSTRACT FROM AUTHOR]

Recycling is increasingly visible in archaeological descriptions of technology. This has a range of benefits as we attempt to engage with the full complexity of the material past. However, this paper examines in more detail whether a singular focus on recycling is positive for archaeological science. It considers the historical relationship between recycling and the chemical analysis of early copper alloys, the constraints of the different conceptual and statistical techniques that can be employed, and broader ideas of metal mutability and the characterisation hypothesis. Overall, anything that widens our conceptual toolkit should be welcomed. However, it is most helpful to have recycling emerge from case study data as part of a broader approach, rather than to focus on it as a sole aim. Similarly, the prioritisation of provenance has sometimes not helped the field. Engaging with a wider 'characterisation hypothesis' would bring several benefits, and help build collaborations with other areas of archaeology. [ABSTRACT FROM AUTHOR]

This article is an overview of advances in Raman spectroscopy published in 2019 in the Journal of Raman Spectroscopy (JRS) and, in addition, trends over the past decade across journals that have published papers important to the field of Raman spectroscopy. The trends are based on statistical data of article counts obtained from Clarivate Analytic's Web of Science Core Collection by year and by subfield of Raman spectroscopy. Normally in this review, coverage would be provided for presentations involving Raman Spectroscopy at the following four international conferences previously scheduled for this year: the International Conference on Raman Spectroscopy (ICORS 2020) in Rome, Italy; SCIX 2020 organized by the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) in Reno, Nevada, USA, in October; the European Conference on Nonlinear Optical Spectroscopy (ECONOS 2020) in Karlsrue, Germany, in April; and the International Conference on the GeoRaman Spectroscopy (GeoRaman 2020) in Bilbao, Spain, in November (originally scheduled for Weihai, China, in June). Of these, the ICORS 2020 has been rescheduled for 2021 at the same location; ECONOS 2020 has been canceled, but instead, a special issue section is being organized by invitation to commemorate the passing of JRS Board member Marcus Motzkus; SCIX 2020 has been changed to a virtual online conference; GeoRaman 2020 has been canceled, but online submission of abstracts will be made available with selected invitations to submit papers for a special issue of JRS. Finally, papers published in JRS in 2019 are highlighted and arranged by topics at the frontier of Raman spectroscopy. Based on these data, presentations, and publications, it is clear that Raman spectroscopy continues as an expanding field of research across a wide range of novel disciplines and applications that provide sensitive photonic information at the molecular level. [ABSTRACT FROM AUTHOR]

Beta regression has become a popular tool for performing regression analysis on chemical, environmental, or biological data in which the dependent variable is restricted to the interval [0, 1]. For the first time, in this paper, we propose a Liu estimator for the beta regression model with fixed dispersion parameter that may be used in several realistic situations when the degree of correlation among the regressors differs. First, we show analytically that the new estimator outperforms the maximum likelihood estimator (MLE) using the mean square error (MSE) criteria. Second, using a 'simulation study, we investigate the properties in finite samples of six different suggested estimators of the shrinkage parameter and compare it with the MLE. The simulation results indicate that in the presence of multicollinearity, the Liu estimator outperforms the MLE uniformly. Finally, using an empirical application on chemical data, we show the benefit of the new approach to applied researchers. Beta regression is popular when the dependent variable is restricted to the interval [0, 1], such as rates and proportions. This paper suggests Liu estimators that may be used in the presence of multicollinearity. We show that the Liu estimator outperforms the MLE in a simulation study. Finally, using an empirical application on chemical data, we show the benefit of the new approach. [ABSTRACT FROM AUTHOR]

The consumption of design drugs, frequently known as new psychoactive substances (NPS), has increased considerably worldwide, becoming a severe issue for the responsible governmental agencies. These illicit substances can be defined as synthetic compounds produced in clandestine laboratories in order to act as analogs of schedule drugs mimetizing its chemical structure and improving its pharmacological effects while hampering the control and making regulation more complicated. In this way, the development of new methodologies for chemical analysis of NPS drugs is indispensable to determine a novel class of drugs arising from the underground market. Therefore, this work shows the use of high-resolution mass spectrometry Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) applying different ionization sources such as paper spray ionization (PSI) and electrospray ionization (ESI) in the evaluation of miscellaneous of seized drugs samples as blotter paper (n = 79) and tablet (n = 100). Also, an elucidative analysis was performed by ESI(+) MS/MS experiments, and fragmentation mechanisms were proposed to confirm the chemical structure of compounds identified. Besides, the results of ESI(+) and PSI(+)- FT-ICR MS were compared with those of GC--MS, revealing that ESI(+)MS showed greater detection efficiency among the methodologies employed in this study. Moreover, this study stands out as a guide for the chemical analysis of NPS drugs, highlighting the differences between the techniques of ESI(+)-FT-ICR MS, PSI(+)-FTI-CR MS, and GC--MS. [ABSTRACT FROM AUTHOR]

