Search

Rationale: Paper spray offers a rapid screening test without the need for sample preparation. The incomplete extraction of paper spray allows for further testing using more robust, selective and sensitive techniques such as liquid chromatography/mass spectrometry (LC/MS). Here we develop a two‐step process of paper spray followed by LC/MS to (1) rapidly screen a large number of samples and (2) confirm any disputed results. This demonstrates the applicability for testing medication adherence from a fingerprint. Methods: Following paper spray analysis, drugs of abuse samples were analysed using LC/MS. All analyses were completed using a Q Exactive™ Plus Orbitrap™ mass spectrometer. This two‐step procedure was applied to fingerprints collected from patients on a maintained dose of the antipsychotic drug quetiapine. Results: The extraction efficiency of paper spray for two drugs of abuse and metabolites was found to be between 15 and 35% (analyte dependent). For short acquisition times, the extraction efficiency was found to vary between replicates by less than 30%, enabling subsequent analysis by LC/MS. This two‐step process was then applied to fingerprints collected from two patients taking the antipsychotic drug quetiapine, which demonstrates how a negative screening result from paper spray can be resolved using LC/MS. Conclusions: We have shown for the first time the sequential analysis of the same sample using paper spray and LC/MS, as well as the detection of an antipsychotic drug from a fingerprint. We propose that this workflow may also be applied to any type of sample compatible with paper spray, and will be especially convenient where only one sample is available for analysis. [ABSTRACT FROM AUTHOR]

Measurements of organosulfates in ambient aerosols provide insight to the extent of secondary organic aerosol (SOA) formation from mixtures of biogenic gases and anthropogenic pollutants. Organosulfates have, however, proved analytically challenging to measure. This study presents a sensitive new analytical method for the quantification of organosulfates based upon ultra-performance liquid chromatography with negative electrospray ionization mass spectrometry (UPLC-ESI-MS/MS). The separation is based upon hydrophilic interaction liquid chromatography (HILIC) with an amide stationary phase that provides excellent retention of carboxy-organosulfate and methyltetrol-derived organosulfates. The method is validated using six model compounds: methyl sulfate, ethyl sulfate, benzyl sulfate, hydroxyacetone sulfate, lactic acid sulfate, and glycolic acid sulfate. A straight forward protocol for preparation of highly pure organosulfate potassium salts for use as quantification standards is presented. This highly efficient method of separating and quantifying organosulfates is used to evaluate the efficiency and precision of two methods of ambient PM2.5 sample extraction. Spike recoveries averaged 98±8% for extraction by sonication and 98±10% for extraction by rotary-shaking. Sonication was determined to be the superior method for its better precision. Analysis of ambient PM2.5 samples collected 10-11 July 2013 in Centreville, AL, USA during the Southeast Atmosphere Study (SAS) confirms the presence of hydroxyacetone sulfate in ambient aerosol for the first time. Glycolic acid sulfate was the most abundant compound measured (ranging 8-14 ngm-3), followed by hydroxyl acetone sulfate (2.7-5.8 ngm-3) and lactic acid sulfate (1.4-2.9 ngm-3). Trace amounts of methyl sulfate were detected, while ethyl sulfate and benzyl sulfate were not detected. Future research will focus on the development of additional organosulfates standards, expansion of this UPLC-MS/MS to include more target molecules, and the application of this method to assess temporal variations in organosulfates in ambient environments. [ABSTRACT FROM AUTHOR]

Complete heparin digestion with heparin lyase I and II results in a mixture of hexasaccharides and tetrasaccharides with 3‐O‐sulfo group‐containing glucosamine residues at their reducing ends. Because these tetrasaccharides are derived from antithrombin III‐binding sites of heparin, we examined whether this method could be applied to estimate the anticoagulant activity of heparin. Therefore, this paper presents a new low molecular weight heparin sample preparation method–chemical depolymerization. Qualitative analysis of the studied compounds and a comparison of their composition are an important contribution to the structural analysis of low molecular weight heparins, which has not been fully conducted so far. Qualitative on‐line liquid chromatography–mass spectrometric analysis of these resistant oligosaccharides is also described in this paper. [ABSTRACT FROM AUTHOR]

In this paper, the effect of isotope-labeled analogs on the liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) measurement was evaluated based on the comparison research of electrospray ionization responses (ESI) and matrix effect of melamine, C-melamine, C+N-melamine, and N-melamine. The isotope-labeled melamines had similar ionization efficiency with melamine in the electrospray ionization source, but the intensity of corresponding quantitative fragment ions had distinctive differences. Based on the density functional theory at the B3LYP/6-311+G** level, this phenomenon was explained very well. The rare cleavage pathways of melamine, which just could be exactly identified by N-labeled melamines, resulted in the difference of quantitative fragment ions between N-labeled melamines and melamine. The interaction of ESI response between melamine and isotope-labeled melamines was investigated using MRM monitor mode. N-labeled melamine had significant ion inter-suppression effect on melamine, while C-labeled melamine had little influence on melamine. Finally, the influence of different isotope-labeled melamines on the LC-IDMS result was evaluated using the IDMS correction factor ( θ). Taking the determination of melamine in milk powder as an example, the matrix effects of different isotope-labeled melamines and melamine had notable difference and the impact of this difference on the measurement results depended on the concentrations of analyte and matrix solution. It was worth noting that N-melamine exhibited significant ion suppression to melamine in matrix solution. The deviation of the results from IDMS method might reach 59% using N-melamine as internal standard in special matrix solution. [ABSTRACT FROM AUTHOR]

