Electrospray Ionization Source Research Articles

Analysis of Pesticide Residues on Fruit Using Swab Spray Ionization Mass Spectrometry.

The vast quantity and high variety of pesticides globally used in agriculture entails considerable risks for the environment and requires ensuring the safety of food products. Therefore, powerful analytical tools are needed to acquire qualitative and quantitative data for monitoring pesticide residues. The development of ambient ionization mass spectrometry methods in the past two decades has demonstrated numerous ways to generate ions under atmospheric conditions and simultaneously to reduce the need for extended sample preparation and circumvent chromatographic separation prior to mass analysis. Swab spray ionization enables the generation of ions directly from swabs via the application of high voltage and solvent flow. In this study, swab sampling of fruit surfaces and subsequent ionization directly from the swab in a modified electrospray ion source was employed for the screening and quantitation of pesticide residues. Aspects regarding sample collection, sampling efficacy on different surfaces, and swab background are discussed. The effect of solvent composition on pesticide-sodium adduct formation and the suppression of ionization by the background matrix have been investigated. Furthermore, a novel approach for the quantitation of pesticide residues based on depletion curve areas is presented. It is demonstrated that swab spray ionization is an effective and quick method for spectral library-based identification and the quantitative analysis of polar contact pesticide residues on food.

A Pharmacokinetic Study of Sixteen Major Bioactive Components of Jinshui-Huanxian Granules in Pulmonary Fibrosis Model and Control Rats Using Orbitrap Fusion Mass Spectrometry.

Jinshui-Huanxian granules (JHGs), a Chinese herbal compound prescription, have shown a therapeutic effect in reducing lung tissue damage, improving the degree of pulmonary fibrosis, replenishing lungs and kidneys, relieving cough and asthma, reducing phlegm, and activating blood circulation. However, these active compounds' pharmacokinetics and metabolic processes were unclear. This study aimed to compare the pharmacokinetics, reveal the metabolic dynamic changes, and obtain the basic pharmacokinetic parameters of 16 main bioactive compounds after intragastric administration of JHGs in control and pulmonary fibrosis (PF) model rats by using Orbitrap Fusion MS. After administration of JHGs, the rat plasma was collected at different times. Pretreating the plasma sample with methanol and internal standard (IS) solution carbamazepine (CBZ), and it was then applied to a C18 column by setting gradient elution with a mobile phase consisting of methanol 0.1% formic acid aqueous solution. Detection was performed on an electrospray ionization source (ESI), and the scanning mode was SIM. Pharmacokinetic parameters were analyzed according to the different analytes' concentrations in plasma. The matrix effect was within the range of 79.01-110.90%, the extraction recovery rate was 80.37-102.72%, the intra-day and inter-day precision relative standard deviation (RSD) was less than 7.76%, and the stability was good, which met the requirements of biological sample testing. The method was validated (r ≥ 0.9955) and applied to compare the pharmacokinetic profiles of the control group and PF model group after intragastric administration of the JHGs. The 16 analytes exhibited different pharmacokinetic behaviors in vivo. In the pathological state of the PF model, most of the components were more favorable for metabolism and absorption, and it was more meaningful to study the pharmacokinetics. Above all, this study provided an essential reference for exploring the mechanism of action of JHGs and guided clinical medication as well.

A fully validated method for simultaneous determination of icotinib, osimertinib, gefitinib and O-desmethyl gefitinib in human plasma using UPLC-MS/MS for therapeutic drug monitoring