GeoPT, the proficiency test organised by the International Association of Geoanalysts (IAG), provides z‐scores that indicate a participant's performance on a scale expressing fitness for purpose. Analytical results are converted into z‐scores by using an "assigned value" and a standard deviation set by the IAG as a criterion of fitness for purpose. The assigned value is a consensus derived from the participants' results themselves, intended to be the best possible estimate of the true value that can be derived from the results and methodological information reported by the participants. In some instances where no assigned value is produced, a "provisional value" is made available. This paper discusses the different statistical ways in which an assigned value can be determined and concludes that as well as the judicious use of statistics, demonstrable expertise in the analytical chemistry and a detailed knowledge of the composition of the test materials are required in the assessment of assigned values. [ABSTRACT FROM AUTHOR]

This article is an overview of advances in Raman spectroscopy published in 2018 in the Journal of Raman Spectroscopy (JRS) and, in addition, trends over the past decade across journals that have published papers important to the field of Raman spectroscopy. The trends are based on statistical data of article counts obtained from Clarivate Analytic's Web of Science Core Collection by year and by subfield of Raman spectroscopy. Coverage is provided for presentations involving Raman spectroscopy at four international conferences this year: the Tenth International Conference on Advanced Vibrational Spectroscopy (ICAVS‐10) in Aukland, New Zealand in July; SCIX 2019 organized by the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) in Palm Springs, California USA in October; the European Conference on Nonlinear Optical Spectroscopy (ECONOS 2019) in Rouen, France in April; and the Tenth International Congress on the Application of Raman Spectroscopy in Art and Archaeology (RAA 2019) in Potsdam, Germany in September. Finally, papers published in JRS in 2018 are highlighted and arragned by topics at the frontier of Raman spectroscopy. Based on these data, presentations, and publications, it is clear that Raman spectroscopy continues as an expanding field of research across a wide range of novel disciplines and applications that provide sensitive photonic information at the molecular level. [ABSTRACT FROM AUTHOR]

Transfer learning (TL), the sub‐discipline of machine learning devoted to learning from different domains, has gained increasing attention over the past decade. With the current contribution, we aim at giving a concise overview on theory, concepts, and applications of TL from a chemometrician's perspective and draw some connections to previous work on calibration model updating/adaptation and calibration transfer. Furthermore, we provide a demonstration of the application of TL in analytical chemistry and discuss the benefits and challenges associate with its use for real‐world problems. We conclude the paper by discussing some open problems and by contemplating on future research directions. [ABSTRACT FROM AUTHOR]

This paper aims to apprehend evolution of ceramic manufacture strategy in the Johnston‐Vieillard manufactory (Bordeaux, France), which produced white earthenwares between 1835 and 1895. Glazes of fragments of 76 sherds, dated from different periods of the 19th century and found in excavations were characterised thanks to combined chemical and mechanical analysis. A comparative study was carried out for the determination of boron content in glazes by LA‐ICP‐MS and ion‐beam analyses (PIGE). In addition, an innovative study of the mechanical characteristics of the glazes by nanoindentation experiments was carried out in order to see whether or not the evolution of the glaze recipes was accompanied by an evolution of their mechanical properties. [ABSTRACT FROM AUTHOR]

