Negative Ion Research Articles

Effects of negative hydroxyl ions at the SnO2/perovskite layer interface on the performance of perovskite solar cells

Effects of negative hydroxyl ions at the SnO2/perovskite layer interface on the performance of perovskite solar cells

Evaluating a novel method for vitamin A analysis in an observational study of the UAE's obese population

Vitamin A plays a critical role in various biological functions, including vision, cellular differentiation, and immune regulation. However, accurately assessing its status, particularly in obese individuals, presents challenges due to potential alterations in metabolism and distribution. This study utilized Liquid Chromatography–Tandem Mass Spectrometry (LC–MS/MS) methodology to precisely measure serum vitamin A concentrations in population of UAE. The methodology's reliability and precision, as demonstrated through validation procedures, underscore its potential utility in clinical settings. Employing the Multiple Reaction Monitoring mode of positive ion electrospray ionization, the LC–MS/MS system achieves a limit of detection (LOD) of 0.48 ng/mL in serum, while adhering to FDA-US regulations for accuracy and compliance. A key aspect of this study was the application of LC–MS/MS to assess vitamin A status in an obese population within UAE. By employing a diverse cohort of 452 Emirati participants, including 277 individuals from a randomized controlled trial who were assessed at baseline and at 6th month, and 175 healthy individuals aged 18–82 assessed at baseline, this study explores the relationship between obesity and vitamin A levels, shedding light on potential implications for health and well-being. It was an observational study based on a new vitamin A method and participants were asked to eat vitamin A rich foods. The robust performance of the LC–MS/MS methodology positions it as a valuable tool for clinical research. By accurately quantifying vitamin A levels in human serum, this methodology opens avenues for advancing our understanding of vitamin A physiology and its implications for health, particularly in obese populations. In summary, this LC–MS/MS methodology presents a potent tool for clinical studies, providing reliable, specific, and robust detection of vitamin A in human serum, thus, opening a new frontier for advancing our understanding of vitamin A related physiology and health in the obese population.

Determination of monocrotaline and usaramine in rat plasma by UPLC-MS/MS and their pharmacokinetics

AbstractAn ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of monocrotaline and usaramine in rat plasma, to study the plasma drug concentration and pharmacokinetics, and to calculate the absolute bioavailability. The plasma was treated with acetonitrile and methanol (9:1, v/v) protein precipitation method. The chromatographic column was UPLC HSS T3 (50 mm × 2.1 mm, 1.7 μm), the mobile phase was methanol-water (containing 0.1% formic acid with 10 mM ammonium acetate in water), and the elution time was 4 min at a flow rate of 0.4 mL min−1. Electrospray ionization (ESI) positive ion mode was used for detection and multiple reaction monitoring (MRM) mode was used for quantitative analysis. Monocrotaline and usaramine were administered sublingual intravenously (iv) 1 mg kg−1 and orally (po) 5 mg kg−1, respectively, with 6 rats in each group, for a total of 24 rats. Then the pharmacokinetic differences in rats were evaluated. For the UPLC-MS/MS method, the calibration curve showed good linearity in the range of 2–2,000 ng mL−1, where r was greater than 0.99. The precision, accuracy, recovery, matrix effect and stability results were all consistent with the requirements of biological sample detection methods. to provide scientific experimental basis for the basic research The bioavailability of monocrotaline and usaramine in rat plasma was calculated, which was 43.5 and 19.5%, respectively.

Generation of seed electrons in guided ionization waves in He–O2 mixtures: The effect of negative ion cluster formation

The kinetics of electrons and negative ions was numerically studied under the conditions, which are typical for multi-pulsed guided ionization waves in He flows ejected into ambient air. It was shown that, in He with a small admixture of O2 or air, O2− ions formed due to three-body electron attachment in the discharge afterglow are rapidly converted to O4− cluster ions in pulse off time. We suggested that seed electrons are generated at the leading edge of a pulse in two steps, and these steps are dissociation of O4− ions to form O2− ions followed by electron detachment from the O2− ions. The rate of O4− dissociation was calculated in He–O2 mixtures for various reduced electric fields on the basis of a Monte Carlo simulation. This rate, as well as the rate of electron detachment from O2− ions calculated previously, was used to simulate seed electron generation in a high-voltage nanosecond pulse in He–O2 mixtures for different gas pressures. It was shown that the formation of O4− ions drastically hinders the generation of seed electrons in multi-pulsed guided ionization waves in He–O2 and He–air mixtures.

