In the present study, 334 samples of mussels (Mytilus galloprovincialis) harvested along the coasts of the Central Adriatic Sea during the years 2020–2021 were analyzed for the presence of lipophilic marine biotoxins according to the European Harmonized Standard Operating Procedure. The results showed that 74 (22%) and 84 (25%) samples were positive to okadaic acid and yessotoxin groups, respectively. Among them, only 11 (3.3%) samples resulted as non-compliant, as they exceeded the maximum limits (160 μg okadaic acid equivalent/kg) established by the Regulation (EC) 853/2004. The method applied in this study was able to detect and quantify lipophilic marine biotoxins concentrations, in order to monitor their presence in molluscs and avoid the risk of consumer exposure.

The determination of isotope ratios in individual uranium particles is very important for nuclear safeguards. In this work, accelerator mass spectrometry (AMS), thermal ionization mass spectrometry (TIMS) and secondary ion mass spectrometry (SIMS) were applied to isotope ratio analysis of individual uranium particles and compared in terms of background, measurement accuracy and efficiency. Several individual uranium particles (1−7 μm) from certified reference materials were used as samples. The results show that the average values of blank counting rate of 235U for AMS, FT-TIMS (FT: fission track), SEM-TIMS (SEM: scanning electron microscope) and SIMS were 7.3, 7.8, 2.7 and 2.2 cps, respectively. The relative error of 234U/235U and 234U/236U isotope ratios of the particles from U200 for AMS were within 10% and 20%, whereas the results of FT-TIMS and SIMS were within 5% and 10%, respectively. The relative error and external precision of 234U/238U and 235U/238U of the particles from U850 for the method of AMS, SEM-TIMS and SIMS were within 10% and 5%, respectively. For 236U/238U, the average values of the relative error and external precision measured by AMS were within 5%, which measured by SEM-TIMS and SIMS were all within 10%. AMS has advantages in measuring 236U/238U. The measurement time of AMS and SEM-TIMS was shorter than that of FT-TIMS and longer than that of SIMS. It is considered that AMS and SEM-TIMS have a certain development prospect, and it is necessary to research deeply.

In a broader scenario, the forced degradation studies provided by the ICH guidelines for Q1A, Q1B, and Q2B degradation studies allow to know the CQA of the molecule used as a drug product, to determine the appropriate analytical methods, excipients, and storage conditions ensuring the quality of the drug, its efficacy, and patient safety. In this study, we focused our attention on understanding how oxidative stress is performed by H2O2-impacted small synthetic peptides that do not contain residues susceptible to oxidation such as methionine. Among the amino acids susceptible to oxidation, methionine is the most reactive and depending on the structure of the protein where it is exposed, it tends to oxidize by converting into methionine sulfone or methionine sulfoxide by oxidation of its sulfur atom. Scouting experiments obtained by forced oxidative stress conditions are presented on two small synthetic peptides that do not contain any methionine residues spiked with different amounts of H2O2, and they are analyzed by LC–MS/MS. Less frequent oxidation products than those commonly observed on proteins/peptides-containing methionine have been characterized on both peptides. The study demonstrated that somatostatin, by means of one residue of tryptophan on the molecule, can generate traces of several oxidized products detected by UPLC–MS. Furthermore, even at a negligible level, oxidation on tyrosine and proline in cetrorelix that does not contain methionine nor tryptophan has been detected by UHPLC–MS/MS. Identification and quantification of oxidized species were achieved by high-resolution MS and MS/MS experiments. Thus, FDSs undoubtedly aid the evaluation of the CQAs as an important component of the characterization package as recommended by HAs and ICH, facilitating the understanding of unforeseen features of the studied molecule used as drugs.