Background and aimsA few researches have reported the exposure-efficacy/toxicity relationships of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs). On account of the large interpatient pharmacokinetic variability, therapeutic drug monitoring (TDM) seems promising for optimizing dosage regimen and improving treatment efficacy and safety. Therefore, a rapid and convenient ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of icotinib, osimertinib, gefitinib and O-demesthyl gefitinib in human plasma for TDM. Materials and methodsIcotinib-D4 and osimertinib-13CD3 were used as the internal standards (ISs). The samples were prepared by protein precipitation using acetonitrile. Chromatographic separation was achieved on a 40 ℃ Shimadzu Shim-pack Scepter C18–120 column (2.1 ×50 mm, 3.0 µm, Japan) by a Shimadzu 30 A solvent management system. Detection was carried out using a Shimadzu LC-MS 8050CL triple quadrupole mass spectrometer coupled with an electrospray ionization source in positive mode. ResultsThis analytical method was fully validated with selectivity, carry-over, linearity, lower limit of quantification, accuracy (from 92.68% to 106.62%) and precision (intra- and inter-day coefficients of variation ranged from 0.92% to 9.85%), matrix effect, extraction recovery, stability and dilution integrity. The calibration curves were developed to be within the concentration ranges of 200–4000 ng/mL for icotinib, 50–1000 ng/mL for osimertinib, gefitinib and O-desmethyl gefitinib in human plasma which meet the needs of routine TDM. ConclusionsThe proposed method was used in 100 patients with non-small cell lung cancer for monitoring plasma concentration of the mentioned EGFR-TKIs. The trough concentrations of ICO were distributed between 226.42 ng/mL and 3853.36 ng/mL, peak concentrations were between 609.20 ng/mL and 2191.54 ng/mL. The trough concentrations of OSI were distributed between 110.48 ng/mL and 1183.13 ng/mL. The trough concentrations of GEF were distributed between 117.71 ng/mL and 582.74 ng/mL, while DeGEF was distributed from 76.21 ng/mL to 1939.83 ng/mL with two less than 20 ng/mL. The results of therapeutic drug monitoring aimed to investigate exposure-efficacy/toxicity relationship and improve the efficacy and safety of targeted therapies.

Determination of nine organic amine compounds in CO2 absorption liquid by hydrophilic interaction liquid chromatography-electrostatic field orbitrap high resolution mass spectrometry

Carbon dioxide (CO2) absorption and capture is an effective measure to achieve the "dual carbon" goal of carbon peak and carbon neutrality in China. Organic amine compounds are widely used in the industrial separation and recovery of CO2. Thus, the establishment of analytical methods for organic amine compounds is of great significance for the research and development of carbon capture and storage (CCS) technology and carbon capture, utilization and storage (CCUS) technology. In this study, a method was developed for the determination of nine organic amine compounds in CO2 absorption liquid by hydrophilic interaction liquid chromatography (HILIC)-electrostatic field orbitrap high resolution mass spectrometry. The sample was diluted with water and filtered through a 0.22 μm nylon membrane before sampling and analysis. An Accucore HILIC column (100 mm×2.1 mm, 2.6 μm) was used for separation at 30 ℃. Gradient elution was conducted using 90% acetonitrile aqueous solution containing 5 mmol/L ammonium formate and 0.1% formic acid as mobile phase A and 10% acetonitrile aqueous solution containing 5 mmol/L ammonium formate and 0.1% formic acid as mobile phase B. Determination was performed using an electrospray ion source (ESI) in the positive ion mode. The quantitative analysis was carried out by standard addition method. The chromatographic retention performance of different chromatographic columns and the influence of different mobile phases on the separation of the organic amine compounds were compared, and the method was validated. The results showed that the linear ranges of the nine organic amine compounds were 0.04-25000 ng/mL with the linear correlation coefficients (R2) greater than 0.9910. The limits of detection (LODs) of the method were in the range of 0.0004-0.0080 ng/mL, and the limits of quantification (LOQs) of the method were in the range of 0.0035-0.0400 ng/mL. The average recoveries of the method ranged from 85.30% to 104.26% with relative standard deviations (RSDs) of 0.04%-7.95% at the spiked levels of 1, 1.5 and 3 times sample concentration. The established method was applied to detect the absorption waste liquid of a cement plant, and nine organic amine compounds could be effectively detected. The stability of the actual sample was tested, and the RSDs were 0.10%-6.35% in 48 h at 4 ℃. The method is sensitive, rapid and accurate for the determination of the nine organic amine compounds in industrial waste water. It can provide reference for the detection of organic amine compounds, and provide strong technical support for the research and industrial application of CO2 capture technology.

Quantification of hetero-cyclic amines from different categories of braised beef by optimized UPLC-TQ-XS/ESI method.

This research work has developed and optimized a sensitive analytical method for separation and quantification of heterocyclic amines (HCAs) mainly including PhIP, Harman, Norharman, IQ, MeIQ, AαC, MeAαC and Trp-P-2 by optimizing UPLC-TQ-XS using electrospray ionization source (ESI+) on ACQUITY UPLC® BEH C18 column in <7min, from braised beef sample matrix. Meanwhile, modified HCAs extraction by modifying QuEChERS (quick, easy, cheap, efficient, rugged and safe) technique and revisited with solid phase extraction (SPE) for HCAs purification, instead using traditional QuEChERS salts. Moreover, optimized pH conditions of HCA extracts before purification, for better extraction recoveries. Furthermore, this method was validated in terms of method validation parameters. Lastly, simulation of real braised beef model provided the minimum formation of HCAs by optimizing cooking parameters and precursors in a cooking system. Therefore, this method could be applied simultaneously on braised beef matrix either marketed or home cooked for HCAs analysis.