RATIONALE Detailed analysis of the literature results on the electrospray ionization mass spectrometry (ESI-MS) fragmentation of amoxicillin and ampicillin, and their comparison with our results, have revealed some incorrect suggestions or incomplete interpretations of mass spectra of these compounds. Therefore, this paper contains a comprehensive discussion devoted to the ESI-MS/MS of ampicillin and amoxicillin as well as their degradation products, namely products of hydrolysis and methanolysis. METHODS Electrospray ionization collision-induced dissociation tandem mass (ESI-CID-MS/MS) spectra and accurate mass measurements were made on a quadrupole time-of-flight (Q-tof) mass spectrometer. Hydrolysis of the antibiotics was performed by heating, for a few hours, their aqueous solutions adjusted to pH 10. Methanolysis of the antibiotics was performed by heating their methanol solutions for a few minutes. Additionally, mass spectra of isotope-labeled compounds were also obtained. RESULTS A number of fragment ions, previously wrongly interpreted or not interpreted, have been rationalized. For example, formation of an abundant fragment at m/z 208 originating from the protonated amoxicillin molecule (ion [ Amox + H]+) was previously rationalized as a result of breaking of two bonds of the β-lactam ring. We found that this fragment ion had to be formed by the loss of ammonia and breaking of three bonds of the bicyclic system. CONCLUSIONS The discussion presented enables a better understanding of the MS decompositions of amoxicillin and ampicillin as well as their degradation products. MS decomposition is used for the determinations of these compounds, when the so-called multiple-reaction monitoring is applied during liquid chromatography (LC)/ESI-MS analysis. Thus, better understanding of MS decompositions of the above compounds seems to be important. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a multi-class target screening method for the detection of 105 veterinary drug residues from 11 classes in milk using ultra-high performance liquid chromatography electrospray ionization quadrupole Orbitrap mass spectrometry (UHPLC/ESI Q-Orbitrap). The method is based on a non-target approach of full mass scan and multiplexing data-independent acquisition (Full MS/mDIA). The veterinary drugs include endectocides, fluoroquinolones, ionophores, macrolides, nitroimidazole, NSAIDs, β-lactams, penicillins, phenicols, sulfonamides, and tetracyclines. Veterinary drug residues were extracted from milk using a salting-out and solid-phase extraction (SOSPE) procedure, which entailed the precipitation of milk proteins by an extraction buffer (oxalic acid and EDTA, pH 3) and acetonitrile, a salting-out acetonitrile/water phase separation using ammonium sulfate, and solid-phase extraction for clean-up using polymeric reversed-phase sorbent cartridges. The Q-Orbitrap Full MS/dd-MS2 (data-dependent acquisition) was used to acquire product-ion spectra of individual veterinary drugs to build a compound database and a mass spectral library, whereas its Full MS/mDIA was utilized to acquire sample data from milk for target screening of veterinary drugs fortified at 1.0 or 10.0 μg/kg. The in-spectrum mass correction or solvent background lock-mass correction was used to minimize mass error when building the compound database from experimental dd-MS2 accurate mass data. Retention time alignment and response threshold adjustment were used to eliminate or reduce false negatives and/or false positive rates. The validated method was capable of screening 58% and 96% of 105 veterinary drugs at 1.0 and 10.0 μg/kg, respectively, without manually evaluating every compound during data processing, which will reduce the workload in routine practice. [ABSTRACT FROM AUTHOR]

Phytohormones are signaling and regulating metabolites involved in numerous plant processes, including growth, development, and responses to stress. Currently, the focus is on the analysis of multiple phytohormones in order to characterize crosstalk and hormone signaling networks. In this paper, representative phytohormones of the major classes are simultaneously determined in rice tissues by a generic solid-liquid extraction, followed by liquid chromatography and electrospray ionization high-resolution tandem mass spectrometry using a Q-Exactive™ instrument. After a thorough optimization of the sample preparation, the analytical method was fully validated toward the ultra-trace quantification of six a priori selected plant hormones using three scan modes of the quadrupole-Orbitrap instrument: full-scan high-resolution mass spectrometry, targeted single ion monitoring (t-SIM), and t-SIM followed by data-dependent tandem mass spectrometry. Overall, a similar quantitative performance was noticed for the different scan modes. The analytical method was successfully applied to measure basal phytohormone levels in six different rice accessions, comprising Oryza sativa ssp. japonica, indica, and Oryza glaberrima. Hormone concentrations were higher in shoots than in roots or at least similar. Except for a lower level of salicylic acid in shoots of O. glaberrima versus O. sativa, no other differences in hormone levels could be noticed that were dependent of the (sub)species assignment of the analyzed accessions. Making use of the benefits of full-scan high-resolution mass spectrometry, a first post-run suspect screening was performed, suggesting - based on accurate mass measurements and isotopic patterns - the possible presence of about 50 additional plant hormones in the rice tissues.ᅟ [ABSTRACT FROM AUTHOR]

In recent years, an increasing number of research papers revealed that the compositional and volumetric alterations in the extracellular matrix are the consequences of aging and may be related to Alzheimer's disease (AD). In this study, we aimed to demonstrate the alterations in hippocampal extracellular fluid proteins in vivo using the 5XFAD mouse model. Samples were obtained from hippocampi of 5XFAD mice (n = 6) and their non-transgenic littermates by intracerebral push-pull perfusion technique at 3 months of age, representing the pre-pathological stage of the AD. Proteins in the hippocampal perfusates were analyzed by Ultra Performance Liquid Chromatography-Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry (UPLC-ESI-qTOF-MS/MS). 178 proteins were identified and 19 proteins of them were found to be statistically significantly altered (p≤0.05, fold change ≥40%, unique peptide count ≥3) in the hippocampal CA1 extracellular fluid of the 5XFAD mouse model. Ingenuity pathway analysis of the protein expression results identified IL6 as an upstream regulator. The upregulation of IL6 was validated by immunohistochemical staining of the hippocampus and cortex of the 5XFAD mice prior to Aβ plaque formation. Furthermore, the iron level in the hippocampus was measured by inductively coupled plasma-mass spectrometry as IL6 is mentioned in several studies to take part in iron homeostasis and inflammation and found to be increased in 5XFAD mice hippocampus. Alterations in extracellular matrix proteins in addition to increasing amount of hippocampal IL6 and iron in the early stages of AD may reveal inflammation-mediated iron dyshomeostasis in the early stages of neurodegeneration. [ABSTRACT FROM AUTHOR]

The electrospray ionization (ESI) is a complex process and there has been a long debate regarding the gas-phase effect on ion generation in the process. In this paper we investigated the effect of liquid chromatographic mobile phase additives (formic acid, aqueous ammonia and their combination) on the ESI signal intensities for a wide variety of compounds. The addition of a trace amount of aqueous ammonia to the common formic acid–methanol mobile phase significantly enhances the ESI signals of protonated molecules and suppresses the formation of sodium adduct ions. This effect is well observed for the compounds containing the –N–C=O group but not for those without N or O atoms. The ESI signal intensity of deprotonated molecules increases with increase in pH of the mobile phase for neutral compounds, such as substituted urea, whereas this trend is not observed for acidic compounds such as phenoxy acids. The mechanistic analysis regarding liquid- and gas-phase protonation and deprotonation is discussed. [ABSTRACT FROM AUTHOR]