A pyrolyzer gas chromatography/mass spectrometry (GC/MS) method eliminates toxic solvents that burden our environment and can address the crucial problem of the solvent extraction GC/MS method. The purpose of this study is to establish an efficient quantitative analysis method for 10 phthalates that are regulated by the several governments. A change of concentrations over time for phthalates and internal standards was measured to verify the feasibility of using an auto sampler that facilitates analyzing multiple samples. Both standards maintained constant concentrations over the appropriate time for analysis. A certified reference material under the auspices of the Korea Research Institute of Standards and Science was used to verify the calibration curve obtained by the pyrolyzer GC/MS method, and a deviation was considered similar to the solvent extraction GC/MS method. Then the limit of detection and limit of quantitation values were confirmed for various consumer products. To verify the reliability of the method, a comparative test with several accredited testing institutes was conducted, and the results were within the standard deviations of the results provided by the institutes. These results indicate that the pyrolyzer GC/MS method can be used in not only screening but also in accurate quantitative analysis.

Quantitative proteomics is one of the most widespread applications of mass spectrometry. We have planned a series of short tutorials to help orient PhD students and young post-docs mostly focused on label-free experiments. This is not designed to be a comprehensive textbook, but an open-ended series discussing diverse issues. In this first tutorial we summarize major aspects of study design. In the second, we will discuss MaxQuant, a widely used software for evaluating LC-MS data in terms of protein abundances. The following two issues will deal with selecting proteins which can be reasonably quantified in an experiment, and how to deal with the often-missing values in protein abundance tables. The first step before designing an experiment is to determine the concept of the project. We must decide very clearly on what the objective is, and subsequently what questions need to be asked and what kind of answers we expect. Only after this can we design the experiments comprehensively. This might seem trivial, but incorrectly formulated experimental questions may lead to erroneous inferences, or to much lower impact and significance than hoped for. After conceptualizing the project, several things must be thoroughly examined regarding the experimental questions before further planning can commence. First, our questions should be testable and the experiments to be performed should be selected accordingly, for example, it must be decided if relative or absolute quantitation is required. Second, they should be defined before doing any experimental work. This is crucial to avoid false positives, for example, to employ FDR control correctly when performing multiple statistical tests. Third, response variables (typically protein abundances) should be reliably measurable, for example, their abundances should be over the limit of quantitation. Finally, it must be assessed whether we are focusing on the correct explanatory variables. This is especially important to avoid mistaking correlation for causality, for example, the age of patients should be considered when risk factors are evaluated. Having established the concept of the study, the next phase is experimental design. This involves extensive planning of every aspect from how to select samples, what kind of experiments should be performed, and what type of data analysis should be done. This is a major undertaking requiring a significant amount of time and effort, which usually requires preliminary experiments as well. Experimental design may be broadly divided into three categories: Medical aspects Determining adequate target and control groups depending on the objective of the project needs to be carefully considered.1, 2 Determining which individuals or samples should be included (or excluded) is also critical for the success of medical studies. First, only those should be included in a trial, whose condition does not interfere with the objective of the study (e.g., a patient may have multiple diseases at the same time, and the effects cannot be separated). Second, the groups studied should be homogenized with a number of parameters in mind. Most important among these are age, sex, and disease stage. Other parameters may also be used to select homogenous groups of subjects, for example, individuals with only a single illness, or non-smokers, or people with no prior medication taken. Beside scientific, often there are practical limitations as well (e.g., when only few individuals are available with a given medical condition). Having finished a study, it may be necessary to exclude a few individuals in the data evaluation stage (e.g., if there was a failure in the analytical system). Such exclusion criteria should always be defined before starting the study. All of these aspects require careful planning to minimize potential biases originating from sample selection. Since subjects of medical research are in most cases animals or humans, besides scientific, ethical concerns must be considered as well. This requires a detailed study protocol, summarizing scientific and ethical issues. Studies involving humans always (animal studies sometimes) require approval from the relevant authorities, typically the ethical committee of a hospital or the National Health Service (of the country where the research is taking place). The study protocol is a written record prepared before the initiation of study and must encompass in detail the description of the topic to be studied; ethical concerns; trial procedures; inclusion and exclusion criteria for the subjects included; and details of the decision making process. The study protocol should also include the potential benefits of the successful study, the number of patients to be included, planned interventions and their safety (if there is any, e.g., drawing blood), study design, the time interval of the study (including follow up time, e.g., until death, progression of the disease, or relapse), and the projected time until the final report (in most cases publication). Furthermore, before the initiation of any medical trial, participants should receive detailed information about the study including