Paper spray-atmospheric pressure photoionization-high resolution mass spectrometry for the direct analysis of neutral fluorinated compounds in waterproof impregnation sprays.

In this work, paper spray (PS) is combined with atmospheric pressure photoionization-mass spectrometry (PS-APPI-MS) for the determination of non-polar and low polar compounds, such as the neutral per- and polyfluorinated alkyl substances (PFAS). The proposed PS-APPI-MS method has been developed for the analysis of fluorotelomer alcohols (FTOHs), fluoroctanesulfonamides (FOSAs) and fluorooctane sulfonamido-ethanols (FOSEs), using both negative ion mode and high-resolution mass spectrometry (HRMS). The most critical working parameters (i.e., UV-krypton lamp position, sample drying time, spray dopant solvent and spray voltage) have been evaluated to study both the ionization behaviour and ionization efficiency. The best results were achieved using dopant-assisted PS-APPI-HRMS with toluene as dopant solvent. The most intense ions observed in the mass spectra, [M‒H]‒ for FOSAs and [M+O2]‒• for FTOHs and FOSEs, were selected and proposed for fast screening and quantitative analysis of target compounds in waterproof impregnation sprays samples using internal standard calibration method and being able to detect down to µg L-1 levels. The satisfactory values of the method quality parameters (detection capability, repeatability, trueness and linearity) demonstrated the good performance of the PS-APPI-HRMS method and allowed the identification and quantitation of some FTOHs (6:2 FTOH, 7-Me-6:2 FTOH, 8:2 FTOH, 10:2 FTOH) and N-MeFOSE at mg L-1 in some of the waterproof impregnation spray products analyzed. This low-cost PS-APPI-HRMS method allows a fast screening, with minimum sample preparation, of non-polar and low polar compounds simultaneously, which can significantly improve the throughput on routine laboratories.

Chloride-attachment atmospheric pressure photoionisation for the determination of short-chain chlorinated paraffins by gas chromatography-high-resolution mass spectrometry.

In this work, a new gas chromatography-high-resolution mass spectrometry (GC-HRMS) method based on atmospheric pressure photoionisation (APPI) has been developed for the accurate determination of short-chain chlorinated paraffins (SCCPs) as a reliable alternative to the established methods. To the best of our knowledge, this is the first time these compounds has been analysed by GC-MS using atmospheric pressure photoionisation (APPI). Efficient ionisation of SCCPs was achieved using the new GC-APPI source by the formation of [M+Cl]- adduct ions in negative ion mode using dopant-assisted APPI with a mixture of acetone/CCl4 (3:1, v/v). Operating at a resolution of 70,000 FWHM (full width at half maximum) and monitoring the [M+Cl]- adduct ions for each congener group, a selective determination of the SCCPs was achieved, avoiding isobaric interferences between homologue groups with different carbon chain length and chlorination degree. Moreover, the GC-APPI-HRMS response of each congener group was mainly influenced by its concentration and did not depend on the number of chlorine atoms in the molecule as occurs with the GC-MS methods based on the electron-capture negative ionisation (ECNI). Thus, the contribution of the different carbon and chlorine homologue groups in the SCCP mixtures was determined by the internal normalization method, and the quantification was performed independently of the chlorine content of the SCCP standard mixture employed. The developed GC-APPI-HRMS method offers some interesting advantages over the existing methods, particularly the possibility to quantify individual SCCP congener groups, the use of a simple calibration method for quantification, and an important time-saving in the data processing, especially over ECNI-based traditional methods. The GC-APPI-HRMS method allowed the determination of SCCPs at low concentration levels in fish samples with low method limits of detection (17-34 pg g-1 wet weight for total SCCPs), good precision (RSD < 7%) and trueness (relative error < 8%) and can be proposed as a reliable alternative of the established methods for the determination of these pollutants in environmental samples.

Determination of banned dyes in red spices by ultra-high-performance liquid chromatography-atmospheric pressure ionization-tandem mass spectrometry.