Diberyllium complexes with ultrashort metal−metal distances (USMMDs, defined as dM−M<1.900 Å) are fascinating for the nature of the valence electronic structure of Be atoms. In this paper a family of diberyllium complexes [L−BeH3Be−L]+ (1–7), in which L was an N‐heterocyclic carbene (NHC) or a mesoionic carbene (MIC), were studied by Density Functional Theory (DFT) at the B3LYP/cc‐pVTZ level. It was found that complexes 1–7 possessed ultrashort Be−Be distances of 1.754 Å–1.779 Å and strong covalent bonds between a Be atom and its adjacent carbene center (Ccarb) at once. Electronic structures and chemical bonding analyses ascribed USMMDs between the Be atoms to the Be−H−Be three‐center two‐electron (3c‐2e) bonds. The strong Be−Ccarb bonds were determined by combining effects of covalent interaction and electrostatic interaction between the Be and the Ccarb atoms. These complexes exhibited a great stability with large highest occupied molecular orbital‐lowest unoccupied molecular orbital (HOMO‐LUMO) gaps, high vertical detachment energies (VDEs) and low vertical electron affinities (VEAs) and are potential targets in future experiments. [ABSTRACT FROM AUTHOR]

New psychoactive substances (NPS) are a wide group of compounds that try to mimic the effects produced by the 'classical' illicit drugs, including cannabis (synthetic cannabinoids), cocaine and amphetamines (synthetic cathinones) or heroin (synthetic opioids), and which health effects are still unknown for most of them. Nowadays, more than 700 compounds are being monitored by official organisms, some of which have been recently identified in seizures and/or intoxication cases. Toxicological analysis plays a pivotal role in NPS research. A comprehensive investigation on NPS, from the first identification of a novel substance until its detection in drug users to help in diagnostics and medical treatment, requires the use of a wide variety of instruments and analytical strategies. This paper illustrates the key role of mass spectrometry (MS) along a comprehensive investigation on NPS. The synthetic cannabinoid XLR‐11 and the synthetic cathinone 5‐PPDi have been chosen as representative substances of the most consumed NPS families. Moreover, both compounds have been investigated at our laboratory in different stages of the three‐step strategy considered in this article. The initial identification and characterisation of the compound in consumption products, the first reported metabolic pathway and the development of analytical methodologies for its determination (and/or their metabolites) in different toxicological samples are described. The analytical strategies and MS instruments are briefly discussed to show the reader the possibilities that MS instrumentation offer to analytical scientists. This publication aims to be a starting point for those interested on the NPS research field from an analytical chemistry point of view. [ABSTRACT FROM AUTHOR]

The paper proposes a methodology based on near‐infrared (NIR) spectrometry for studying stratigraphy and depth profiles in archaeological excavations. The NIR spectra can be used to describe and complement the wet chemical analysis. Soil samples were collected from a 0.8 m deep stratigraphy of a Neolithic site that were analyzed by three different NIR instrumentations. Phosphate‐ and magnetic susceptibility and inductively‐coupled plasma mass spectrometry measurements were also conducted as reference analysis. Principal component analysis on the data from three different NIR instrumentations gave useful score plots that allowed grouping of the samples. The results from the lab spectrometer were most useful, although the hyperspectral NIR camera was the fastest method to obtain spectra of many samples from one image. The paper shows how the NIR spectral data can be used for multivariate analysis to get meaningful conclusions on archaeological soils and sediments, especially in terms of understanding site development/phases and soil formation. [ABSTRACT FROM AUTHOR]

This annual review is an overview of advances in the field of Raman spectroscopy as found in papers published in the previous calendar year in the Journal of Raman Spectroscopy (JRS), as well as in trends over the past decade across journals that have published papers important to the field of Raman spectroscopy. This information is gleaned from statistical data on article counts obtained from the Clarivate Analytic's Web of Science Core Collection by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations at the XXVI International Conference on Raman Spectroscopy (ICORS 2018) in Jeju Island, Korea in August 2018, and contributions on Raman scattering at SCIX 2018, organized by the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) in Atlanta, Georgia, USA in October 2018. Coverage is also provided for topics from the European Conference on Nonlinear Optical Spetroscopy (ECONOS 2018) held in April in Milan, Italy and GeoRaman 2018 in Catania, Italy in June. Finally, papers published in JRS in 2017 are highlighted and arranged by topics at the frontier of Raman spectroscopy. On the basis of this survey information, it is clear that Raman spectroscopy continues as in recent years as a rapidly expanding field of research across a wide range of novel disciplines and applications that provide sensitive photonic information of matter at the molecular level. A review is presented of the current status of the field of Raman spectroscopy for the past 10 years, symposia at ICORS 2018 in Korea and SCIX 2018 in Georgia and papers published in the Journal of Raman Spectroscopy during the calendar year 2017. This is part XII of an annual review of Raman spectroscopy covering: SERS, Biosciences, Nanomaterials, Nonlinear and Time‐Resolved, Resonance, Art and Archaeology, Solid‐State, Liquids, Solutions, Gases, Pharmaceuticals, Forensics, High Pressure, Vibrational Analysis, Special Techniques, and Reviews. [ABSTRACT FROM AUTHOR]