Numerical simulation of dynamics behavior of pre-ionized pulsed-DC helium plasma jets at atmospheric pressure

A two-dimensional axisymmetric fluid model was established to investigate the dynamic behavior of pre-ionized pulsed-direct-current helium plasma jets at atmospheric pressure. Our simulation results show that, at a relatively low pre-ionization level, the electron number density is reduced and the streamer propagation is decelerated before the plasma jet is ejected from the tube, which is attributed to the inhibitory effect of a recombination process between the positive ions in the streamer and the seed electrons near the anode. As the pre-ionization reaches a relatively high level, the electron number density is larger than that without pre-ionization before the plasma jet is ejected from the tube, which originates from the promotion effect of decreased breakdown voltage. These two competing mechanisms jointly dominate the dynamic behavior of gas discharge in the presence of pre-ionization. After the plasma jet is ejected from the tube, the enhanced discharge power is responsible for the strengthened electric field in the streamer head, augmented total ionization rate, accelerated streamer propagation, and increased number density of electrons and active species, whatever the pre-ionization density is. With the increase in pre-ionization density, the plasma jet length, streamer propagation speed, discharge power, and discharge energy exhibit the initial increase and subsequent decrease variation trend. The optimal enhancement effect is obtained at the pre-ionization density of 6 × 1012 m−3, with the plasma jet lengthened by 28.4% and the energy deposition efficiency enhanced by 28.1%.

Identification of chemical components of large-leaf yellow tea by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Large-leaf yellow tea, a slightly fermented yellow tea that is unique to China, has a stronger hypoglycemic effect than other tea varieties, such as green and black tea. Research on large-leaf yellow tea has focused on its hypoglycemic effect owing to the lack of comprehensive techniques to characterize its chemical components; thus, its development and further promotion are limited. Therefore, the development of a reliable analytical method to fully characterize the chemical components of large-leaf yellow tea is urgently required. In this study, a reliable strategy based on the data-acquisition technology of ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q TOF/MS) was established to rapidly screen and analyze the main chemical components of large-leaf yellow tea by combining the information of neutral loss groups and characteristic fragment ions. The chromatographic separation experiments were performed on a Waters ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution using 0.1% formic acid aqueous solution and acetonitrile as the mobile phases. The flow rate was 0.2 mL/min, the sample volume was 2 μL, and the column temperature was 35 ℃. The mass spectral information of the components in a large-leaf yellow tea solution was collected using the full-information tandem MS (MSE) technique in positive and negative ion modes. The specific chemical components of large-leaf yellow tea was identified as follows. First, a self-established database of tea chemical components was constructed based on the literature. The mass spectral cleavage pathways of different types of compounds in large-leaf yellow tea were then sorted using reference substances, and the characteristics of the fragment ions and neutral loss groups were summarized. The precise mass-to-charge ratio of the target chemical components were then obtained based on the mass spectral information. Finally, the structures of the compounds in large-leaf yellow tea were confirmed based on their chromatographic retention times, mass spectral cleavage pathways, characteristic fragment ions, and neutral loss groups. A total of 87 chemical components, including 10 catechins, 32 flavonoids, 16 phenolic acids, 12 tannins, 6 theaflavins, and 11 compounds in other classes, were identified in large-leaf yellow tea. Representative compounds of various classes, including gallocatechin gallate, quercetin, vitexin, gallic acid, chlorogenic acid, 1,3,6-tri-O-galloyl-β-D-glucose, and theaflavin, were selected, and their characteristic fragment ions and neutral loss groups were investigated in detail to reveal the cleavage pathways of different types of compounds in large-leaf yellow tea. The UPLC-Q TOF/MS method established in this study can comprehensively identify the main chemical components of large-leaf yellow tea in a simple, highly sensitive, stable, and reliable manner. This study provides a scientific basis and data support for the discovery of functional ingredients and quality evaluation of large-leaf yellow tea.