This paper reports the development of an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC‒MS/MS) method to determine eight banned dyes (Sudan I-IV, Sudan Orange, Sudan Red 7B, Para Red, Rhodamine B) in turmeric, curry, and chili products. For this purpose, the feasibility of electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) for the ionization of these compounds was evaluated. The tandem mass spectrometry (MS/MS) fragmentation of all targeted compounds was studied and both multistage mass spectrometry and high-resolution mass spectrometry were used to establish the fragmentation pathways and identify common fragmentation behaviors. Among the most significant ions, the most characteristic and abundant product ions observed on the triple quadrupole were selected to propose a selective and sensitive UHPLC‒MS/MS method (multiple reaction monitoring mode, MRM) of these target compounds in spices samples after a quick and easy extraction with acetonitrile. Matrix effect (ME) studies carried out in the three atmospheric pressure ionization sources have demonstrated that APCI showed the best performance with ME values ranging from 2 to 25%. Furthermore, the estimated quality parameters indicated the good performance of the proposed method, providing low method limits of detection (MLODs) (1-48 µg kg-1), good intra-day precision (RSD % < 15%), and accurate quantitation (relative error % < 15%). Finally, the applicability of the developed method was demonstrated by the analysis of turmeric, curry, and chili products. In total, 36 diverse samples coming from different countries were analyzed and although none of these compounds were detected above the MLODs, the analysis of spiked samples showed that the method was able to detect this family of compounds at low µg kg-1.

Papel de la cianocobalamina en el abordaje práctico de la eritrodermia paraneoplásica / Role of Cyanocobalamin Levels in Managing Paraneoplastic Erythroderma: A Practical Approach

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Correlation between dermoscopy and direct microscopy in Tineabarbae.

Tineabarbae is a rare form of dermatophytosis that affects hair follicles of the beard and moustache. Dermoscopy could prove useful to identify parasitism of hair of the beard, just as it has proven useful in the diagnosis of Tineacapitis. We present the first fully documented case series of T. barbae with clinical, dermoscopic and mycological features.

Atmospheric pressure ionization for gas chromatography-high resolution mass spectrometry determination of polychlorinated naphthalenes in marine sediments.

In this work, the performance of the atmospheric pressure chemical ionization (APCI) and photoionization (APPI) was assessed to develop a new selective and sensitive gas chromatography-high resolution mass spectrometry (GC-HRMS) method for the determination of polychlorinated naphthalenes (PCNs) in sediment samples. The capability of both APCI and APPI sources for the ionization of PCNs was investigated, showing the formation of the molecular ion and the [M‒Cl+O]‒ ion in positive and negative ion modes, respectively. Positive ion APCI provided high responses using high corona ion current, while the use of high vapour pressure dopant-solvents, such as toluene in positive mode and diethyl ether in the negative mode, was required to achieve high ionization efficiencies in APPI. The performance of the two API sources in the PCN determination by GC-HRMS were compared and the best results were achieved using the GC-APPI(+)-HRMS (Orbitrap) system. The GC-APPI(+)-HRMS (Orbitrap) method was applied to the characterization of Halowax mixtures and the analysis of marine sediments collected near to the coastal area of Barcelona (NE, Spain), demonstrating a great detection capability with low method limits of detection (0.2-1.6 pg g-1 dry weight), good precision (RSD <15%) and trueness (relative error <13%). Total PCN concentrations ranged from 0.35 to 5.0 ng g-1 dry weight and the presence of related compounds, such as polychlorinated biphenyls (PCBs), was also detected by combining positive and negative ion modes, providing complementary information to better monitor of all PCN congener groups. The results presented here show the feasibility of the GC-APPI-HRMS method for the suitable determination of PCNs.

Ionic Liquid Stationary Phase for Improving Comprehensive Two-dimensional Gas Chromatographic Separation of Polychlorinated Naphthalenes.