Guayusa tea is derived from the leaves of the Ilex guayusa Loes. plant, which is native to the Amazon rainforest. Beyond its pleasant sensory properties, Guayusa tea is rich in antioxidants, phenolics, and minerals. In this study, the effects of infusion time, temperature, and solvent conditions on the color, antioxidant capacity, total phenolic content, phenolic profile, and antimicrobial activity of Guayusa (Ilex guayusa Loes.) tea were investigated. Guayusa tea samples were prepared using two different solvents, ethanol and water, with 4, 6, and 8-h infusions at 60 and 70 °C. Liquid chromatography, diode array detection, and electrospray ionization tandem mass spectrometry (LC-DAD-ESI-MS/MS) were used to determine a comprehensive profile of phenolic compounds and to detect differences due to infusion conditions. Moreover, after the Guayusa tea infusion with the highest bioactive properties was determined, the effects of in vitro gastrointestinal digestion on the total phenolic content, antioxidant capacity, and phenolic compounds of the Guayusa tea infusion were measured. Phenolic profile analysis identified 29 compounds, among which chlorogenic acid and its derivatives were predominant. The increase in infusion time was correlated with an elevation in total phenolic content. Significant differences were observed between water and ethanol infusions of Guayusa in terms of phenolics and antioxidants. The total amount of phenolic compounds in the samples prepared with both solvents was found to increase after oral intake, depending on the digestion stage; meanwhile, the amounts of flavonoid compounds and di-O-caffeoylquinic acid derivatives decreased during digestion. [ABSTRACT FROM AUTHOR]

This paper presents the study of the occurrence of ten endocrine-disrupting compounds in twenty wastewater samples, collected from different sampling points throughout a wastewater treatment plant process. This work was assessed using ultra-performance liquid chromatography with electrospray ionization-tandem mass spectrometry that provides simultaneous quantification and confirmation of the presence of these emerging compounds. All samples were previously cleaned with vacuum filtration and extracted by solid-phase extraction. The compounds studied in this work are 17β-estradiol, ethinylestradiol, estriol, estrone, progesterone, mestranol and diethylstilbestrol, 4-n-nonylphenol, 4-tert-octylphenol and bisphenol A. The analytical limits were calculated for each compound and were used to identify and these target compounds in a wastewater treatment plant. The main conclusions obtained during this study emphasized that wastewater is an important contamination source of these compounds, the most common being bisphenol A and nonylphenol and wastewater treatment plants are not structured to remove endocrine-disrupting compounds. However some removal efficiencies were achieved for estriol (around 98 %) and bisphenol A (around 67 %) along treatment process, indicating that with some preventive approaches it is possible to minimize this problem. [ABSTRACT FROM AUTHOR]

Remdesivir (RDV), a nucleoside analogue prodrug, is used to treat viral diseases including COVID-19. The drug (RDV) was stressed under acidic, basic and neutral hydrolysis, oxidation, photolysis, and thermal conditions according to the International Council for Harmonisation (ICH) prescribed guidelines Q1A (R2). A total of nine degradation products were formed under acidic (DP1-DP5), basic (DP5-DP8) and neutral (DP5) hydrolysis, and oxidation (DP9) stress conditions, whereas the drug was found to be stable under thermal and photolytic stress conditions. The structures of the degradation products were elucidated by using a simple and rapid ultra high-performance liquid chromatography coupled to electrospray interface with quadrupole time-of-flight tandem mass spectrometer (UPLC/ESI-Q-TOF-MS/MS) method. [ABSTRACT FROM AUTHOR]

Buxus papillosa is one of the most extensively studied species of the genus Buxus known to possess steroidal alkaloids which can be used for assessing the various pharmacological activities of this plant. This paper describes the liquid chromatography–electrospray ionization triple quadrupole mass spectrometry (LC–ESI-QQQ-MS) method for the quantification of six steroidal alkaloids as chemical markers in the extracts of leaves, roots and stems of B. papillosa . Quantitative MS/MS analysis was carried out by optimization of the most sensitive transition for each analyte. This has yielded detection and quantification limits of 0.486–8.08 ng/mL and 1.473–24.268 ng/mL, respectively for all analytes. Linearity of response was also achieved and the regression coefficient found to be >0.99 for all analyzed compounds. The newly developed MRM (Multiple Reaction Monitoring) method showed excellent sensitivity for the quantification of steroidal alkaloids within 15 min run time. This paper describes the application of LC–QQQ-MS technique for steroidal alkaloids analysis in plant samples. [ABSTRACT FROM AUTHOR]

Liuwei Dihuang Wan (LDW), a classic Chinese medicinal formula, has been used to improve or restore declined functions related to aging and geriatric diseases, such as impaired mobility, vision, hearing, cognition, and memory. It has attracted increasing attention as one of the most popular and valuable herbal medicines. However, the systematic analysis of the chemical constituents of LDW is difficult and thus has not been well established. In this paper, a rapid, sensitive, and reliable ultra-performance LC with ESI quadrupole TOF high-definition MS method with automated MetaboLynx analysis in positive and negative ion mode was established to characterize the chemical constituents of LDW. The analysis was performed on a Waters UPLC™ HSS T3 using a gradient elution system. MS/MS fragmentation behavior was proposed for aiding the structural identification of the components. Under the optimized conditions, a total of 50 peaks were tentatively characterized by comparing the retention time and MS data. It is concluded that a rapid and robust platform based on ultra-performance LC with ESI quadrupole TOF high-definition MS has been successfully developed for globally identifying multiple constituents of traditional Chinese medicine prescriptions. This is the first report on the systematic analysis of the chemical constituents of LDW. [ABSTRACT FROM AUTHOR]

The present paper describes a method for the identification of intact high molecular weight glutenin subunits (HMW-GS), the quality determining proteins from the wheat storage proteome. The method includes isolation of HMW-GS from wheat flour, further separation of HMW-GS by reversed-phase high-performance liquid chromatography (RP-HPLC), and their subsequent molecular identification with electrospray ionization mass spectrometry using a quadrupole-time-of-flight mass analyzer. For HMW-GS isolation, wheat proteins were reduced and extracted from flour with 50% 1-propanol containing 1% dithiothreitol. HMW-GS were then selectively precipitated from the protein mixture by adjusting the 1-propanol concentration to 60%. The composition of the precipitated proteins was first evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with Coomassie staining and RP-HPLC with ultraviolet detection. Besides HMW-GS (≥65%), the isolated proteins mainly contained ω5-gliadins. Secondly, the isolated protein fraction was analyzed by liquid chromatography-mass spectrometry. Optimal chromatographic separation of HMW-GS from the other proteins in the isolated fraction was obtained when the mobile phase contained 0.1% trifluoroacetic acid as ion-pairing agent. Individual HMW-GS were then identified by determining their molecular masses from the high-resolution mass spectra and comparing these with theoretical masses calculated from amino acid sequences. Using formic acid instead of trifluoroacetic acid in the mobile phase increased protein peak intensities in the base peak mass chromatogram. This allowed the detection of even traces of other wheat proteins than HMW-GS in the isolated fraction, but the chromatographic separation was inferior with a major overlap between the elution ranges of HMW-GS and ω-gliadins. Overall, the described method allows a rapid assessment of wheat quality through the direct determination of the HMW-GS composition and offers a basis for further top-down proteomics of individual HMW-GS and the entire wheat glutenin fraction. [ABSTRACT FROM AUTHOR]