Rapid determination of chlorate and perchlorate in tea by ion exchange chromatography-tandem mass spectrometry

Ion exchange chromatography-tandem mass spectrometry (IEC-MS/MS) has recently become the preferred method for detecting ionic substances in tea. In this study, an IEC-MS/MS method was developed for the rapid determination of chlorate and perchlorate residues in tea samples. The optimal sample extraction process, pretreatment column, and chromatographic and mass spectrometric conditions were systematically investigated. In the optimal process, the tea samples were ultrasonically extracted with methanol-water (13∶7, v/v), and a PRiME HLB SPE column was used to purify the sample extract. An AceChrom Hybri-A IEC column (150 mm×2.1 mm, 5.0 μm) was used for separation, and 100 mmol/L ammonium acetate-acetonitrile (40∶60, v/v) was used as the mobile phase for isocratic elution. The flow rate was 0.3 mL/min, the column temperature was 40 ℃, and the injection volume was 5.0 μL. The mass spectrometric data were collected in negative electrospray ionization mode combined with multiple reaction monitoring (MRM) mode to achieve the rapid and accurate separation and qualitative analysis of the desired chemical components. Quantification was performed using the internal standard (IS) method. The measurement results showed a good linear relationship when the mass concentrations of chlorate and perchlorate were between 2.00-200 and 1.00-100 μg/L, respectively, with correlation coefficients (r2) greater than 0.9990. The average recoveries of chlorate and perchlorate at three spiked levels of low, medium, and high ranged from 88.54% to 97.25% with relative standard deviations (RSDs, n=7) of 3.2%-5.2%. The limits of detection for chlorate and perchlorate were 12.0 and 8.0 μg/kg, respectively, while the limits of quantification were 40.0 and 26.6 μg/kg, respectively. The results of tests conducted to assess the linearity, specificity, accuracy, precision, and applicability of the method to the analysis of chlorate and perchlorate in 15 tea samples collected from a local market demonstrated its validity for the routine analysis of tea samples. The proposed method is simple, rapid, sensitive, and accurate, and can meet requirements for the rapid screening and quantitative analysis of residual trace chlorate and perchlorate in large quantities of tea samples.

Numerical investigation of vacuum ultra-violet emission in Ar/O2 inductively coupled plasmas

Abstract Controlling fluxes of vacuum ultraviolet (VUV) radiation is important in a number of industrial and biomedical applications of low pressure plasma sources because, depending on the process, VUV radiation may be desired, required to a certain degree, or unwanted. In this work, the emission of VUV radiation from O atoms is investigated in low-pressure Ar/O2 inductively coupled plasmas via numerical simulations. For this purpose, a self-consistent Ar/O2 plasma-chemical reaction scheme has been implemented in a zero dimensional plasma chemical kinetics model and is used to investigate VUV emission from excited O atoms (3s 5S 2 0 and 3s 3S 1 0 ) at 130 and 135 nm. The model is extensively compared with experimental measurements of absolute VUV emission intensities, electron densities and Ar excited state densities. In addition, oxygen VUV emission intensities are investigated as a function of pressure, Ar/O2 mixture, and power deposition and the dominant reaction pathways leading to oxygen VUV emission are identified and described. In general terms, absolute oxygen VUV emission intensities increase with power and oxygen fraction over the ranges investigated and peak emission intensities are found for pressures between 5–50 Pa. The emission is dominated by the 130 nm resonance line from the decay of the O(3s 3S 1 0 ) state to the ground state. Besides, at low pressure (0.3–1 Pa), the flux of oxygen VUV photons to surfaces is much lower than that of positive ions, whereas oxygen VUV fluxes dominate at higher pressure, ≳ 5–50 Pa depending on O2 fraction. Finally, oxygen atom fluxes to surfaces are, in general, larger than those of VUV photons for the parameter space investigated.

Shear-flow driven ion-acoustic instability in a non-thermal magnetoplasma

Relying on the kinetic model, we study linear properties of ion-acoustic waves in a non-thermal magnetoplasma, whose constituents are the electrons and singly charged positive ions. For this purpose, we solve a set of coupled Vlasov–Poisson equations within the framework of an unperturbed orbit theory and Fourier transformations. A generalized dielectric function is derived in a Cairns distributed plasma to investigate the electrostatic ion-acoustic waves with weak ion shear flows and ion streaming effects. It is found that the magnitude of the growth rate of the wave increases by varying the non-thermality and ion shear flow parameters. Furthermore, the wave spectrum and instability involving the ion-acoustic waves are analyzed with different plasma parameters in a non-thermal plasma. The present findings also reveal both analytical and numerical analyses of the electrostatic waves in the upper ionosphere, where non-thermal plasma particles are common.