Antitumor and antibacterial activity of metabolites of endophytic Colletotrichum siamense isolated from coffee (Coffea arabica L. cv IAPAR-59).

Endophytic fungi produce a range of known metabolites and several others, not yet explored, which present important biological activities from the pharmaceutical and industrial perspective. Several studies have reported the diversity of endophytes in Coffea arabica plants, although few have been described in organic cultures. In the current paper, we describe the chemical profile of specialized metabolites in the ethyl acetate phase in a strain of the endophytic fungus Colletotrichum siamense associated with coffee (Coffea arabica L.) (Rubiaceae) and its potential against tumor cells and bacteria of medical and food importance. Cytotoxicity assays in tumor cells MCF-7 and HepG2/C3A were performed by MTT and microdilution in broth to evaluate the antibacterial action of metabolic extract. The antiproliferative assay showed promising results after 24h of treatment, with 50% injunction concentrations for the two cell types. UHPLC-MS/MS analyses with an electrospray ionization source were used to analyze the extracts and identify compounds of species Colletotrichum siamense, which is still little explored as a source of active metabolites. Many of these compounds observed in the endophytic need to be chemically synthesized in industry, at high costs, while production by the fungus becomes a chemically and economically more viable alternative. Pyrocatechol, gentisyl alcohol, and alpha-linolenic acid, associated with different mechanisms of action against tumor cells, were detected among the main compounds. The extract of the endophytic fungus Colletotrichum siamense presented several compounds with pharmacological potential and antibacterial activity, corroborating its potential in biotechnological applications.

A 3D-printed sub-atmospheric pressure electrospray ionization source for robust, facile, and flexible mass spectrometry analysis.

The operation and performance of electrospray ionization (ESI) is affected by the surrounding environment. In this study, a compact sub-atmospheric pressure ESI (SAP-ESI) source was designed and fabricated using the 3D printing method. This source has a simple structure and is easy to operate, as the sample solution and auxiliary gas are continuously sucked into the source through the pressure difference. The compact and enclosed ionization chamber can reduce the fluctuation of the surrounding gas flow to ensure a remarkably stable (< 3%) electrospray. Moreover, the source can offer variable SAP conditions for ESI analysis. The yield of analyte ions increases with decreasing pressure, while the production of background ions is suppressed under these conditions. In the analysis of protein samples, SAP-ESI can increase the yield and charge state of ions, which may be due to the reduction of proton transfer between charged proteins and surrounding gas. The SAP-ESI source was then used to continuously monitor the extract aqueous solution of tea leaves, and to detect the carbendazim residues on the apple surface by coupling with the liquid extraction surface analysis technique. Experimental results demonstrate that the developed SAP-ESI is a stable, practical, and versatile ionization technique.

(Invited) Ionic Liquid Electrospray Ion Sources for Space Propulsion

The number of microspacecraft launched has significantly increased since 2013, and more than 300 nano/microsatellites (< 50 kg) were launched in 2017. Although some microspacecraft already have a propulsion system, a commonly used propulsion system is a cold-gas thruster, which has a low delta-v (a few 10s of m/s), and thus, high delta-v (> 1 km/s) thrusters are required for more advanced missions. One of the candidates for such thrusters is ion thrusters, which were already mounted on two 50 kg-class microsatellites and successfully operated in space. However, it is not easy to miniaturize ion thrusters so that they can be mounted on even 10 kg-class nanosatellites unless high-pressure gas-feeding systems are removed. Moreover, ion thrusters require electron sources to neutralize ion beams, which consume additional propellants and power. Since most recently launched microspacecraft are less than 10 kg, more compact thrusters are required. Ionic liquid electrospray ion sources are attractive devices for such electric propulsion, especially for microspacecraft. Electrospray thrusters typically consist of many emitters, an extractor electrode, and an accelerator electrode optionally. When a high voltage between the emitter and the extractor is applied, the ionic liquid is transported to the emitter tips, and a strong electric field deforms the ionic liquid into a conical shape known as a Taylor cone. When the force of the electric field is stronger than the surface tension pressure of the ionic liquid, ions evaporate directly from the liquid surface. The extracted ions are then accelerated by the potential difference between the emitter and extractor to produce the thrust. Since the ionic liquid is composed of only cations and anions without solvent, its vapor pressure is negligible; therefore, it can exist in the liquid phase in vacuum, simplifying the propellant feed system and reducing the size of the entire propulsion system. Moreover, the direct acceleration of ions without discharges can be possible, and no neutralizers are required, which also contributes to the power and size reduction together with high efficiency. The key component of electrospray thrusters is the emitter, where there are typically three types of structures: externally-wetted (or needle-shaped), internally-wetted (or capillary), and porous ones. Each has ion emission characteristics depending on the structure. Here, we have fabricated these three types of emitter structures with a wide range of scale: 1 to 100 micrometers. Using these emitters, we have conducted ion emission experiments and beam diagnostics. We obtained a high current density over a few 10 mA/cm2 with 1-micrometer scale emitters, a high current of approximately 1 mA with porous emitters, and a high efficiency with externally-wetted emitters. The emitter structures as mentioned earlier and experimental results will be presented at the conference site.