risks and procedures. They should also give written consent that they are willing to take part in the study voluntarily (informed consent). Study size The number of samples or studied individuals in a research project may vary in a wide range from only a handful to hundreds or even thousands. For example, verifying the efficiency of a protease may be achieved by analyzing only a small number of samples, while the characterization of differences in plasma protein levels in the case of two cancer types requires much more. Based on the number of samples, studies are usually separated into three groups: In a preliminary study, the aim is to develop and test experimental methods or research protocols and get preliminary information on samples to be studied in a later stage. Typically, only few samples are analyzed. These studies are also useful for supporting project proposals for more extensive studies. Preliminary studies are occasionally publishable if novel samples of methodologies are used. A pilot study is exploratory in nature. It is primarily used to characterize effect sizes (the standardized difference) between group means. Although analyzing more samples improves statistical power (the probability of obtaining true positive results), it also requires more effort (time and cost). In practice there is usually a compromise between these; ideally a pilot study should include 10, 15, or 25 samples per group if effect sizes are large, medium, or small, respectively.3 Because effect sizes are usually not known beforehand, they need to be approximated based on prior knowledge of the sample or species under investigation. Pilot studies are often sufficient to point research in novel directions and to push back frontiers of our knowledge. Most publications using quantitative proteomics are pilot studies and are within the range of the financial power of universities and academia. Their major limitation lies in medical research, primarily due to their inability to account for the heterogeneity of human population. Full-scale studies are always preceded by a pilot study and are usually more focused (e.g., on a few proteins or peptides of interest). In this case, effect sizes for the compounds of interest can be estimated based on the pilot study, hence necessary sample sizes can be calculated in advance.2 Full-scale studies that include hundreds or even thousands of samples or individuals have the advantage of representing the studied population better, and they are also suitable to identify small differences between groups. On the other hand, they require enormous amounts of resources, and extensive planning. Full-scale studies are necessary for medical applications, and are often commercially supported. 3. Planning analytical experiments and data evaluation strategies The experimental and technical design of a study involves careful planning of the sample preparation, analysis, data handling, and statistical analysis. First, it has to be decided if mass spectrometry based proteomics is the best experimental approach. For this, the possibilities and limitations of MS-based quantitative proteomics need to be understood. It is most frequently based on the measurement of LC-MS peak intensities or areas; however, this can be affected by several factors apart from analyte concentrations, for example, matrix effects, instrument parameters, and differences in ionization efficiencies. Because of these, there are two fundamental approaches to quantitation: relative and absolute quantitation. In relative quantitation two (or more) samples are compared to each other to determine the ratio of different analytes between them, which can be done with the use of stable isotope labeling (chemical, proteolytic, or metabolic labeling) or without it (label-free quantitation). On the other hand, in absolute quantitation protein concentrations (e.g., the concentration of an antibody species in human plasma) can be determined for individual samples with the help of stable isotope labeled internal standards. Although labeling-based strategies (both for relative and absolute quantitation) are more accurate and reproducible than label-free quantitation, they are more expensive, labor-intensive, and not applicable in every circumstance (e.g., for the analysis of human tissue samples). As for the majority of scientific projects that require quantitative proteomics label-free quantitation is sufficient, it is the method of choice in most cases. There is a multitude of experimental methods used in proteomics (sample preparation, HPLC-MS analysis, and data handling);4, 5 selecting and optimizing these is the main task of the analytical chemist. Discussing, or even listing these is out of the scope of this tutorial. Although the method of choice influences the planning process, there are universal concepts needed to be taken into account. The most important parts are the testing of the suitability of the system6—usually through preliminary studies; the randomization of sample preparation and analysis steps7—helping to reduce batch effects; and the implementation of experimental controls,8 which then can be used to monitor the state of the system during the experiments. The latter is especially important to track and minimize unwanted variations introduced into the data during the different steps of the analysis. For example, one may add standards (exogenous proteins or peptides) to the samples to monitor experimental errors, and use quality control samples to show system integrity. Data analysis and statistical methods used can also be tested for robustness via sensitivity analyses, which can provide information on how much the results are affected by the use of different methods. This is becoming more and more important in light of the large number of emerging data analysis solutions available.9 Designing and thoroughly planning a scientific project is an essential part of any project. Incorrectly formulated experimental questions or inadequately planned experiments can make the conclusions of the study invalid regardless of how well other aspects have been executed. Therefore, we recommend investing considerable time and effort into thoroughly planning every part of a project, and revising it several times before its initiation. This short tutorial is by no means comprehensive, but can serve as a starting point or a sort of guidebook summarizing the most important aspects to be considered before starting any experimental work.