Dust–ion–acoustic damped solitary waves and shocks in laboratory and Saturn's E-ring magnetized nonthermal dusty plasmas with anisotropic ion pressure and dust-charge fluctuation

We study the oblique propagation of weakly nonlinear dust–ion–acoustic (DIA) solitary waves (SWs) and shocks in collisional magnetized nonthermal dusty plasmas that are relevant in laboratory and space (Saturn's E-ring) environments. We consider plasmas to be composed of q-nonextensive hot electrons, thermal positive ions, and immobile negatively charged dust grains immersed in a static magnetic field and take into account the effects of ion creation (source), ion loss (sink), ion–neutral and ion–dust collisions, anisotropic ion pressure, and dust-charge fluctuations on the evolution of small-amplitude SWs and shocks. The ion–neutral collision enhancement equilibrium dust-charge number is self-consistently determined using Newton–Raphson method. We found that in laboratory dusty plasmas with adiabatic dust-charge variation [i.e., when the dust charging frequency (νch) is much higher than the dust–plasma oscillation frequency (ωpd)], the DIA solitary waves (DIASWs) get damped by the effects of the ion–dust and ion–neutral collisions, whereas the ion creation and ion loss lead to the amplification of solitary waves, and they appear as only compressive types with positive potential. On the other hand, in Saturn's E-ring plasmas, where the collisional and ion creation or ion loss effects are insignificant, the non-adiabaticity of dust-charge variation can give rise to the evolution of either damped DIASWs or DIA shocks, depending on the smallness of the ratios νch/ωpd or ωpd/νch, respectively. Furthermore, two critical values of the nonextensive parameter q exist, below (or above) which, the DIASWs and shocks can appear as rarefactive (or compressive) types. The characteristics of DIASWs and shocks are also analyzed numerically for parameters relevant to the laboratory and Saturn's E-ring plasmas.

Reassuring Quantitative Analysis of Glyphosate and Aminomethylphosphonic Acid Levels in Breast Milk Using Liquid Chromatography Mass Spectrometry.

Purpose: The World Health Organization's International Agency on Research for Cancer has determined that glyphosate is "probably carcinogenic to humans." There is a great public interest to investigate whether glyphosate are detected in breast milk. Thus, the goal of this study was to assess the concentration of glyphosate and its main metabolite in breast milk. Materials and Methods: Liquid chromatography was performed at 25°C using a Luna NH2, 50 × 2 mm, 3⎛ m (Phenomenex) analytical column. Electrospray ionization mass spectrometry was collected using negative ionization mode. The calibration curve for glyphosate ranged from 10 to 250 ng/mL. The detection limit was 1 ng/mL. Results: Breast milk samples were collected from 74 women, which included vegans (n = 26), vegetarians (n = 22), and nonvegetarians (n = 26). One of the 74 milk samples contained a detectable concentration of glyphosate and an additional 7 were found to contain aminomethylphosphonic acid. Conclusions: In breast milk samples collected mainly from women residing in urban regions of the United States, glyphosate detection was rare. Consistently, breastfed infants have a low or minimal risk of being exposed to glyphosate through ingestion of mother's milk. It is possible that the presence/absence and/or level of concentration of milk glyphosate depend on a place of residency and time of breastfeeding vis-à-vis time of its agricultural application.