GC-MS and LC-MS/MS Analysis of Secondary Metabolites in the Methanolic Extract of Uncaria callophylla Blume ex Korth. Stems

Uncaria callophylla Blume ex Korth. is a wild plant species belonging to the Rubiaceae family. These plants thrive in the peat swamp forest of Kalimantan, Indonesia. The stems of Uncaria callophylla have been used by the Dayak Ngaju tribe to treat various diseases and to restore stamina while they work in the forest. The present study was conducted to identify the secondary metabolites in the methanolic extract of Uncaria callohylla stems to increase the knowledge about this plant and its potential in medicinal applications and drug discovery. The analysis was conducted using GC-MS and LC-MS/MS. GC-MS analysis was performed with the Agilent Technologies 7890 Gas Chromatography equipped with an Auto Sampler and 5975 Mass Selective Detector. The LC-MS analysis was carried out in the C18 column of the Waters Acquity UPLC system. MS analysis was performed with an electrospray ionization source (ESI) in positive and negative ion modes, and the compounds were identified using a UNIFI data processor with a mass spectrum library of natural active substances from the Waters Traditional Medical Scientific Library database based on UPLC/QTof MSE Data Acquisition. GC-MS analysis revealed the presence of 24 peaks, and nine of them showed quality 90% or higher, namely n-Hexadecanoic acid (16.63%), 1,3,7-Trimethyl-3,7-Dihydro-1H-Purine-2,6-Dione (13.07%), Hexadecanoic Acid, Methyl Ester; 1,2-Benzenedicarboxylic Acid, Diethyl Ester; 9,12-Octadecadienoic Acid, Methyl Ester; Methyl 14-Methylheptadecanoate; (9E,12E)-9,12-Octadecadienoic Acid; Z, E-3,13-Octadecadien-1-o1; and 2,6,10,14,18,22-Tetracosahexaene, 2,6,10,15,19,23-hexanethyl-, (all-E)-. LC-MS/MS analysis revealed the presence of five compounds, namely Arecatannin A1, Sweroside_2, Uncarine A, Epianhydrobelachinal, and Betulonic acid. All the secondary metabolites identified from GC-MS and LC-MS/MS analysis have biological activity, which indicates their medicinal potencies. From the result, it can be concluded that Uncaria callophylla stem methanolic extract contains various bioactive compounds justifies its traditional use, and therefore it can be developed further for new drug discovery.

Development and validation of an HPLC-MS/MS assay for the quantitative analysis of remimazolam in critically ill patients

Remimazolam is a novel benzodiazepine which is commonly used in procedural sedation, but its pharmacokinetics in critically ill patients have not yet been unequivocally clarified. A high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method was established and validated for the determination of the remimazolam concentration in human plasma. The plasma sample extraction method was protein precipitation. A triple quadrupole mass spectrometer equipped with an electrospray ionization source and multiple reaction monitoring was used for mass spectrometry analysis. The analytes were isolated on an ACQUITY UPLC BEH C18 column with the mobile phase A (10 mM ammonium acetate in water containing 0.2% formic acid) and mobile phase B (acetonitrile) under a gradient program. The retention time of the analyte and IS were 2.0 and 1.4 min, respectively. The linear range for quantitative analysis of remimazolam was 1.0–1000 ng/mL and the extraction recovery rate was 97.3%–99.3%. According to the Chinese Pharmacopoeia and the ICH Harmonized Guidelines for Biological Analysis Method Validation, this approach has been validated in terms of selectivity, accuracy, precision, carryover, dilution integrity, matrix effects and stability. In a population pharmacokinetic study of remimazolam that targeted patients in intensive care units, the HPLC-MS/MS method was successfully applied to the quantitative measurement of remimazolam concentrations in human plasma. This method has the advantages of simplicity of operation, reliability, and sensitivity.