The performance of comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) using a column combination of a non-polar stationary phase (DB-5MS) and an ionic liquid stationary phase (SLB-IL60) in the first- and the second dimension has been evaluated for the suitable separation of polychlorinated naphthalenes (PCNs). The optimization of the GC×GC-MS method was carried out using different oven temperature programs and modulation conditions, achieving the best results using a ramp temperature rate of 0.75 °C min-1 and a modulation time of 12 s. Under these conditions, efficient separation of all PCN congeners present in Halowax formulations was achieved in 140 min, resolving some critical closed eluting isomers, such as CN-33/34/37, highly toxic CN-66/67 or CN-71/72 pairs, among others. These findings represent a significant improvement in the congener-specific separation of PCNs over the 1D-GC and GC×GC methodologies already published and the DB-5MS × SLB-IL60 column combination offered the orthogonality required for the congener-specific determination with a high peak capacity. The GC×GC-MS method was applied to the characterisation of Halowax formulations, obtaining similar compositional profiles than those previously reported.

Feasibility of gas chromatography-atmospheric pressure photoionization-high-resolution mass spectrometry for the analysis of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in environmental and feed samples.

In this work, the suitability of atmospheric pressure photoionization (APPI) has been assessed for the determination of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) by gas chromatography-high-resolution mass spectrometry (GC-HRMS). The APPI of target compounds has been tested in both positive and negative ion modes. Under positive ion mode, the analytes generated the molecular ion, which was favoured using dopants that promote charge exchange gas-phase reactions (i.e., benzene), while in negative ion mode, the ion [M-Cl+O]- for PCDFs and dl-PCBs were mainly formed, providing the best results using benzene and diethyl ether as dopants, respectively. Concerning PCDDs, highly chlorinated congeners were mainly ionized by means of the [M-Cl]- ion, whereas [M-Cl+O2]- was the base peak for tetraCDD and [M-Cl+O]- for penta- and hexaCDDs. Method quality parameters, in accordance with the current EU Regulation guidelines for food and feed analysis, showed the good performance of the two GC-APPI-HRMS (Orbitrap) methods since they provided high detection capability (low fg levels), good linearity, and satisfactory precision (RSD% < 9%). In addition, the GC-APPI-HRMS (Orbitrap) methods were validated by analysing selected environmental and feed samples and the results were compared to those obtained using conventional GC-EI-HRMS, demonstrating the good performance in the analysis of the target compounds. Hence, the GC-APPI-HRMS technique can be proposed as alternative to the conventional methods for the determination of PCDD/Fs and dl-PCBs in environmental and feed matrices.

A novel methodology for the determination of neutral perfluoroalkyl and polyfluoroalkyl substances in water by gas chromatography-atmospheric pressure photoionisation-high resolution mass spectrometry.

Here, we developed and validated a new gas chromatography-atmospheric pressure photoionisation-high-resolution mass spectrometry (GC-APPI-HRMS) method combined with headspace solid-phase microextraction (HS-SPME) for the determination of neutral perfluoroalkyl and polyfluoroalkyl substances (PFASs) in water samples. The method includes fluorotelomer olefins (FTOs), fluorotelomer alcohols (FTOHs), fluoroctanesulfonamides (FOSAs) and sulfonamido-ethanols (FOSEs). The feasibility of the GC-APPI interface for the ionisation of the target compounds was evaluated, achieving the best results using negative-ion dopant-assisted ionisation with acetone and a source and capillary temperatures of 225 °C and 175 °C, respectively. Under optimal conditions, FTOs and FTOHs mass spectra showed intense in-source CID fragment ions from the fluoroalkyl chain but also the superoxide [M+O2]-• adduct ion. For FOSAs, [M-H]- was the main ion generated, while FOSEs mass spectra showed fragment ions corresponding to the different cleavages of the functional group. The high ionisation efficiency achieved with the GC-APPI interface provided limits of the detection lower than those obtained using traditional GC-MS ionisation techniques, with a high sensitivity, selectivity and precision. For water analysis, a fast and simple HS-SPME procedure was developed, avoiding evaporation steps, which could lead to the loss of the most volatile compounds. The developed HS-SPME GC-APPI-HRMS method showed a good analytical performance for the analysis of river water samples, providing very low limits of detection (0.02-15 ng L-1), good repeatability (RSD < 11%) and trueness (relative error < 12%).