Copyright of Dairy Science & Technology (Springer Science & Business Media B.V.) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights • A method for the analysis of typical HMOs was validated. • Neutral and acidic HMOs are concomitantly quantified in the same analysis. • The method was applied to analyze HMOs in real human milk samples. • Accurate and reliable quantification of HMOs was achieved. • The method allows the Lewis and Secretor phenotype of the mother to be determined. Abstract Human milk oligosaccharides (HMOs) are free glycans naturally present in human milk that act as prebiotics, prevent pathogen binding, modulate the immune system and support brain development in infants. The HMOs composition and concentrations vary significantly among different women mainly because of the direct influence of the Secretor and Lewis phenotypes on HMOs biosynthesis. Analytical methods that can identify the differences in the HMOs composition and concentrations are a fundamental tool in HMOs research. This paper describes a simple HMOs extraction and analysis for the simultaneous and absolute quantification of neutral and acidic HMOs by graphitized carbon liquid chromatography–electrospray ionization–mass spectrometry. This method was validated and applied to analyze HMOs in the human milk obtained from 10 women. This method allows accurate and reliable quantification of HMOs and can be used to determine differences in HMOs concentrations throughout lactation and among women with different Secretor and Lewis phenotypes. [ABSTRACT FROM AUTHOR]

This paper reports the application of liquid chromatography electrospray ionization ion trap–orbitrap mass spectrometry for the determination of 18 mycotoxins (aflatoxins, fumonisins, trichothecenes, ochratoxin A, sterogmatocystin, beauvaricin, zearalenone and zearalenol) in beer. The extraction procedure was carried out by solid phase extraction (SPE): SPE columns were conditioned with acetonitrile/methanol and water. Beer was loaded onto the column which was washed with water. In these conditions, the recoveries were more than 65% and the relative standard deviation (RSD) were below 18%. The lowest limits of quantification (LLOQ) ranged from 9 to 155 ng ml−1. Matrix-matched calibration was performed for each beer and reliable results were obtained from selected mycotoxins. The method was applied to the analysis of 25 commercial beers. Taking advantage of the hybrid capabilities, the presence of other mycotoxins were checked; enniatins (A, A1, B and B1) and fusaproliferin were studied in all the tested samples. The survey detected the presence of zearalenone in one stout beer sample. [ABSTRACT FROM AUTHOR]

In this paper, a simple and cheap method for the simultaneous preconcentration and sensitive determination of three hexabromocyclododecane (HBCD) diastereomers (α-, β-, and γ-HBCD) in environmental water samples has been developed. It was based on solid phase extraction (SPE) and rapid resolution liquid chromatography-electrospray tandem mass spectrometry. Bamboo charcoal, one kind of cheap material, was investigated and used as SPE adsorbent for the enrichment and determination of HBCD diastereomers. Related important parameters affecting extraction efficiencies, including type and volume of eluant, amount of sorbent, sample pH, flow rate, and sample volume, were investigated and optimized in detail. Under the optimum conditions, experimental data exhibited excellent linear relationships between peak area and concentrations over the range 0.1-10 μg L. The limits of detection and precision were in the range of 0.005-0.015 μg L and 4.59-7.47%, respectively. The proposed method has been successfully applied for the trace analysis of HBCD diastereomers in real-world environmental water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This paper presented the applications of liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) and ultra-high-pressure liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC QqTOF MS) for the determination of 148 pesticides in fruits and vegetables. Pesticides were extracted from fruits and vegetables using a buffered QuEChERS method. Quantification was achieved using matrix-matched standard calibration curves with isotopically labeled standards or a chemical analog as internal standards in an analytical range from 5 to 500 μg/kg. The method performance parameters including overall recovery, intermediate precision, and measurement uncertainty were evaluated according to a statistically designed experiment, i.e., a nested design. For LC/ESI-MS/MS, 95% of the pesticides had recoveries between 81% and 110%; 97% had an intermediate precision ≤20%; and 95% (in fruits) or 93% (in vegetables) showed measurement uncertainty ≤40%. Compared to LC/ESI-MS/MS, UHPLC QqTOF MS showed a relatively poor repeatability and large measurement uncertainty. About 93% (in fruits) or 94% (in vegetables) of the pesticides had recoveries between 81% and 110%; 86% (in fruits) or 90% (in vegetables) had an intermediate precision ≤20%; and 79% (in fruits) or 88% (in vegetables) showed measurement uncertainty ≤40%. LC/ESI-MS/MS proved to be the first choice for quantification or pre-target analysis due to its superior sensitivity and good repeatability. UHPLC QqTOF MS provided accurate mass measurement and isotopic patterns, and was an ideal tool for post-target screening and confirmation. [ABSTRACT FROM AUTHOR]

Adulteration of botanical dietary supplements with prohibited synthetic drugs has become a serious problem. In this paper, a method for testing synthetic drugs used to adulterate botanical dietary supplements was developed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) coupled with a linearity ion-trap system in the multiple reaction monitoring (MRM) plus enhanced product ion (EPI) mode. Twenty-three drugs exhibiting various pharmacological effects, comprising blood pressure and lipid-lowering agents, sedative drugs, anti-diabetic drugs, weight-reducing agents and aphrodisiac compounds, were studied. For all drugs, a single transition was monitored using protonated molecules as precursor ions. EPI spectra were stored in a library and recognized by library searching. Several undeclared drugs were identified in herbal remedies, e.g., glibenclamide, sibutramine hydrochloride and sildenafil. Overall, 35 positive samples were found out of a total of 105 botanical dietary supplements tested. The method was selective, sensitive, rapid, high-throughput and reliable. [ABSTRACT FROM AUTHOR]