Annealing effects on 100 keV silicon negative ions implanted SiO2 thin films

SiO2 thin film of thickness 300 nm grown on p-type silicon substrate was implanted with 100 keV silicon negative ions for the fluences of 1 × 1016, 5 × 1016, and 1 × 1017 ions cm−2. The implanted samples were investigated using an energy-dispersive X-ray (EDX) spectroscopic technique, and the samples were annealed at a temperature of 900 oC under N2 ambient. Ultraviolet–visible near infrared (UV-Vis-NIR) spectroscopy has been used to investigate the implanted SiO2 thin film samples before and after thermal annealing. EDX results revealed an increase in the atomic percentage and weight percentage of silicon ions as compared to oxygen ions in SiO2 thin film. This may be due to the increase in the concentration of silicon ions with the increase of implanted ion fluences within the SiO2 thin film. UV-Vis-NIR studies showed higher transmittance for thermally annealed samples as compared to non-annealed samples. This may be attributed to the creation of a new SiOx phase in the SiO2 matrix at higher temperatures. UV-Vis-NIR studies also exhibited an increase in the energy band gap value after thermal annealing. This effect may be related to the formation of silicon nanoclusters in SiO2 thin film.

Pharmacokinetics of Oleandrin Following Administration of a Nerium oleander Extract in Mice

Background. Nerium oleander Linn is native of Mediterranean regions of Africa and Europe, where it is used in folk medical practices. The whole plant is known to be toxic. Various studies have shown its antimicrobial and anticancer properties. Oleandrin, the main toxic component in Nerium oleander is an inhibitor of P-glycoprotein. Cardiac glycosides, including oleandrin, are substrates of P-glycoprotein. The presence of other inhibitors in the alcoholic extract may potentially modify the pharmacokinetics of oleandrin. Given the therapeutic potential and the associated toxicity of the alcoholic extract, it is important to investigate the kinetics of oleandrin within this extract. Purpose. The objective of this study was to determine the pharmacokinetic parameters in mice following oral and I.V. administrations of a hydroalcoholic extract of Nerium oleander. Methods. Pharmacokinetic investigations of oleandrin, a cardiotonic glycoside and main active compound in Nerium oleander, were conducted in mice following intravenous administration (30 mg/kg) and oral administration (150 mg/kg) of the hydrolcoholic extract of Nerium oleander. For the oral route, seven times were chosen for the mice sampling. Four times were chosen for the intravenous route. Three mice per group were used at each time point. In the excretion study, seven mice were housed in a mouse urine collection device and a dose of 150 mg/g was administered. A urine sample was collected after 48 hours. Oleandrin was measured by LC-MS/MS validated method. MS data were acquired in the positive ion electrospray ionization (ESI) mode. Two deuterated internal standards, cocaine-d3 and digoxin-d3, were used. The retention times were 8.47 min for oleandrin, 4.78 min for deuterated internal standard cocaine d3 and 5,37 min for deuterated internal standard digoxin d3. Results. The equivalent doses of oleandrin administred to mice were 1710 ug/kg for the oral route and 342 ug/kg for the intravenous route. Oleandrin was rapidly absorbed after oral administration (Cmax at 10 min). The AUC0-inf (ug/L*min) values obtained after intravenous and oral dosing were 34797.7 and 107222 respectively, resulting in an oral bioavailability of 61.6 %. The apparent volume of distribution (Vss) was 0.55 L/kg and Clearance ClT was 0.01 kg* L/min.

Application of a Novel UPLC-MS/MS Method for Analysis of Rivaroxaban Concentrations in Dried Blood Spot and Plasma Samples Collected from Patients with Venous Thrombosis.

Despite a higher safety profile compared to vitamin K antagonists, rivaroxaban therapy is still connected with multiple adverse effects, such as a high risk of bleeding. Thus, therapeutic drug monitoring (TDM) of rivaroxaban concentrations is suggested. An alternative to plasma samples can be dried blood spots (DBS), which minimize the cost of sample storage and transport. In this study, we developed a UPLC-MS/MS method for the analysis of rivaroxaban in DBS and plasma samples. Chromatographic separation was achieved on a Zorbax Eclipse Plus C18 column (2.1 × 100 mm; 3.5 µm, Agilent Technologies Inc., Santa Clara, CA, USA) with a mobile phase consisting of water and acetonitrile, both containing 0.1% formic acid. The analytes were detected using a positive ionization mode by multiple reaction monitoring. We validated the method according to ICH guidelines. The precision and accuracy were satisfactory. Extraction recovery was approximately 57% and 66% for DBS and plasma samples, respectively. A high correlation between rivaroxaban concentrations in plasma and DBS samples collected from patients was confirmed with Deming regression. The suitability of both sampling techniques for the rivaroxaban TDM was also verified by Bland-Altman plots based on DBS-predicted and observed plasma concentrations. In addition, we found a significant relationship between rivaroxaban concentrations and coagulation parameters, including prothrombin time (PT) and international normalized ratio (INR).