Gas chromatography and liquid chromatography coupled to mass spectrometry for the determination of fluorotelomer olefins, fluorotelomer alcohols, perfluoroalkyl sulfonamides and sulfonamido-ethanols in water.

In this work, the suitability of gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the multi-class determination of different families of neutral per- and polyfluoroalkyl substances (PFASs), such as fluorotelomer olefins (FTOs), alcohols (FTOHs) and fluorooctanesulfonamides (FOSAs) and sulfonamido-ethanols (FOSEs), was investigated and compared. Regarding GC-MS, the use of a semi-polar GC column (DB-624, 6%-cyanopropilphenyl 94%-dimethyl polysiloxane) allowed the adequate separation of all the compounds while chemical ionisation (CI) of positive ions as ionisation technique provided the best responses. Concerning UHPLC-MS/MS, atmospheric pressure chemical ionisation (APCI) and photoionisation (APPI) sources allowed the ionisation of all studied neutral PFASs, including FTOs for the first time. High vaporizer temperatures (450 °C) and acetonitrile/water mobile phase mixtures were required to favour the ionisation of FTOs, with adequate ionisation for FTOHs, FOSAs and FOSEs. The chromatographic separation, performed on a totally porous column (Luna C18), allowed the successful separation of the four families of neutral PFASs. After comparing the performance of the studied methods, the highest detectability was achieved using UHPLC-APCI-MS/MS and it was chosen in combination with a solid-phase extraction (SPE) procedure for the analysis of neutral PFASs in water samples. The whole method provided low limits of detection (0.003-6 µg L-1), good precision (RSD < 9%) and trueness (relative error < 10%). The methodology was applied to the analysis of river water samples and the presence of some neutral PFASs were detected (8:2 FTO) and quantified (4:2 FTOH and N-EtFOSA) at low concentration levels (ng L-1).

Synthesis of new cyano-substituted analogues of Tröger's bases from bromo-derivatives. A stereochemical dependence of long-range (n JHH , n = 4, 5, and 6) proton-proton and proton-carbon (n JCH , n = 1, 2, 3, 4, and 5) coupling constants of these compounds.

A free-catalyst microwave-assisted cyanation of brominated Tröger's base derivatives (2a-f) is reported. The procedure is simple, efficient, and clean affording the nitrile compounds (3a-e, I) in very good yields. Complete assignment of 1 H and 13 C chemical shifts of 2a-f, I and 3a-d, I was achieved using gradient selected 1D nuclear magnetic resonance (NMR) techniques (1D zTOCSY, PSYCHE, DPFGSE NOE, and DEPT), homonuclear 2D NMR techniques (gCOSY and zTOCSY), and heteronuclear 2D NMR techniques (gHSQCAD/or pure-shift gHSQCAD, gHMBCAD, bsHSQCNOESY, and gHSQCAD-TOCSY) with adiabatic pulses. Determination of the long-range proton-proton coupling constants n JHH (n = 4, 5, 6) was accomplished by simultaneous irradiation of two protons at appropriate power levels. In turn, determined coupling constants were tested by an iterative simulation program by calculating the 1 H NMR spectrum and comparing it to the experimental spectrum. The excitation-sculptured indirect-detection experiment (EXSIDE) and 1 H-15 N CIGARAD-HMBC (constant time inverse-detection gradient accordion rescaled heteronuclear multiple bond correlation) were applied for determination of long-range carbon-proton coupling constants n JCH (n = 2, 3, and 4) and for assignment of 15 N chemical shift at natural abundance, respectively. DFT/B3LYP optimization studies were performed in order to determine the geometry of 2c using 6-31G(d,p), 6-311G(d,p), and 6-311 + G(d,p) basis sets. For calculation of 1 H and 13 C chemical shifts, n JHH (n = 2, 3, 4, 5, and 6), and n JCH (n = 1, 2, 3, and 4) coupling constants, the GIAO method was employed at the B3LYP/6-31G(d,p), B3LYP/6-31+G(d,p), B3LYP/6-311+G(d,p), B3LYP/6-311++G(2d,2p), B3LYP/cc-pVTZ), and B3LYP/aug-cc-pVTZ) levels of theory. For the first time, a stereochemical dependence magnitude of the long-range n JHH (n = 4, 5, and 6) and n JCH (n = 1, 2, 3, 4, and 5) have been found in bromo-substituted analogues of Tröger's bases.