Determination and Chemotaxonomic Analysis of Lanostane Triterpenoids in the Mycelia of Ganoderma spp. Using Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry (I).

A comprehensive and sensitive method combining ultra-performance liquid chromatography with tandem mass spectrometry was developed for the quantification of characteristic triterpenoids in Ganoderma mycelia. Eight ganoderic acids previously isolated from the mycelia of Ganoderma lingzhi were separated with a binary mobile phase on a reversed-phase C18 column. A triple quadrupole mass spectrometer equipped with an electrospray ionization source was used as the detector in the negative ion mode. Identification and quantitation of target ganoderic acids were accomplished using the dynamic multiple reaction monitoring mode. The developed method was validated in terms of linearity, precision, accuracy, stability, and recovery. The method was first applied to quantify the contents of eight ganoderic acids in the mycelia of G. lingzhi at different times to determine the optimum fermentation conditions. Subsequently, the distribution of triterpenoids and the contents of eight ganoderic acids in sixteen different Ganoderma species were investigated. The results indicated that UV chromatography combined with dynamic multiple reaction monitoring quantification was an effective chemotaxonomy method for Ganoderma species identification. This study also provided a helpful analytical methodology for both scientific and industrial applications in the quality control of Ganoderma triterpenoids.

A Fast LC-MS/MS Methodology for Estimating Savolitinib in Human Liver Microsomes: Assessment of Metabolic Stability Using In Vitro Metabolic Incubation and In Silico Software Analysis

Savolitinib (Orpathys®), was developed by (HUTCHMED (Shanghai, China) and, AstraZeneca (Gaithersburg, Maryland, USA), is an inhibitor of the c-Met receptor tyrosine kinase that is orally bioavailable. It was designed for the treatment of pillary and clear-cell renal-cell carcinoma (RCC), colorectal cancer, gastric cancer, and metastatic non-small-cell lung cancer (NSCLC). The current work aimed to develop a rapid, specific, green, and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) methodology for estimating savolitinib (SVB) in human liver microsomes (HLMs) with application to an in vitro metabolic stability assessment of SVB in HLMs. The validation steps of the current LC-MS/MS methodology in the HLMs were carried out following US FDA bioanalytical method validation guidelines including sensitivity, selectivity, linearity, accuracy, stability, precision, extraction recovery, and matrix effect. SVB and olmutinib (OLM) were chromatographically separated on an Eclipse Plus C8 column using an isocratic mobile phase. SVB parent ions were generated using the positive mode of an electrospray ionization (ESI) source. SVB daughter ions were detected and quantified using the multiple reaction monitoring (MRM) mode of a triple quadrupole mass analyser. The constructed SVB calibration curve showed linearity over the range from 1 to 3000 ng/mL. The interday and intraday accuracy and precision of the developed LC-MS/MS analytical methodology were −6.67%–4.11% and −0.51%–8.75%, respectively. A lower limit of quantification (LLOQ) of 0.87 ng/mL confirmed the sensitivity of the established method. Furthermore, the eco-scale methodology using the in silico AGREE software was used for the greenness assessment of the current LC-MS/MS method, and the outcomes showed that the established method was very eco-friendly. The intrinsic clearance (Clint) and in vitro half-life (t1/2) of SVB were 33.05 mL/min/kg and 24.54 min, respectively. SVB exhibited a moderate extraction ratio. The current study is the first to establish and validate LC-MS/MS for estimating SVB and assessing the metabolic stability of SVB.

Molecular characteristics and potential source of urban PM2.5-bound water-soluble organic matter in Shanghai during springtime

Water-soluble organic matter (WSOM) is complicated component in atmospheric fine particulate matter (PM2.5) and has attracted increasing attentions due to their effects on air quality, climate change, and human health. In this study, the molecular characteristics and potential source of PM2.5-bound water-soluble organic matter in Shanghai during springtime were investigated using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) coupled with electrospray ionization (ESI) source in negative ion mode. A total of 2537 monoisotopic molecular formulas were assigned in WSOM, and CHO, CHON, CHOS and CHNOS compounds were main components. Highly unsaturated CHO (DBE = 5.01−7.30) and CHON (DBE = 3.66−10.1) compounds were found in good weather days, while the highly oxygenated multifunctional CHOS compounds (O/C = 0.50−0.88) increased in slightly polluted days. Van Krevelen diagrams revealed that carbohydrates, lignin species, and protein species were the most abundant classes in all samples, which their relative abundance accounted for 81.8%. Comparison of our results with previously published data on atmospheric PM2.5 indicated that the biogenic aerosol and local industrial emission presented a larger impact on molecular compositions of WSOM in this region. These findings present a comprehensive overview of WSOM in Shanghai, which helps to understand their characteristics and sources.