Biglycan (BGN), a small leucine-rich repeat proteoglycan, is involved in a variety of pathological processes including malignant transformation, for which the upregulation of BGN was found related to cancer cell invasiveness. Because the functions of BGN are mediated by its chondroitin/dermatan sulfate (CS/DS) chains through the sulfates, the determination of CS/DS structure and sulfation pattern is of major importance. In this study, we have implemented an advanced glycomics method based on ion mobility separation (IMS) mass spectrometry (MS) and tandem MS (MS/MS) to characterize the CS disaccharide domains in BGN. The high separation efficiency and sensitivity of this technique allowed the discrimination of five distinct CS disaccharide motifs, of which four irregulated in their sulfation pattern. For the first time, trisulfated unsaturated and bisulfated saturated disaccharides were found in BGN, the latter species documenting the non-reducing end of the chains. The structural investigation by IMS MS/MS disclosed that in one or both of the CS/DS chains, the non-reducing end is 3-O-sulfated GlcA in a rather rare bisulfated motif having the structure 3-O-sulfated GlcA-4-O-sulfated GalNAc. Considering the role played by BGN in cancer cell spreading, the influence on this process of the newly identified sequences will be investigated in the future.

Boehmeria rugulosa Wedd. is an evergreen tree of Urticaceae family. Its bark has been extensively used in ethno-medicinal system for various ailments such as bone fracture, sprain, snakebite, and wound healing. Phyto-metabolites, which are considered as the principle components for biological activities, have been least explored for this plant. The present work investigated metabolite profiling of the stem bark of B. rugulosa in water extract using Ultra Performance Liquid Chromatography Quadrupole Time of Flight Mass Spectrometry (UPLC-QToF-MS) technique coupled with the UNIFI platform. We identified, for the first time, 20 polyphenolic metabolites belonging to seven groups: caffeoylquinic acids, coumaroylquinic acids, flavan-3-ols, oligomeric flavonoids, caffeic acid derivatives, coumaric acid derivative, and flavone glycoside in the B. rugulosa extract. UNIFI informatics-coupled UPLC-QToF-MS platform aids in the quick identification and fragmentation pattern of metabolites, with higher degree of reproducibility. The present study provides a chemical and therapeutic basis for further exploration of B. rugulosa as a valuable source of phytochemicals that could be instrumental in deciphering its ethno-medicinal utility for various human diseases.

This study employed a vacuum ultraviolet synchrotron radiation source and reflectron time-of-flight mass spectrometry (TOF-MS) to investigate the photoionization and dissociation of styrene. By analyzing the photoionization mass spectrum and efficiency curve alongside G3B3 theoretical calculations, we determined the ionization energy of the molecular ion, appearance energy of fragment ions, and relevant dissociation pathways. The major ion peaks observed in the photoionization mass spectra of styrene correspond to C8H8+, C8H7+ and C6H6+. The ionization energy of styrene is measured as 8.46 ± 0.03 eV, whereas the appearance energies of C8H7+ and C6H6+ are found to be 12.42 ± 0.03 and 12.22 ± 0.03 eV, respectively, in agreement with theoretical values. The main channel for the photodissociation of styrene molecular ions is the formation of benzene ions, whereas the dissociation channel that loses hydrogen atoms is the secondary channel. Based on the experimental results and empirical formulas, the required dissociation energies (Ed) of C8H7+, C8H6+ and C6H6+ are calculated to be (3.96 ± 0.06), (4.00 ± 0.06) and (3.76 ± 0.06) eV, respectively. Combined with related thermochemical parameters, the standard enthalpies of formations of C8H8+, C8H7+, C8H6+ and C6H6+ are determined to be 964.2, 1346.3, 1350.2 and 1327.0 kJ/mol, respectively. Based on the theoretical study, the kinetic factors controlling the styrene dissociation reaction process are determined by using the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. This provides a reference for further research on the atmospheric photooxidation reaction mechanism of styrene in atmospheric and interstellar environments.