Desorption electrospray ionization-high resolution mass spectrometry for the analysis of unknown materials: The phytosanitary product case.

In this work, we tested the potential of desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) for the analysis of unknown materials. To this end, our study focused on analyzing an unknown complex sample suspected of being an adulterated phytosanitary product or a fraud. A simple and fast sample manipulation procedure (filter paper impregnated with the sample) was used for the chemical characterization of the phytosanitary product by DESI-HRMS(/MS). Kendrick Mass Defect (KMD) analysis was used to process the DESI high-resolution mass spectral data, allowing the identification of a low molecular weight polymer (polyethylene glycol) and the detection of other ions, which did not follow polymer distributions. The characteristic isotope patterns of these ions suggested the presence of organometallic compounds. Accurate mass measurements, isotope pattern fits and the structural information obtained by DESI-MS/HRMS (wide isolation window) allowed identifying the presence of triphenyltin, a biocide extensively used for agricultural purposes and restricted by the European Commission, in the phytosanitary product. The concentration of triphenyltin in the sample was 35%, which corresponds to ∼12% expressed as weight of tin, 120 times higher than the maximum legislated level.

Computer-aided molecular design of pyrazolotriazines targeting glycogen synthase kinase 3.

Numerous studies have highlighted the implications of the glycogen synthase kinase 3 (GSK-3) in several processes associated with Alzheimer's disease (AD). Therefore, GSK-3 has become a crucial therapeutic target for the treatment of this neurodegenerative disorder. Hereby, we report the design and multistep synthesis of ethyl 4-oxo-pyrazolo[4,3-d][1-3]triazine-7-carboxylates and their biological evaluation as GSK-3 inhibitors. Molecular modelling studies allow us to develop this new scaffold optimising the chemical structure. Potential binding mode determination in the enzyme and the analysis of the key features in the catalytic site are also described. Furthermore, the ability of pyrazolotriazinones to cross the blood-brain barrier (BBB) was evaluated by passive diffusion and those who showed great GSK-3 inhibition and permeation to the central nervous system (CNS) showed neuroprotective properties against tau hyperphosphorylation in a cell-based model. These new brain permeable pyrazolotriazinones may be used for key in vivo studies and may be considered as new leads for further optimisation for the treatment of AD.

Synthesis and preliminary structure-activity relationship study of 2-aryl-2H-pyrazolo[4,3-c]quinolin-3-ones as potential checkpoint kinase 1 (Chk1) inhibitors.

The serine-threonine checkpoint kinase 1 (Chk1) plays a critical role in the cell cycle arrest in response to DNA damage. In the last decade, Chk1 inhibitors have emerged as a novel therapeutic strategy to potentiate the anti-tumour efficacy of cytotoxic chemotherapeutic agents. In the search for new Chk1 inhibitors, a congeneric series of 2-aryl-2 H-pyrazolo[4,3-c]quinolin-3-one (PQ) was evaluated by in-vitro and in-silico approaches for the first time. A total of 30 PQ structures were synthesised in good to excellent yields using conventional or microwave heating, highlighting that 14 of them are new chemical entities. Noteworthy, in this preliminary study two compounds 4e2 and 4h2 have shown a modest but significant reduction in the basal activity of the Chk1 kinase. Starting from these preliminary results, we have designed the second generation of analogous in this class and further studies are in progress in our laboratories.