This paper describes a rapid, simple, sensitive, specific, and accurate analytical method for the determination of clarithromycin and 14-hydroxy clarithromycin (metabolite) in human plasma by high performance liquid chromatography with electrospray ionization tandem mass spectrometric detection (LC-MS/MS), using erythromycin as an internal standard (IS). The drug, metabolite, and internal standard were extracted by a precipitation method with the use of acetonitrile as a precipitant and separated on a C18 analytical column (5 µ, 4.6 × 100 mm). The mobile phase consisted of acetonitrile: 10 mM ammonium formate buffer (90:10 v/v). Detection was carried out by positive electro spray ionization (ESI+) in multiple reaction monitoring (MRM) mode. The chromatographic separations were obtained within 2.0 min and were linear in the concentration range of 36.5-5066.2 ng/mL for clarithromycin and 28.3-3934.1 ng/mL for 14-hydroxy clarithromycin. The limit of quantification for clarithromycin and 14-hydroxy clarithromycin were 36.5 and 28.3 ng/mL. The average recoveries for clarithromycin, 14-hydroxy clarithromycin, and the IS were 85.6%, 88.8%, and 85.0%, respectively. The results showed that the proposed method is rapid, sensitive, and reproducible to the quantitative determination of clarithromycin and 14-hydroxy clarithromycin in human plasma. Moreover, the proposed method was successfully applied for the bioequivalence study of clarithromycin. [ABSTRACT FROM AUTHOR]

The weakest step in the analytical procedure for speciation analysis is extraction from a biological material into an aqueous solution which undergoes HPLC separation and then simultaneous online detection by elemental and molecular mass spectrometry (ICP–MS/ES-MS). This paper describes a study to determine the speciation of arsenic and, in particular, the arsenite phytochelatin complexes in the root from an ornamental garden plant Thunbergia alata exposed to 1 mg As L−1 as arsenate. The approach of formic acid extraction followed by HPLC–ES-MS/ICP–MS identified different AsIII–PC complexes in the extract of this plant and made their quantification via sulfur ( m/ z 32) and arsenic ( m/ z 75) possible. Although sulfur sensitivity could be significantly increased when xenon was used as collision gas in ICP–qMS, or when HR-ICP–MS was used in medium resolution, the As:S ratio gave misleading results in the identification of AsIII–PC complexes due to the relatively low resolution of the chromatography system in relation to the variety of As–peptides in plants. Hence only the parallel use of ES-MS/ICP–MS was able to prove the occurrence of such arsenite phytochelatin complexes. Between 55 and 64% of the arsenic was bound to the sulfur of peptides mainly as AsIII(PC2)2, AsIII(PC3) and AsIII(PC4). XANES (X-ray absorption near-edge spectroscopy) measurement, using the freshly exposed plant root directly, confirmed that most of the arsenic is trivalent and binds to S of peptides (53% As–S) while 38% occurred as arsenite and only 9% unchanged as arsenate. EXAFS data confirmed that As–S and As–O bonds occur in the plants. This study confirms, for the first time, that As–peptides can be extracted by formic acid and chromatographically separated on a reversed-phase column without significant decomposition or de-novo synthesis during the extraction step. [ABSTRACT FROM AUTHOR]

This paper describes a liquid chromatographic/tandem mass spectrometric (LC/MS–MS) method specifically designed for the screening of synthetic glucocorticosteroids in human urine. The method is designed to recognize a common mass spectral fragment formed from the particular portion of the molecular structure that is common to all synthetic glucocorticosteroids and that is fundamental to their pharmacological activity. As such, the method is also suitable for detecting unknown substances, provided they contain the portion of the molecular structure selected as the analytical target. The effectiveness of this approach was evaluated on seventeen synthetic glucocorticosteroids. Urine samples, including blank urines spiked with one or more synthetic glucocorticosteroids, were treated according to a standard procedure (enzymatic hydrolysis, liquid/liquid extraction and evaporation to dryness) and analyzed using LC/MS-MS with electrospray ionization (ESI). MS–MS acquisition was carried out in a precursor ion scan, and the results were compared with those obtained by a previously developed reference technique based on acquisition in the multiple reaction monitoring (MRM) mode. All of the glucocorticosteroids considered in this study are clearly detectable in urine, with a limit of detection in the concentration range 5–20 ng/mL, depending on the glucocorticosteroid structure. The proposed method is therefore suitable for the detection of glucocorticosteroids in urine samples taken for “in competition” sport anti-doping control tests, matching the requirements of the World Anti-Doping Agency (WADA) for accredited anti-doping laboratories. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This paper describes the extension of a previously published method based on liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) from 39 to currently 87 analytes. Besides the mycotoxins for which regulated concentrations exist, the method now comprises not only almost all mycotoxins for which standards are commercially available, but also a number of other important metabolites produced by fungi involved in food spoilage. The method is based on a single extraction step using an acidified acetonitrile/water mixture followed by analysis of the diluted crude extract. Method performance characteristics were determined after spiking breadcrumbs as model matrix at multiple concentration levels. With very few exceptions, coefficients of variation of the whole procedure of <5% and repeatabilities at the highest spiking level of <7% were obtained. Limits of detection ranged between 0.02 and 225 μg kg−1. The quantitative determination of ergopeptides was disturbed by epimerization due to the acidic conditions. From the remaining 77 analytes, the apparent recoveries of nine substances deviated significantly from the CEN target range of 70–110% due to incomplete extraction and/or matrix effects. In principle, the latter can be compensated for by the application of matrix-matched calibration. The developed method was applied to 18 moldy samples (including bread, fruits, vegetables, jam, cheese, chestnuts and red wine) from private households. This study revealed the great value of the described method: 37 different fungal metabolites were identified at concentrations of up to 33 mg kg−1, and some of these have never been reported before in the context of moldy food products. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The aim of this paper was to develop a specific and sensitive liquid chromatography/electrospray ionization mass spectrometry method for the determination of imatinib and its metabolite in human plasma. The method involved a solid phase extraction of the compounds and internal standard (imatinib‐D8) from human plasma. LC separation was performed on a SymmetryShield™ RP8 column with a mobile phase of water:acetonitrile:formic acid. MS data were acquired in single ion monitoring mode at m/z 494.4, m/z 480.4 and m/z 502.4 for imatinib, N‐desmethyl‐imatinib, and imatinib‐D8, respectively. The absence of ion suppression was demonstrated. The drug/internal standard peak area ratios were linked via a quadratic relationship to plasma concentrations (8.35–8350 µg/L for imatinib and N‐desmethyl‐imatinib). Precision was 2.8–10.8% and accuracy was 91.3–111.3%. Extraction recoveries were &nvge;70%. The lower limit of quantitation was 8.35 µg/L for both imatinib and N‐desmethyl‐imatinib. [ABSTRACT FROM AUTHOR]