Biospecimens with nearly flat surfaces on a flat stage are typically required for laser-based mass spectrometry imaging (MSI) techniques. However, sampling stages are rarely perfectly level, and accounting for this and the need to accommodate non-flat samples requires a deeper understanding of the laser beam depth of focus. In ablation-based MSI methods, a laser is focused on top of the sample surface, ensuring that the sample is at the focal point or remains within depth of focus. In general, the depth of focus of a given laser is related to the beam quality (M2) and the wavelength (λ). However, because laser is applied on a biological sample, other variables can also impact the depth of focus, which could affect the robustness of the MSI techniques for diverse sample types. When the height of a sample ranges outside of the depth of focus, ablated area and the corresponding ion abundances may vary as well, increasing the variability of results. In this tutorial, we examine the parameters and equations that describe the depth of focus of a Gaussian laser beam. Additionally, we describe several approaches that account for surface roughness exceeding the depth of focus of the laser.

The thermal decomposition of the atmospheric constituent ethyl formate was studied by coupling flash pyrolysis with imaging photoelectron photoion coincidence (iPEPICO) spectroscopy using synchrotron vacuum ultraviolet (VUV) radiation at the Swiss Light Source (SLS). iPEPICO allows photoion mass-selected threshold photoelectron spectra (ms-TPES) to be obtained for pyrolysis products. By threshold photoionization and ion imaging, parent ions of neutral pyrolysis products and dissociative photoionization products could be distinguished, and multiple spectral carriers could be identified in several ms-TPES. The TPES and mass-selected TPES for ethyl formate are reported for the first time and appear to correspond to ionization of the lowest energy conformer having a cis (eclipsed) configuration of the O=C(H)–O–C(H2)–CH3 and trans (staggered) configuration of the O=C(H)–O–C(H2)–CH3 dihedral angles. We observed the following ethyl formate pyrolysis products: CH3CH2OH, CH3CHO, C2H6, C2H4, HC(O)OH, CH2O, CO2, and CO, with HC(O)OH and C2H4 pyrolyzing further, forming CO + H2O and C2H2 + H2. The reaction paths and energetics leading to these products, together with the products of two homolytic bond cleavage reactions, CH3CH2O + CHO and CH3CH2 + HC(O)O, were studied computationally at the M06-2X-GD3/aug-cc-pVTZ and SVECV-f12 levels of theory, complemented by further theoretical methods for comparison. The calculated reaction pathways were used to derive Arrhenius parameters for each reaction. The reaction rate constants and branching ratios are discussed in terms of the residence time and newly suggest carbon monoxide as a competitive primary fragmentation product at high temperatures.

Smoke dyes are complex molecular systems that have the potential to form many molecular derivatives and fragments when deployed. The chemical analysis of smoke samples is challenging due to the adiabatic temperature of the pyrotechnic combustion and the molecular complexity of the physically dispersed reaction products. Presented here is the characterization of the reaction byproducts of a simulant Mk124 smoke signal on a multigram scale, which contain the dye disperse red 9 (1-(methylamino)anthraquinone), by ambient ionization mass spectrometry. Our previous work has examined the thermal decomposition of a simplified smoke system consisting of disperse red 9, potassium chlorate, and sucrose by anaerobic pyrolysis gas chromatography mass spectrometry performed at the laboratory milligram scale. The results from the lab scale test were compared with a fully functioned Mk124 in the field. To achieve this, Mk124 smokes were functioned in the presence of sampling swabs that collected byproduct residues from the smoke plume in the ambient environment. These swabs were then analyzed using ambient ionization mass spectrometry to identify the expended pyrotechnic residues, with particular interest in halogenated species. Previous work determined the toxicity of unforeseen byproducts identified on the laboratory scale, which were also detected in the field demonstrating the correlation of the laboratory testing to the fielded systems. By understanding the chemical composition of smokes and their reaction products, potential toxicity effects can be easily assessed, leading to safer formulations with improved performance. These results can help assess how smoke byproducts may impact Warfighter performance, personnel health, and the environment.