Petroleomics by design of experiments in ESI(±)FT-ICR MS analysis

The Fourier Transform Ion Cyclotron Resonance mass spectrometer (FT-ICR MS) is an efficient and widely used analytical instrument for characterizing complex organic mixtures at the molecular level. The Electrospray ionization (ESI) source is commonly used for identifying heteroatomic compounds (N, O, S) in crude oil. The high complexity of the sample provides a wealth of information, and therefore, processing and visualization programs are used to facilitate data interpretation. Several experimental configurations of parameters exist for the acquisition of ESI(+)FT-ICR MS and ESI(-)FT-ICR MS of crude oils. In this context, the design of experiments can help obtain optimal test conditions. The objective of this work was to identify the most significant experimental parameters among the 11 available (concentration, skimmer, time of flight (TOF), flow rate, ion accumulation time (IAT), accumulated scans (scans), dry temperature, capillary, dry gas, nebulizer, and collision voltage (CV)) for the acquisition of ESI(±)FT-ICR MS in Petroleomics using design of experiments by Plackett Burman and full design. Global desirability was used as a response parameter obtained from MS data (resolution, signal-to-noise ratio, signal-to-charge ratio signal with highest absolute intensity, total signals, low mass error, and high mass error). Additionally, responses from the mass spectra processing program were also used (the number of molecular formulas, molecular formulas of the majority class, average error, assignment percentage, amount of DBE in the plot of DBE versus carbon number (CN), and the relationship between the number of zero intensities and the number of DBE values in the plot of DBE versus CN). The study found that concentration and flow rate were the most significant experimental parameters for ESI(+), while for ESI(-), TOF and CV were the most significant experimental parameters. Lower concentration (0.1–0.5 mg/mL) and higher flowrate (5–6 µL/min) improved the desirability by ESI(+), higher values of CV (50 V) improved the desirability by ESI(-) for crude oil analysis.

Non-targeted Metabolomics Analysis Reveals Distinct Metabolic Profiles Between Positive and Negative Emotional Tears of Humans: A Preliminary Study.

Background Basal, reflex, and emotional tears differ in chemical components. It is not yet known whether chemical differences exist in tears of different emotions. We investigated the biochemical basis of emotional tears by performing non-targeted metabolomics analyses of positive and negative emotional tears of humans. Methods Samples of reflex, negative, and positive emotional tears were obtained from 12 healthy college participants (11 females and one male). Untargeted metabolomics was performed to identify metabolites in different types of tears. The differentially altered metabolites were screened and assessed using univariate and multivariate analyses. Results The orthogonal partial least squares discriminant analysis model showed that reflex, negative, and positive emotional tears were clearly separated. A total of 133 significantly differentially expressed metabolites of electrospray ionization source (ESI-) mode were identified between negative and positive emotional tears. The top 50 differentially expressed metabolites between negative and positive emotional tears were highly correlated. Pathway analysis revealed that secretion of negative emotional tears was associated with some synapses in the brain, regulation of a series of endocrine hormones, including the estrogen signaling pathway, and inflammation activities, while secretion of positive emotional tears was correlated with biotin and caffeine metabolism. Conclusions It is indicated that metabolic profiles of reflex, positive, and negative emotional tears of humans are distinct, and secretion of the tears involves distinct biological activities. Therefore, we present a chemical method for detecting human emotions, which may become a powerful tool for the diagnosis of mental diseases and the identification of fake tears.

Development of a UPLC-MS/MS Assay for the Quantitative Determination of Capecitabine, 5'-deoxy-5-fluorocytidine (5'-dFCR), 5'-deoxy-5-fluorouridine (5'-dFUR), 5'-fluorouracil (5-FU), and α-fluoro-β-alanine (FBAL).