This memorial issue is a collection of papers that showcase the diverse research interests of the late Professor King‐Chuen Lin (1953 – 2022) in the fields of physical chemistry, analytical chemistry, biophysics, and material chemistry. These papers have been contributed by Prof. Lin's friends, colleagues, and former group members. The global chemistry community deeply mourns the loss of Prof. Lin, and through this special issue, the invited contributors aim to honor his memory. [ABSTRACT FROM AUTHOR]

This paper describes a laboratory course that introduces basic crystallographic data analysis to chemistry students encountering for the first time the world of crystals and crystal structures. The aim of the course is to provide students with direct contact with crystal structures and hands‐on experience in structure analysis. To this end, a set of appropriately simple inorganic molecular structures was selected, consisting of salts of hexaaqua metal ions with organic counter‐ions. By exploiting the crystallographic tools available in the Cambridge Structural Database program Mercury, students learn how to visualize and analyse a set of atomic coordinates. In this way they learn how to extract bonding and structural information concerning intramolecular interactions in both salt components. Intermolecular interactions are next analysed by looking closely at supramolecular motifs and packing patterns generated by hydrogen bonds. This pragmatic approach turned out to be effective and extremely useful for summarizing many chemical concepts learned by students during a bachelor degree course in chemistry. The experience provides at the same time some basic capabilities for properly managing crystal structure analysis. [ABSTRACT FROM AUTHOR]

For the application of surface acoustic wave sensors at high temperatures, both a high‐temperature stable piezoelectric substrate and a suitable metallization for the electrodes are needed. Our current attempt is to use TiAl thin films as metallization because this material is also known to be high temperature stable. In this study, Ti/Al multilayers and Ti‐Al alloy layers were prepared in combination with an SiO2 cover layer or a W barrier layer at the interface to the substrate (thermally oxidized Si or Ca3TaGa3Si2O14) as an oxidation protection. To form the high‐temperature stable γ‐TiAl phase and to test the thermal stability of the layer systems, thermal treatments were done in vacuum at several temperatures. We used X‐ray photoelectron spectroscopy (XPS) sputter depth‐profiling to investigate the film composition and oxidation behavior. In this paper, we demonstrate how the semiautomatic peak fitting can help to extract beside the elemental information also the chemical information from the measured depth profiles. [ABSTRACT FROM AUTHOR]

In this paper, the grain refining performance of Al‐5Ti‐1B master alloy on the recycled A356 alloy is investigated using the macrostructure examination and chemical analysis. Results show that Al‐5Ti‐1B is composed of the dispersion of blocky TiAl3 particles and mixtures of small TiAl3 and TiB2 particles. Both particles refine grain structures of A356 alloy. As the initial recycling process proceeds, A356 alloy still exhibits fine structures. However, during the subsequent recycling process, the grain size of A356 alloy become larger. The concentration of titanium and boron decreases with increasing the number of recycling, especially in the subsequent recycling process. It is proposed that recycling of refined A356 can best be conducted in the initial recycling process and then additional grain refiner needs to be added to maintain the grain refining performance for the continuous recycling process of A356 alloy. [ABSTRACT FROM AUTHOR]

Tandem mass spectrometry involves isolation of specific precursor ions and their subsequent excitation through collision‐, photon‐, or electron‐mediated activation techniques in order to induce unimolecular dissociation leading to formation of fragment ions. These powerful ion activation techniques, typically used in between mass selection and mass analysis steps for structural elucidation, have not only found a wide variety of analytical applications in chemistry and biology, but they have also been used to study the fundamental properties of ions in the gas phase. In this tutorial paper, a brief overview is presented of the theories that have been used to describe the activation of ions and their subsequent unimolecular dissociation. Acronyms of the presented techniques include CID, PQD, HCD, SORI, SID, BIRD, IRMPD, UVPD, EPD, ECD, EDD, ETD, and EID. The fundamental principles of these techniques are discussed in the context of their implementation on ultra‐high resolution tandem mass spectrometers. © 2020 John Wiley & Sons Ltd. Mass Spec Rev [ABSTRACT FROM AUTHOR]