The molecular composition of lubricating oils has a strong impact on how automotive engines function, but the techniques used to monitor the quality parameters of these oils only inspect their gross physical–chemical properties such as viscosity, color, and bulk spectroscopy profiles; hence, bad-quality, adulterated, or counterfeit oils are hard to detect. Herein, we investigated the ability of direct infusion electrospray ionization mass spectrometry (ESI-MS) to provide simple, rapid but characteristic fingerprint profiles for such oils of the mineral and synthetic types. After a simple aqueous extraction, ESI-MS analyses, particularly in the positive ion mode, did indeed show characteristic molecular markers with unique profiles, which were confirmed and more clearly visualized by partial least squares-discriminant analysis (PLS-DA). Nuclear magnetic resonance and Fourier transform infrared-attenuated total reflection spectroscopy were also tested for the bulk samples but showed nearly identical spectra, thus failing to reveal their distinct molecular composition and to differentiate the oil samples. To simulate adulteration, mixtures of mineral and synthetic oils were also analyzed by ESI(+)-MS, and additions as low as 1% of mineral oil to synthetic oil could be detected. The technique therefore offers a simple and fast but powerful tool to monitor the molecular composition of lubricant oils, particularly vias their more polar constituents.

Phlorizin (PRZ) is a natural product that belongs to a class of dihydrochalcones. The unique pharmacological property of PRZ is to block glucose absorption or reabsorption through specific and competitive inhibitors of the sodium/glucose cotransporters (SGLTs) in the intestine (SGLT1) and kidney (SGLT2). This results in glycosuria by inhibiting renal reabsorption of glucose and can be used as an adjuvant treatment for type 2 diabetes. The pharmacokinetic profile, metabolites of the PRZ, and efficacy of metabolites towards SGLTs are unknown. Therefore, the present study on the characterization of hitherto unknown in vivo metabolites of PRZ and pharmacokinetic profiling using liquid chromatography-electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) and accurate mass measurements is undertaken. Plasma, urine, and feces samples were collected after oral administration of PRZ to Sprague–Dawley rats to identify in vivo metabolites. Furthermore, in silico efficacy of the identified metabolites was evaluated by docking study. PRZ at an intraperitoneal dose of 400 mg/kg showed maximum concentration in the blood to 439.32 ± 8.84 ng/mL at 1 h, while phloretin showed 14.38 ± 0.33 ng/mL at 6 h. The pharmacokinetic profile of PRZ showed that the maximum concentration lies between 1 and 2 h after dosing. Decreased blood glucose levels and maximum excretion of glucose in the urine were observed when the PRZ and metabolites were observed in plasma. The identification and characterization of PRZ metabolites by LC/ESI/MS/MS further revealed that the phase I metabolites of PRZ are hydroxy (mono-, di-, and tri-) and reduction. Phase II metabolites are O-methylated, O-acetylated, O-sulfated, and glucuronide metabolites of PRZ. Further docking study revealed that the metabolites diglucuronide metabolite of mono-hydroxylated PRZ and mono-glucuronidation of PRZ could be considered novel inhibitors of SGLT1 and SGLT2, respectively, which show better binding affinities than their parent compound PRZ and the known inhibitors.

Psoraleae Fructus (PF) is one of the most frequently used traditional Chinese medicine, which has good efficacy in warming kidney to activate yang, promoting inspiration to relieve asthma and warming spleen to stop diarrhea. However, the chemical composition of PF is complex, which makes it difficult to determine its active and toxic components. In order to rapidly classify and identify the chemical components of the extracts from PF, this research was processed with CNKI, PubMed, and PubChem databases and data post-processing technique basing on ultrahigh performance liquid chromatography quadrupole orbitrap mass spectrometry (UPLC-Q-Orbitrap MS) technique. Finally, 73 chemical components were discriminated, including 44 flavonoids, 18 coumarins, and 11 terpenoids, with the cleavage rules of each chemical component summarized. This study established a UPLC-Q-Orbitrap MS method for the separation and discrimination of the chemical constituents of PF, which can lay a foundation for the further study of its medicinal substances and quality control.