Drinking water is a complex mixture that contains thou- sands of naturally occurring and anthropogenic contaminants. Liquid chromatography-mass spectrometry (LC- MS) methods have gained a tremendous popularity in monitoring nonvolatile, highly polar, and thermally labile components in drinking water. It is well recognized, however, that there are difficulties or limitations of LC- MS methods associated with (1) significant resources (time and effort) involved in sample preparation (preconcentration, fractionation, separation), (2) low screening capacity for target contaminants, and (3) insufficient capabilities for structural identification (elucidation) of nontarget contaminants. Consequently, LC-MS methods are mainly used for the detection of target contaminants (compounds identified in drinking water before), seldom for the structural identification of abundant nontarget pollutants (unidentified pollutants in drinking water), and almost never for the structural identification of nontarget components at a trace level. The paper presents a new method of electrospray ionization high field asymmetric waveform ion mobility spectrometry mass spectrometry (ESI-FAIMS-MS), which can detect a large number of water pollutants in a quick and convenient fashion without preconcentration, fractionation, derivatization, or column separation. Most importantly, the method provides structural identification of nontarget contaminants including species present in drinking water at a sub-parts-per-billion concentration level. The identification of previously unknown contaminants was based on mass measurements of investigated ions and their fragments in mass and tandem mass spectrometry. Elemental compositions of these ions, determined by mass measurements, were used to link dissociation patterns of investigated species with their chemical structures. Characterization of non-target contaminants of chlorine-treated drinking water by ESI-FAIMS-MS has revealed many previously unknown disinfection byproducts. The most intriguing compound, from a group of highly polar hydroxycarboxylic acids discovered in the study, was the most abundant component of drinking water, glycolic acid. Glycolic acid (toxic to kidneys and associated with a moderate maternal toxicity) has never been considered as a drinking water contaminant, despite the fact that it is present in drinking water at a higher concentration (high ppm) than concentrations of highly polar water pollutants that had attracted most attention in the past. The process of structural elucidation of discovered pollutants, including ultratrace contaminants representing a variety of carboxylic acids, will be presented in detail. The structural identification of highly polar contaminants in drinking water presented in the paper is rarely reported in the literature. The key experimental feature of the ESI-FAIMS-MS method is FAIMS separation, which significantly improves the identification capabilities of mass spectrometry. [ABSTRACT FROM AUTHOR]

This paper reports the development of a fully automated method for the multianalyte determination of twenty pesticides belonging to different classes (triazines, phenylureas, organophosphates, anilines, acidic, propanil, and molinate) in natural and treated waters. The method, based on on-line solid-phase extraction–liquid chromatography–electrospray–tandem mass spectrometry, is highly sensitive (limits of detection between 0.004 and 2.8 ng L−1), precise (relative standard deviations between 2.0 and 12.1%), reliable (two selected reaction-monitoring transitions are monitored per compound), rapid (45 min per sample), and simple. The application of this method to the monitoring of the target compounds in a waterworks revealed the presence of the pesticides investigated at concentrations up to 516 and 82 ng L−1 (total pesticide concentration) in river water and ground water, respectively, used as sources, and their gradual removal through the purification process. [ABSTRACT FROM AUTHOR]

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a versatile coupling system which combines both selectivity and sensitivity and certainty. Hence, it is generally considered as the most reliable technique to quantify chemical compounds in complex matrices. In the present paper, we evaluate the performance of LC-MS/MS methods for the quantification of 3-nitrotyrosine in human urine in order to point out its dependence on the design of the quantification method, and emphasize the role of matrix effects in the performance. We compare external and internal calibrations, isotope dilution and isotopomer-based exact matching. The role of both sample preparation and multiple transitions monitoring is particularly addressed. [ABSTRACT FROM AUTHOR]

Data-independent acquisition (DIA) mode in liquid chromatography (LC) high-resolution mass spectrometry (HRMS) has emerged as a powerful strategy in untargeted metabolomics for detecting a broad range of metabolites. However, the use of this approach also represents a challenge in the analysis of the large datasets generated. The regions of interest (ROI) multivariate curve resolution (MCR) approach can help in the identification and characterization of unknown metabolites in their mixtures by linking their MS1 and MS2 DIA spectral signals. In this study, it is proposed for the first time the analysis of MS1 and MS2 DIA signals in positive and negative electrospray ionization modes simultaneously to increase the coverage of possible metabolites present in biological systems. In this work, this approach has been tested for the detection and identification of the amino acids present in a standard mixture solution and in fish embryo samples. The ROIMCR analysis allowed for the identification of all amino acids present in the analyzed mixtures in both positive and negative modes. The methodology allowed for the direct linking and correspondence between the MS signals in their different acquisition modes. Overall, this approach confirmed the advantages and possibilities of performing the proposed ROIMCR simultaneous analysis of mass spectrometry signals in their differing acquisition modes in untargeted metabolomics studies. [ABSTRACT FROM AUTHOR]

Due to the clinical significance of steroidal saponins, multiple stems Paris polyphylla var. yunnanensis (MPPY) has attracted much interest and played a crucial role in drug development. However, developing a simple and efficient method to analyze the chemical composition of MPPY remains a pronounced challenge. Herein, we report for the first time the component analysis of MPPY rhizomes using the chromatographic fingerprint combined with ultra-high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS) method. Nineteen compositions of MPPY were qualitatively investigated by such strategy and confirmed as steroidal saponins. Among these compositions, 17 steroidal saponins were detected in 10 different batches of MPPY. Thirteen common peaks appeared in chromatographic fingerprint, of which 11 common peaks can be attributed by LC--MS data. The experimental facts demonstrate that the method established is simple, rapid, and reliable to evaluate the quality of MPPY. Besides, the correlation and difference of steroidal saponins in the rhizomes of MPPY from different places were also studied. [ABSTRACT FROM AUTHOR]