SF6 Negative Ion Formation in Charge Transfer Experiments.

In the present work, we report an update and extension of the previous ion-pair formation study of Hubers, M.M.; Los, J. Chem. Phys.1975, 10, 235-259, noting new fragment anions from time-of-flight mass spectrometry. The branching ratios obtained from the negative ions formed in K + SF6 collisions, in a wide energy range from 10.7 up to 213.1 eV in the centre-of-mass frame, show that the main anion is assigned to SF5- and contributing to more than 70% of the total ion yield, followed by the non-dissociated parent anion SF6- and F-. Other less intense anions amounting to <20% are assigned to SF3- and F2-, while a trace contribution at 32u is tentatively assigned to S- formation, although the rather complex intramolecular energy redistribution within the temporary negative ion is formed during the collision. An energy loss spectrum of potassium cation post-collision is recorded showing features that have been assigned with the help of theoretical calculations. Quantum chemical calculations for the lowest-lying unoccupied molecular orbitals in the presence of a potassium atom are performed to support the experimental findings. Apart from the role of the different resonances participating in the formation of different anions, the role of higher-lying electronic-excited states of Rydberg character are noted.

Sequencing of Phosphorodiamidate Morpholino Oligomers by Hydrophilic Interaction Chromatography Coupled to Tandem Mass Spectrometry.

Sequencing of phosphorodiamidate morpholino oligomers (PMOs) by hydrophilic interaction chromatography (HILIC) coupled to tandem mass spectrometry (MS/MS) is reported. The MS/MS analysis was performed using a quadrupole/time-of-flight (Q-ToF) mass analyzer and collision induced dissociation (CID) in negative ion mode. To improve MS sensitivity in negative ion mode, HILIC conditions, including the separation column, mobile phases, and MS parameters, were optimized. Using the developed HILIC-CID-MS/MS method, 100% sequence coverage was achieved for PMOs ranging from 18-mer to 25-mer. Additionally, the method was successfully applied to identifying positional isomers of n - 1 deletion impurities present in PMO drug substances.

Untargeted metabolic analysis of Epaltes mexicana by LC-QTOF-MS: Terpenes with activity against human cancer cell lines

Epaltes mexicana is a plant widely used in traditional medicine and as a food in Mexico; however, its phytochemical and pharmacological studies are limited. This study aimed to identify the active secondary metabolites of Epaltes mexicana and determine its cytotoxic activity on cancer cell lines. Three organic extracts were obtained by maceration using n-hexane, dichloromethane, and methanol. The n-hexane extract was fractioned by simple column chromatography. Eight terpenes were annotated in collection 6 (C6) by LC-QTOF-MS using a gradient elution and Electrospray Ionization (ESI) in positive ion mode: 1) Gibberellin A15, 2) farfugin A, 3) dehydromyodesmone, 4) eremopetasitenin A1, 5) hydroxyisonobilin, 6) anhydrocinnzeylanine, 7) nigakilactone H and 8) taxodione. On the other hand, C6 showed a concentration-dependent cytotoxic effect on cancer cell lines MCF-7 (Emax = 74.69 ± 6.19 % and IC50 = 6.31 μg/mL), MDA-MB-231 (Emax = 79.28 ± 12.12 % and IC50 = 124.21 μg/mL), and SiHa (Emax = 82.96 ± 6.02 % and IC50 = 124.31 μg/mL). The C6 did not show a cytotoxic effect against DU-145 and non-cancerous cells from the mammary glands MCF-10A. These results indicate cytotoxic specificity on cancer cell lines and support the hypothesis that terpenes identified in E. mexicana must be investigated and developed for non-clinical and clinical trials as potential anti-cancer drugs.