Capecitabine is an anticancer agent and is the oral prodrug of 5-fluorouracil (5-FU). In this study, an ultra-high performance liquid chromatography coupled to turbo ion spray tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to quantify capecitabine and its metabolites including 5'-deoxy-5-fluorocytidine (5'-dFCR), 5'-deoxy-5-fluorouridine (5'-dFUR), 5-FU, and fluoro-β-alanine (FBAL) in lithium heparinized human plasma. Analytes were extracted by protein precipitation, chromatographically separated by Acquity UPLC HSS T3 column with gradient elution, and analyzed with a tandem mass spectrometer equipped with an electrospray ionization source. Capecitabine and 5'-dFCR were quantified in positive ion mode and 5'-dFUR, 5-FU, and FBAL were quantified in negative ion mode. The total chromatographic run time was 9 min. Stable isotopically labeled internal standards were used for all analytes. The assay was validated over the range from 25.0 to 2,500 ng/mL for capecitabine, 10.0 to 1,000 ng/mL for 5'-dFCR, 5'-dFUR, and 5-FU and 50 to 5,000 ng/ mL for FBAL in human plasma. Validation results have shown the developed assay allows for reliable quantitative analysis of capecitabine, 5'-dFCR, 5'-dFUR, 5-FU, and FBAL in plasma samples. Capecitabine is an anticancer agent and is the oral prodrug of 5-fluorouracil (5-FU). In this study, an ultra-high performance liquid chromatography coupled to turbo ion spray tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to quantify capecitabine and its metabolites including 5'-deoxy-5-fluorocytidine (5'-dFCR), 5'-deoxy-5-fluorouridine (5'-dFUR), 5-FU, and fluoro-β-alanine (FBAL) in lithium heparinized human plasma. Analytes were extracted by protein precipitation, chromatographically separated by Acquity UPLC HSS T3 column with gradient elution, and analyzed with a tandem mass spectrometer equipped with an electrospray ionization source. Capecitabine and 5'-dFCR were quantified in positive ion mode and 5'-dFUR, 5-FU, and FBAL were quantified in negative ion mode. The total chromatographic run time was 9 min. Stable isotopically labeled internal standards were used for all analytes. The assay was validated over the range from 25.0 to 2,500 ng/mL for capecitabine, 10.0 to 1,000 ng/mL for 5'-dFCR, 5'-dFUR, and 5-FU and 50 to 5,000 ng/ mL for FBAL in human plasma. Validation results have shown the developed assay allows for reliable quantitative analysis of capecitabine, 5'-dFCR, 5'-dFUR, 5-FU, and FBAL in plasma samples.

Capillary self-aspirating electrospray ionization (CSESI) for convenient and versatile mass spectrometry analysis

Electrospray ionization (ESI) is one of the most widely used ionization techniques, and its simplification can benefit many interested users. In this study, sample introduction by capillary action was studied and used to develop a simple ESI source called capillary self-aspirating electrospray ionization (CSESI). A conventional CSESI source requires only a common capillary of appropriate diameter in addition to the support of high voltage (HV). No pumps and sample loading is needed because the solution can spontaneously climb across the capillary by capillary action. With the proper modification of the glass capillary, the operation of CSESI can be further simplified and efficient. Specifically, cold plasma processing of the capillary creates a more hydrophilic surface that can facilitate sample introduction. Moreover, sputtering a thin platinum layer on the capillary tip makes the application of HV more convenient, and it also eliminates the influence of air bubbles in the capillary to ensure a sustained and stable electrospray. Overall, CSESI exhibits multiple desirable features such as simple structure, self-aspiration ability, low sample consumption, and inherent physical filtration capability. Apart from the routine ESI-MS analysis, it has also been applied in real-time monitoring of the oxidative dimerization of 8-methyl-1,2,3,4-tetrahydroquinoline, as well as direct analysis of muddy soil solutions without pretreatment.

Development and validation of an LC-MS/MS method for simultaneous determination of EVT201 and its five metabolites in human plasma: Application to a clinical study in Chinese healthy subjects