Chlortetracycline is (CTC) is a tetracycline antibiotic which is being in the white-tailed deer industry to improve production and animal health. In this paper, we present a method for determining chlortetracycline residues in edible white-tailed deer tissues, using liquid chromatography with heated electrospray ionization and mass spectrometry detection. The procedure involved extraction with EDTA-McIlvaine buffer at pH 4.0, followed by solid-phase extraction cleanup using a hydrophilic-lipophilic balance (HLB) cartridge. The liquid chromatography analysis was performed with heated electrospray ionization and mass spectrometry detection. The limit of quantification for the method was 2.7 ng/g and limit of detection was 0.8 ng/g. The recovery values were >78.5% for muscle, 65.1% for kidney, 63.1% for liver. Mean tissue residue concentration of chlortetracycline and it's epimer, 4-epi chlortetracycline (4-epi-CTC) at 10-day withdrawal period for kidney, liver, muscle was 122.8, 44.7 and 26.7 ng/g, respectively. Chlortetracycline tissue residue concentration at 45-day withdrawal period for kidney, liver, muscle was 19.2, 28.9 and 10.7 ng/g, respectively. Mean tissue concentration of CTC was less than the established maximum residual limit (MRL) values for bovine tissues. We have validated and successfully applied this method in the qualitative and quantification of chlortetracycline in white-tailed deer tissue samples. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present the development and validation of a high-resolution full scan (HR-FS) electrospray ionization (ESI) liquid chromatography coupled to quadrupole Orbitrap mass spectrometer (LC/Q/Orbitrap MS) platform for the screening of prohibited substances in human urine according to World Antidoping Agency (WADA) requirements. The method was also validated for quantitative analysis of six endogenous steroids (epitestosterone, testosterone, 5α-dihydrotestosterone, dehydroepiandrosterone, androsterone and etiocholanolone) in their intact sulfates form. The sample preparation comprised a combination of a hydrolyzed urine liquid–liquid extraction and the dilute & shoot addition of original urine in the extracted aliquot. The HR-FS MS acquisition mode with Polarity Switching was applied in combination of the Quadrupole-Orbitrap mass filter. The HR-FS acquisition of analytical signal, for known and unknown small molecules, allows the inclusion of all analytes detectable with LC–MS for antidoping investigations to identify the use of known or novel prohibited substances and metabolites after electronic data files’ reprocessing. The method has been validated to be fit-for-purpose for the antidoping analysis. [ABSTRACT FROM AUTHOR]

This paper described a reliable and simple method for the selective determination of MQCA in animal tissues using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A highly targeted immunoaffinity column was used for sample purification after enzymatic hydrolysis. The purified extracts were analyzed by reversed-phase HPLC–MS/MS in positive ESI and multiple reaction monitoring mode. The calibration curves showed good linearity with correlation coefficient (r 2 ) larger than 0.995. The average recoveries at the spiked levels of 0.5, 2.0 and 20 μg kg − 1 were 90.2% to 103.5% with intra-day and inter-day relatives standard deviations (RSD, n = 6) ranging from 1.8% to 6.7% and 3.5% to 7.6% respectively. The limit of quantification (LOQ) was 0.5 μg kg − 1 , which can fulfil the maximum residue level (MRL) of 4.0 μg kg − 1 stipulated by the Agricultural Minister of China and the requirement of the confirmatory criteria according to the European Commission Decision 2002/657/EC. The method is sensitive, accurate, convenient and rapid, and has been successfully applied in real samples. [ABSTRACT FROM AUTHOR]

The degradation kinetics, pathways and disinfection by-products (DBPs) formation of iopamidol by chlorine and chloramines were investigated in this paper. The chlorination kinetics can be well described by a second-order model. The apparent second-order rate constants of iopamidol chlorination significantly increased with solution pH. The rate constants of iopamidol with HOCl and OCl − were calculated as (1.66 ± 0.09) × 10 −3 M −1 s −1 and (0.45± 0.02) M −1 s −1 , respectively. However, the chloramination of iopamidol fitted well with third-order kinetics and the maximum of the apparent rate constant occurred at pH 7. It was inferred that the free chlorine (i.e., HOCl and OCl − ) can react with iopamidol while the combined chlorine species (i.e., NH 2 Cl and NHCl 2 ) were not reactive with iopamidol. The main intermediates during chlorination or chloramination of iopamidol were identified using ultra performance liquid chromatography - electrospray ionization-mass spectrometry (UPLC-ESI-MS), and the destruction pathways including stepwise deiodination, hydroxylation as well as chlorination were then proposed. The regular and iodinated DBPs formed during chlorination and chloramination of iopamidol were measured. It was found that iodine conversion from iopamidol to toxic iodinated DBPs distinctly increased during chloramination. The results also indicated that although chloramines were much less reactive than chlorine toward iopamidol, they led to the formation of much more toxic iodinated DBPs, especially CHI 3 . [ABSTRACT FROM AUTHOR]

Dalbergia odorifera, a traditional Chinese medicine, has been used to treat cardio- and cerebrovascular diseases in China for thousands of years. Flavonoids are major active compounds in D. odorifera. In this paper, a rapid and sensitive ultra-high performance liquid chromatography-triple quadrupole mass spectrometry method was developed and validated for simultaneous determination of 17 flavonoids in D. odorifera. Quantification was performed by multiple reaction monitoring using electrospray ionization in negative ion mode. Under the optimum conditions, calibration curves for the 17 analytes displayed good linearity (r2 > 0.9980). The intra- and inter-day precisions (relative standard deviations) were lower than 5.0%. The limit of quantitation ranged from 0.256 to 18.840 ng/mL. The mean recovery range at three spiked concentrations was 94.18–101.97%. The validated approach was successfully applied to 18 samples of D. odorifera. Large variation was observed for the contents of the 17 analytes. Sativanone and 3′-O-methylviolanone were the dominant compounds. The fragmentation behaviors of six flavonoids were investigated using UPLC with quadrupole time-of-flight tandem mass spectrometry. In negative ion electrospray ionization mass spectrometry, all the flavonoids yielded prominent [M − H]− ions. Fragments for losses of CH3, CO, and CO2 were observed in the mass spectra. Formononetin, liquiritigenin, isoliquiritigenin, sativanone, and alpinetin underwent retro-Diels–Alder fragmentations. The proposed method will be helpful for quality control of D. odorifera. [ABSTRACT FROM AUTHOR]

Tetrodotoxin (TTX) is a kind of low-molecular-weight non-protein neurotoxin. It is one of the most potent neurotoxins found in nature, and it is found in puffer fish and various marine biota. The low sensitivity of previous analytical methods limited their application in puffer fish organ samples. This study established a method for the accurate and fast determination of TTX by reversed ultra-performance liquid chromatography coupled with proton-enhanced electron spray ionization–tandem mass spectrometry. The method yields good peak shapes, high sensitivity and low coeluted interferences. The method was successfully applied to determine TTX in puffer fish tissue samples of about 0.2 g. [ABSTRACT FROM AUTHOR]