Purpose/objectives: To provide an order of magnitude estimate of the minimum dose rate (Rmin) required by pulsed ultra‐high dose rate radiotherapy (FLASH RT) using dimensional analysis. Materials/methods: In this study, we postulate that radiation‐induced transient hypoxia inside normal tissue cells during FLASH RT results in better normal tissue sparing over conventional dose rate radiotherapy. We divide the process of cell irradiation by an ultra‐short radiation pulse into three sequential phases: (a) The radiation pulse interacts with the normal tissue cells and produces radiation‐induced species. (b) The radiation‐induced species react with oxygen molecules and reduce the cell environmental oxygen concentration (O2). (c) Oxygen molecules, from nearest capillaries, diffuse slowly back into the resulted low O2 regions. By balancing the radiation‐induced oxygen depletion in phase II and diffusion‐resulted O2 replenishment in phase III, we can estimate the maximum allowed pulse repetition interval to produce a pulse‐to‐pulse superimposed O2 reduction against the baseline O2. If we impose a threshold in radiosensitivity reduction to achieve clinically observable radiotherapy oxygen effect and combine the processes mentioned above, we could estimate the Rmin required for pulsed FLASH RT through dimensional analysis. Results: The estimated Rmin required for pulsed FLASH RT is proportional to the product of the oxygen diffusion coefficient and O2 inside the cell, and inversely proportional to the product of the square of the oxygen diffusion distance and the drop of intracellular O2 per unit radiation dose. Under typical conditions, our estimation matches the order of magnitude with the dose rates observed in the recent FLASH RT experiments. Conclusions: The Rmin introduced in this paper can be useful when designing a FLASH RT system. Additionally, our analysis of the chemical and physical processes may provide some insights into the FLASH RT mechanism. [ABSTRACT FROM AUTHOR]

The attachment mode of arc on anode is closely related to the non‐equilibrium chemical kinetics process of the anode region of arc. In this paper, the detailed chemical reaction mechanisms in the flow‐affected region for both diffuse and constricted argon arc attachments are investigated by means of one‐dimensional discharge coupled with a single‐fluid, two‐temperature model. The collisional‐radiative model is used to examine the chemical reaction processes occurring in the anode region, including the arc centreline and fringe region. The numerical results are validated by comparison with available experimental data. The obtained radial distributions of electron temperature, electron density, excited states densities, ionization, and recombination processes reveal that different mechanisms dominate the diffuse and constricted arc‐anode attachments. [ABSTRACT FROM AUTHOR]

The International Consortium for Innovation & Quality (IQ) in Pharmaceutical Development recently established a working group focused on the development of a guidance to address Deuterated Active Pharmaceutical Ingredients. Deuteration of an Active Pharmaceutical Ingredient (API) in some cases can retard and/or alter API metabolism by exploiting the primary kinetic isotope effect. Several deuterated APIs have entered into the clinic, and one has recently been approved. In most cases, it is very difficult to nearly impossible to synthesize a 100% isotopically pure compound. This raises synthetic, analytical, and regulatory questions that warrant a science‐based assessment and recommendations for synthetic methods, analytical methods, and specifications. A cross functional team of scientists with expertise in isotope chemistry, process chemistry, analytical chemistry, and drug metabolism and pharmacokinetics have been meeting under the auspices of IQ to define and address these questions. This paper strives to frame chemistry, manufacturing, and controls challenges. [ABSTRACT FROM AUTHOR]

This paper presents a detailed elemental analysis of 64 glass beads and pendants dated to the Meroitic period (first–third centuries ad) and the Nobadian period (fourth–sixth centuries) from burial sites in the Lower Nubian Nile Valley region. Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) was used to determine the chemical composition of the glass and to gain knowledge about its origin. Four main glass types were identified: low‐alumina soda‐lime glass, high‐alumina glass, plant‐ash soda‐lime glass, and mixed‐alkali glass. Mineral soda‐lime glass (m‐Na‐Ca) of East Mediterranean/Egyptian provenance is dominant within the low‐alumina glass group from Meroitic and Nobadian periods. Mineral soda high‐alumina glass (m‐Na‐Al) appeared in the Nobadian bead assemblages, and the m‐Na‐Al 1 subtype was produced in Sri Lanka/South India. An initial insight into the origin of the glass beads in Nubia from the first to sixth centuries is described, indicating the first evidence for the presence of Asian objects in Nubia. The data obtained for the bead trade in North‐east Africa in this study has allowed a new light to be shed on the westward flow of Asian glass during a time of intensive maritime trade contacts with the wider Indian Ocean world. [ABSTRACT FROM AUTHOR]