Lanolin, also known as wool wax, is derived from sheep and has diverse applications in food, cosmetic, textile and lubricant industries. Owing to its direct contact with human, there is a need of studying pesticide residues as contaminants in lanolin. The present study describes a single novel hyphenated gas chromatography–tandem mass spectrometry (GC-MS/MS) technique for the quantification of 14 organophosphorus (OP) pesticides (tecnazene, propetamphos, diazinon, dichlofenthion, chlorpyrifos methyl, fenchlorphos, malathion, chlorpyrifos, pirimiphos ethyl, bromophos ethyl, tetrachlorvinphos, ethion, phosalone, and coumaphos) in lanolin using electrospray ionization (EI) with multiple reaction monitoring (MRM) acquisition mode. The method is simple in terms of sample preparation steps based on matrix solid-phase dispersion (MSPD). The method was found to be linear over the analytical range of 0.05–2.0 μg/g, with acceptable coefficient of determination (r2 ≥ 0.99) for all the 14 pesticides. The limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be less than 0.05 and 0.1 μg/g, respectively, for all the 14 OP pesticide residues. The precision and accuracy of the method were found to be within the acceptable limits, that is, recoveries in the range of 83.5%–104.1% with less than 12.5% of relative standard deviation for all the pesticides. The multiresidue method for estimating pesticide residues employing GC-MS/MS technique will be useful for OP pesticide levels in large number of lanolin samples.

Quantification of pharmaceutical compounds using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is an alternative to traditional liquid chromatography (LC)-MS techniques. Benefits of MALDI-based approaches include rapid analysis times for liquid samples and imaging mass spectrometry capabilities for tissue samples. As in most quantification experiments, the use of internal standards can compensate for spot-to-spot and shot-to-shot variability associated with MALDI sampling. However, the lack of chromatographic separation in traditional MALDI analyses results in diminished peak capacity due to the chemical noise background, which can be detrimental to the dynamic range and limit of detection of these approaches. These issues can be mitigated by using a hybrid mass spectrometer equipped with a quadrupole mass filter (QMF) that can be used to fractionate ions based on their mass-to-charge ratios. When the masses of the analytes and internal standards are sufficiently disparate in mass, it can be beneficial to effect multiple narrow mass isolation windows using the QMF, as opposed to a single wide mass isolation window, to minimize chemical noise while allowing for internal standard normalization. Herein, we demonstrate a MALDI MS quantification workflow incorporating multiple sequential mass isolation windows enabled on a QMF, which divides the total number of MALDI laser shots into multiple segments (i.e., one segment for each mass isolation window). This approach is illustrated through the quantitative analysis of the pharmaceutical compound enalapril in human plasma samples as well as the simultaneous quantification of three pharmaceutical compounds (enalapril, ramipril, and verapamil). Results show a decrease in the limit of detection, relative standard deviations below 10%, and accuracy above 85% for drug quantification using multiple mass isolation windows. This approach has also been applied to the quantification of enalapril in brain tissue from a rat dosed in vitro. The average concentration of enalapril determined by imaging mass spectrometry is in agreement with the concentration determined by LC–MS, giving an accuracy of 104%.

Sweet almond oil is a raw material with high-added value used in different products. Then, the aim of this study is to evaluate the quality and purity of 10 body oils based on sweet almond oils currently available in the Brazilian market. Fatty acid composition and triacylglycerol (TAG) profile were determined by gas chromatography with flame ionization detector (GC-FID) and atmospheric solids analysis probe mass spectrometry (ASAP-MS), respectively. The authenticity of samples was assessed using an analytical curve equation. Soybean oil was chosen as the adulterant because it is the cheapest vegetable oil commercialized in Brazil. Hierarchical clustering analysis (HCA) in conjunction with ASAP-MS classified product samples according to the type of vegetable oil (soybean and sweet almond oils). The addition of soybean oil (8.79% to 99.70%) was confirmed in samples. However, only two samples stated in their label the presence of soybean oil as an ingredient. These findings highlight the need for better oversight by regulatory bodies to ensure that consumers acquire high quality and authentic products based on equally high quality and purity of sweet almond oils.