EVT201 is a partial GABAA receptor agonist, which inhibits nervous system to treat insomnia. EVT201 can form a variety of metabolites in vivo including Ro46–1927, Ro18–5528, Ro40–9970, Ro66–9196 and Ro66–5448. This study developed a simple method to realize the simultaneous determination of EVT201 and its five metabolites by HPLC-MS/MS with an electrospray ion source (ESI). The deuterium substitute of EVT201 was chosen as the internal standard and the multiple reaction monitoring (MRM) was used for the quantification. The separation of the six compounds was accomplished with an ACE Excel 3 AQ column (50 × 2.1 mm, 3 µm, ACE). The process of protein precipitating-transferring-nitrogen blowing-reconstituting was adopted for the sample pretreatment. This method was successfully validated according to the FDA guidance. Calibration curves were linear over the concentration range of 0.100–100 ng/mL for EVT201, 0.0300–30.0 ng/mL for Ro46–1927, 0.0600–6.00 ng/mL for Ro18–5528, 0.0200–4.00 ng/mL for Ro40–9970, 0.100–20.0 ng/mL for Ro66–9196 and 0.100–20.0 ng/mL for Ro66–5448. The intra-run and inter-run precisions and accuracies were all within 14.5%. This fully validated method was successfully applied to a clinical pharmacokinetic study of EVT201 and its five metabolites in Chinese healthy subjects after the single (2.5 mg and 5 mg, N = 12) and multiple dose (2.5 mg, N = 13) administration of EVT201 capsules. The test results of 2.5 mg dose group showed that for EVT201, Ro46–1927, Ro18–5528, Ro40–9970, Ro66–9196 and Ro66–5448, the Cmax values (ng/mL) were 39.2 ± 9.2, 10.3 ± 1.4, 0.218 ± 0.044, 0.128 ± 0.051, 7.01 ± 1.51, 8.73 ± 3.69, respectively; the AUC0−t values (h·ng/mL) were 231 ± 79, 143 ± 72, 10.9 ± 2.1, 1.84 ± 0.78, 55.9 ± 18.7, 135 ± 40 respectively. For EVT201, Ro46–1927, Ro66–5528, Ro66–9196 and Ro40–5448, the results of Cmax and AUC0−t proved that the five compounds showed linear pharmacokinetic profile over the dose ranges of 2.5 mg to 5 mg. Meanwhile, it is the first report to evaluate the pharmacokinetic characteristics of Ro40–9970, Ro66–9196 and Ro66–5448 in human plasma. It provided meaningful parameters for the safety and tolerability evaluation of EVT201 capsules in human.

Application to several suspected poisoning cases of a validated analytical method for the determination of muscarine in human biological matrices using liquid chromatography with high-resolution mass spectrometry detection.

Despite prevention efforts, many cases of mushroom poisoning are reported around the world every year. Among the different toxins implicated in these poisonings, muscarine may induce parasympathetic neurological damage. Muscarine poisonings are poorly reported in the current literature, implying a lack of available data on muscarine concentrations in human matrices. A validated liquid chromatography with high-resolution mass spectrometry detection (Orbitrap technology) method was developed to determine muscarine concentrations in human urine, plasma, and whole blood samples. Muscarine was determined using 100 μL of biological fluids, and precipitation was used for sample preparation. Liquid chromatography-mass spectrometry was performed using an Accucore Phenyl-X analytical column with the electrospray source in positive ion mode. Muscarine was quantitated in parallel reaction monitoring (PRM) mode with D9-muscarine as the internal standard. The method was validated successfully over the concentration range 0.1-100 μg/L for plasma and whole blood and 1-100 μg/L for urine, with acceptable precision and accuracy (<13.5%), including the lower limit of quantification. Ten real cases of suspected muscarine poisoning were successfully confirmed with this validated method. Muscarine concentrations in these cases ranged from 0.12 to 14 μg/L in whole blood, <LOQ to 43 μg/L in plasma, and <LOQ to 1537 μg/L in urine. This work provides a tool of choice for the diagnosis of muscarine poisoning when mushrooms are not available for identification, as well as the possibility of determining toxins in the blood, which is an important step toward understanding the pharmacokinetics of the mycotoxin.

Structural Elucidations of derivatized Sterols using Electrospray Ionization/Atmospheric Pressure Chemical Ionization-Quadrupole Ion Trap-Mass spectrometry

Free sterols are neutral molecules that are difficult to ionize by Electrospray Ionization (ESI) or Atmospheric Pressure Chemical Ionization (APCI). Therefore, in order to increase their ionization efficiency, sterols were converted into their corresponding picolinyl esters. In this study we examined the possibility of analyzing picolinyl ester of sterols derivatives using flow injection ESI-quadrupole ion trap (QIT) MS and APCI-QIT MS and we investigated their fragmentation pathways using low energy collision induced dissociation-tandem mass spectrometry (CID-MS2). This study also aimed to examine the possibility of using ESI-QIT MS3 to identify sterol isomers. The picolinyl esters readily formed protonated molecular ions ([M+H]+) in ESI and APCI sources except for the picolinyl ester of 7-dehydrocholesterol which was detected as the radical cation ion [M].+ using APCI-QIT MS. The ester bonds of picolinyl esters cleaved during CID MS2, resulting in diagnostic fragments corresponding to steryl cation moieties [M+H-C6H5NO2]+. The CID MS3 of [M+H]+ → [M+H-C6H5NO2]+ of picolinyl esters was found to be useful for structural elucidation and for distinguishing among steryl isomers.