In natural growth habitats, plants face constant, unpredictable changes in light conditions. To avoid damage to the photosynthetic apparatus on thylakoid membranes in chloroplasts, and to avoid wasteful reactions, it is crucial to maintain a redox balance both within the components of photosynthetic electron transfer chain and between the light reactions and stromal carbon metabolism under fluctuating light conditions. This requires coordinated function of the photoprotective and regulatory mechanisms, such as non‐photochemical quenching (NPQ) and reversible redistribution of excitation energy between photosystem II (PSII) and photosystem I (PSI). In this paper, we show that the NADPH‐dependent chloroplast thioredoxin system (NTRC) is involved in the control of the activation of these mechanisms. In plants with altered NTRC content, the strict correlation between lumenal pH and NPQ is partially lost. We propose that NTRC contributes to downregulation of a slow‐relaxing constituent of NPQ, whose induction is independent of lumenal acidification. Additionally, overexpression of NTRC enhances the ability to adjust the excitation balance between PSII and PSI, and improves the ability to oxidize the electron transfer chain during changes in light conditions. Thiol regulation allows coupling of the electron transfer chain to the stromal redox state during these changes. [ABSTRACT FROM AUTHOR]

Summary: Sustainable agriculture practices are often hampered by the prohibitive costs associated with the generation of fine‐resolution soil maps. Recently, several papers have been published highlighting how visible and near infrared (vis–NIR) reflectance spectroscopy may offer an alternative to address this problem by increasing the density of soil sampling and by reducing the number of conventional laboratory analyses needed. However, for farm‐scale soil mapping, previous studies rarely focused on sample optimization for the calibration of vis–NIR models or on robust modelling of the spatial variation of soil properties predicted by vis–NIR spectroscopy. In the present study, we used soil vis–NIR spectroscopy models optimized in terms of both number of calibration samples and accuracy for high‐resolution robust farm‐scale soil mapping and addressed some of the most common pitfalls identified in previous research. We collected 910 samples from 458 locations at two depths (A, 0–0.20 m; B, 0.80–1.0 m) in the state of São Paulo, Brazil. All soil samples were analysed by conventional methods and scanned in the vis–NIR spectral range. With the vis–NIR spectra only, we inferred statistically the optimal set size and the best samples with which to calibrate vis–NIR models. The calibrated vis–NIR models were validated and used to predict soil properties for the rest of the samples. The prediction error of the spectroscopic model was propagated through the spatial analysis, in which robust block kriging was used to predict particle‐size fractions and exchangeable calcium content for each depth. The results indicated that statistical selection of the calibration samples based on vis–NIR spectra considerably decreased the need for conventional chemical analysis for a given level of mapping accuracy. The methods tested in this research were developed and implemented using open‐source software. All codes and data are provided for reproducible research purposes. Highlights: Vis–NIR spectroscopy enables an increase in sampling density with little additional cost.Guided selection of vis–NIR calibration samples reduced the need for conventional soil analysis.Error of spectroscopic model prediction was propagated by spatial analysis.Maps from the vis–NIR augmented dataset were almost as accurate as those from conventional soil analysis. [ABSTRACT FROM AUTHOR]

Selected current trends in analytical chemistry are discussed and traced back to original work published more than a hundred years ago in the same field. Gravimetric microanalysis has been transformed into a mass‐sensitive sensor technology. New developments in molecular spectroscopy are seen in Raman spectroscopy. In the area of chemical sensors, paper‐based devices with visual readout (dipsticks, microfluidic pads) celebrate a revival. In "green" applications, the separation of analytes from complicated matrices is often the key to successful analysis. Continuous separation techniques are essential for the 24/7 production of goods with certified quality. Finally, micro‐ and nanoscale techniques rely on highly selective receptors, and their development is based on detailed understanding of the structure of ligand–receptor complexes. Back to the future: Selected current developments in analytical chemistry are discussed in this Viewpoint and traced back to original work published up to 150 years ago. Discussed topics include selective mass determination, molecular spectroscopy, chemical sensors, separation methods, and bioinspired receptors such as antibodies. [ABSTRACT FROM AUTHOR]