Optimized analytical strategy based on high-resolution mass spectrometry for unveiling associations between long-term chemical exposome in hair and Alzheimer’s disease

Exposure to environmental pollutants or contaminants is correlated with detrimental effects on human health, such as neurodegenerative diseases. Adopting hair as a biological matrix for biomonitoring is a significant innovation, since it can reflect the long-term chemical exposome, spanning months to years. However, only a limited number of studies have developed analytical strategies for profiling the chemical exposome in this heterogeneous biological matrix. In this study, a systematic investigation of the chemical extraction procedure from human hair was conducted, using a design of experiments and a high-resolution mass spectrometry (HRMS)-based suspect screening approach. The PlackettBurman (PB) design was applied to identify the significant variables influencing the number of detected features. Then, a central composite design was implemented to optimize the levels of each identified significant variable. Under the optimal conditions—15-minute pulverization, 25 mg of hair weight, 40 min of sonication, and a sonication temperature of 35 °C—approximately 32,000 and 15,000 aligned features were detected in positive and negative ion modes, respectively. This optimized analytical procedure was applied to hair samples from patients with Alzheimer's disease (AD) and individuals with normal cognitive function. Overall, 307 chemicals were identified using the suspect screening approach, with 37 chemicals differentiating patients with AD from controls. This study not only optimized an analytical procedure for characterizing the long-term chemical exposome in human hair but also explored the associations between AD and environmental factors.

Unraveling gender-specific lipids and flavor volatiles in giant salamander (Andrias davidianus) livers via lipidomics and GC-IMS

To uncover the relationships between lipid components and flavor volatiles, distinctness in lipid components and odor substances in giant salamander livers of different genders were comparatively characterized through UPLC-Q Exactive-MS lipidomics and gas chromatography-ion migration spectrometry (GC-IMS). A total of 2171 and 974 lipid metabolites were detected in positive and negative ion modes, respectively. Triglycerides (TG) and phosphatidylcholines (PC) are the most abundant types of lipids. TG level in male livers was higher than that in female livers (P < 0.05), whereas PC level showed no marked variation (P > 0.05). Additionally, a total of 51 volatile components were detected through GC-IMS. Ketones (42.18 % ∼ 45.44 %) and alcohols (24.19 % ∼ 26.50 %) were the predominant categories, and their relative contents were higher in female livers. Finally, 30 differential lipid metabolites and 12 differential odor substances were screened and could be used as distinguishing labels in giant salamander livers of different genders. Correlation analysis indicated that PS(36:2e), TG(48:13), ZyE(37:6), and ZyE(33:6) correlated positively with 3-methyl butanal, 3-hydroxy-2-butanone, and 2-methyl-1-propanol (P < 0.05), but adversely linked with 1-penten-3-one, and 1-octen-3-one (P < 0.01). By three-fold cross-validation, prediction accuracies of these differential lipids and volatile compounds for gender recognition based on random forest model were 100 % and 92 %, respectively. These findings might not only add knowledge on lipid and volatile profiles in giant salamander livers as affected by genders, but also provide clues for their gender recognition.

High-Resolution Drift Tube Ion Mobility Spectrometer with Ultra-Fast Polarity Switching.

Besides safety and security applications, ion mobility spectrometry (IMS) is increasingly used in other fields such as medicine, environmental monitoring and food quality analysis. However, some applications require gas chromatographic separation before analysis by IMS. Furthermore, different compounds in the sample may form positive or negative ions during ionization and therefore simultaneous detection of both ion polarities is highly beneficial to avoid two chromatographic runs of the same sample. This can be achieved by ultra-fast polarity switching of a single drift tube IMS, allowing for quasi-simultaneous detection of both ion polarities. By using a ramped aperture voltage during the switching process, we overcome the issue of excessive displacement currents at the detector during polarity switching, which usually lead to overdriving the output signal of the high-gain transimpedance amplifier. Furthermore, mechanical aperture grid oscillations caused by polarity switching were also reduced through the ramped aperture voltage. This enables a polarity switching time of only 7 ms at a drift voltage of 8 kV and a drift length of 103 mm, leading to a high resolving power of RP = 117. Requiring 50 ms to acquire a pair of positive and negative spectrum, the IMS achieves an acquisition rate of 20 Hz. It reaches limits of detection of 20 pptv for dimethyl methylphosphonate and 40 pptv for methyl salicylate. For demonstration, different hop varieties were investigated and could be clearly differentiated by considering both, the positive and negative spectra.