Higher alcohols and esters are among the predominant classes of volatile organic compounds (VOCs) that influence the quality of beer. The concentrations of these compounds are determined through a specific yeast strain selection and fermentation conditions. The effect of yeast strains on the formation of higher alcohols and esters throughout fermentations (at 20°C) was investigated. Flavour-relevant esters (ethyl acetate, isoamyl acetate, ethyl hexanoate and ethyl octanoate) and higher alcohols (isoamyl alcohol, isobutyl alcohol and phenylethyl alcohol) were monitored throughout the fermentation using proton transfer reaction–time of flight–mass spectrometry (PTR-ToF-MS) coupled with an automated sampling system for continuous measurements. Compound identification was confirmed by analysis of samples using gas chromatography–mass spectrometry (GC–MS). Results demonstrated the specific time points where variation in higher alcohol and ester generation between yeast strains occurred. In particular, the concentrations of isoamyl acetate, ethyl octanoate and isoamyl alcohol between yeast strains were significantly different over the first 2 days of fermentation; whereas, after Day 3, no significant differences were observed. The two Saccharomyces pastorianus strains produced comparable concentrations of the key higher alcohols and esters. However, the key higher alcohol and ester concentrations varied greatly between the two S. cerevisiae strains. The use of PTR–ToF–MS to rapidly measure multiple yeast strains provides new insights on fermentation for brewers to modify the sensory profile and optimise quality.

Desalting oligonucleotides (ONs) for matrix assisted laser desorption ionization mass spectrometry (MALDI MS) analysis was achieved using a simple dissolve-spin approach. The ON is dissolved in an organic solvent. Insoluble salts are removed by centrifugation. ONs are highly polar molecules, and are generally believed insoluble in organic solvents with moderate polarity such as acetonitrile (ACN), 1,4-dioxane, ethyl acetate and THF. However, we found that in the presence of a suitable proton source such as pyridinium chloride, a quantity of ON that is sufficient for MALDI MS analysis could be dissolved. Because inorganic salts are insoluble in such relatively non-polar solvents, the finding can be utilized for desalting ONs for MALDI MS analysis. Comparisons of MS spectra of intentionally salted ONs that underwent the new desalting procedure with those that did not undergo the procedure provided unambiguous evidence that the desalting method is highly effective.

Gas chromatography–mass spectrometry (GC–MS) with Cold EI is based on interfacing GC and MS with supersonic molecular beams (SMBs) along with electron ionization of vibrationally cold sample compounds in SMB in a fly-through ion source (hence the name Cold EI). Cold EI improves all the central performance aspects of GC–MS, and in this paper, we focus on its improvement of signal-to-noise ratio (S/N) and limits of detection (LODs). We found that the harder the compound for analysis with standard EI, the greater the Cold EI gain in S/N and LOD. The lower LOD and higher S/N of Cold EI emerge from a few reasons: (a) similar ionization yield as standard EI, (b) enhanced abundance of molecular ions, (c) elimination of vacuum background noise, (d) elimination of ion source-related peak tailing and degradation, (e) ability to lower the elution temperatures via the use of high column flow rates, and (f) greater range of thermally labile and low-volatility compounds that can be analyzed. We demonstrate the superior S/N and lower LOD of Cold EI versus standard EI in a range of compounds, from the simple-to-analyze octafluoronaphthalene all the way to reserpine and an organo-metallic compound that cannot be analyzed by standard EI. These compounds include methyl stearate, cholesterol, n-C32H66, large polycyclic aromatic hydrocarbons, dioctyl phthalates, diundecyl phthalate, pentachlorophenol, benzidine, lambda-cyhalothrin, and methidathion. The significantly lower Cold EI LODs that can be over 1000 times better than in standard EI further result in far superior response linearity and greater measurement dynamic range.