The aerosol constituents generated from JUUL Menthol pods with 3.0% and 5.0% nicotine by weight (Me3 and Me5) are characterized by a non-targeted approach, which was developed to detect aerosol constituents that are not known to be present beforehand or that may be measured with targeted methods. Three replicates from three production batches (n = 9) were aerosolized using two puffing regimens (intense and non-intense). Each of the 18 samples were analyzed by gas chromatography electron ionization mass spectrometry and by liquid chromatography electrospray ionization high-resolving power mass spectrometry. All chemical constituents determined to differ from control were identified and semi-quantified. To have a complete understanding of the aerosol constituents and chemistry, each chemical constituent was categorized into one of five groups: (1) flavorants, (2) harmful and potentially harmful constituents, (3) leachables, (4) reaction products, and (5) chemical constituents that were unable to be identified or rationalized (e.g., chemical constituents that could not be categorized in groups (1–4). Under intense puffing, 74 chemical constituents were identified in Me3 aerosols and 68 under non-intense puffing, with 53 chemical constituents common between both regimens. Eighty-three chemical constituents were identified in Me5 aerosol using an intense puffing regimen and seventy-five with a non-intense puffing regimen, with sixty-two chemical constituents in common. Excluding primary constituents, reaction products accounted for the greatest number of chemical constituents (approximately 60% in all cases, ranging from about 0.05% to 0.1% by mass), and flavorants—excluding menthol—comprised the second largest number of chemical constituents (approximately 25%, ranging consistently around 0.01% by mass). The chemical constituents detected in JUUL aerosols were then compared to known constituents from cigarette smoke to determine the relative chemical complexities and commonalities/differences between the two. This revealed (1) a substantial decrease in the chemical complexity of JUUL aerosols vs. cigarette smoke and (2) that there are between 55 (Me3) and 61 (Me5) unique chemical constituents in JUUL aerosols not reported in cigarette smoke. Understanding the chemical complexity of JUUL aerosols is important because the health effects of combustible cigarette smoke are related to the combined effect of these chemical constituents through multiple mechanisms, not just the effects of any single smoke constituent. [ABSTRACT FROM AUTHOR]

Among the different Hawthorn species, Crataegus monogyna seems to be one of the most often used in herbal medicine, and is commercially available. The methanolic extract and the acidified methanol extract of an herbal medicinal product based on Crataegus monogyna inflorescences were analyzed by using high-pressure liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS). On the basis of m/z of [M-H]− ions and characteristic fragmentation patterns, a number of polyphenolic compounds, namely flavonoids and chlorogenic acids, were identified. It was found that the contents of the acid extract were enriched with methyl chlorogenates showing attractive biochemical properties. Analogous results were obtained for other plant materials, e.g., nectarine kernels. Apart from that, acid extraction had a minor influence on the polyphenolic compounds present in the plants, and thus it did not affect the natural antioxidant values of the plant extracts. [ABSTRACT FROM AUTHOR]

Rationale: Annona species are of interest for the isolation of bioactive molecules; however, studies of Annona jahnii Saff. are limited. The exploration of bioactive metabolites of endophytes isolated from this species is unprecedented and allows the preservation of the host plant, in addition to enabling the discovery of compounds with promising biological activities. Methods: Ethyl acetate extracts from the cultured media of five fungi were obtained. The antioxidant capacity of the extracts was measured using the 1,1‐diphenyl‐2‐picrylhydrazyl free radical method. Antimicrobial activity was determined using the microdilution method in broth in 96‐well plates. The exploration of the metabolic profile of the extracts and dereplication of the compounds were performed using ultra‐high‐performance liquid chromatography/electrospray ionization/tandem mass spectrometry (UHPLC/ESI‐MS/MS) combined with analysis using molecular networking (MN). Results: A total of 1818 MS features were detected in the five selected extracts, of which 39 compounds were putatively identified. The secondary metabolites with the highest abundance were alkaloids, naphthopyrons, and cytochalasins. Other secondary metabolites include fumonisins, coumarin, and a meroterpenoid. Most of these compounds are related to specific biological properties such as antioxidant, anti‐inflammatory, antimicrobial, antiviral, and antitumor activities. Extracts F398 and F403 showed inhibitory activity of the four pathogens tested. Extracts F475 and F506 did not inhibit the growth of Staphylococcus aureus, and F407 did not inhibit the growth of Escherichia coli in addition to having potent antioxidant activity, with IC50 values of 10 μg/mL or less. Conclusions: The use of UHPLC/ESI‐MS/MS data combined with MN proved useful in the dereplication of bioactive molecules of complex extracts that are still unexplored. These initial investigations should significantly assist in further research and increase the efficiency and speed in the discovery of new sources of secondary metabolites and new natural products. [ABSTRACT FROM AUTHOR]

Different parts of Cynara scolymus L. and their green synthesized eco-friendly silver nanoparticles (AgNPs) were screened for their cytotoxicity and apoptotic activity. Results showed that flower extract AgNPs exhibited more potent cytotoxicity compared to the normal form against PC-3 and A549 cell lines with IC50 values of 2.47 μg/mL and 1.35 μg/mL, respectively. The results were compared to doxorubicin (IC50 = 5.13 and 6.19 μg/mL, respectively). For apoptosis-induction, AgNPs prepared from the flower extract induced cell death by apoptosis by 41.34-fold change and induced necrotic cell death by 10.2-fold. Additionally, they induced total prostate apoptotic cell death by a 16.18-fold change, and it slightly induced necrotic cell death by 2.7-fold. Hence, green synthesized flower extract AgNPs exhibited cytotoxicity in A549 and PC-3 through apoptosis-induction in both cells. Consequently, synthesized AgNPs were further tested for apoptosis and increased gene and protein expression of pro-apoptotic markers while decreasing expression of anti-apoptotic genes. As a result, this formula may serve as a promising source for anti-cancer candidates. Finally, liquid chromatography combined with electrospray mass spectrometry (LC-ESI-MS) analysis was assessed to identify the common bioactive metabolites in crude extracts of stem, flower, and bract. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge ionization has gained attention in the last few years due to its versatility and the vast array of molecules that can be ionized. In this study, we report on the assessment of liquid chromatography coupled to dielectric barrier discharge ionization with mass spectrometry for neutral lipid analysis. A set of different neutral lipid subclasses (triacylglycerides, diacylglycerides, and sterols) were selected for the study. The main species detected from our ionization source were [M‐H2O+H]+, [M+H]+ or [M‐R‐H2O+H]+, attributed to sterol dehydration, protonation or the fragmentation of an acyl chain accompanied by a water loss of the glycerolipids, respectively. In terms of sensitivity, the dielectric barrier discharge displayed overall improved abundances and comparable or better limits of quantitation than atmospheric pressure chemical ionization for both acylglycerols and sterols. As a case study, different archaeological samples with variable content in neutral lipids, particularly triacylglycerides, were studied. The identification was carried out by combining accurate mass and the tentative formula associated with the exact mass, retention time matching with standards, and additional structural information from in‐source fragmentation. The high degree of unsaturation and the presence of sterols revealed the potential vegetal origin of the material stored in the analyzed samples. [ABSTRACT FROM AUTHOR]

Bedaquiline (BDQ) is a new drug approved by United States Food and Drug Administration (USFDA) in 2012 for the treatment of drug-resistant tuberculosis, which has become a major threat globally. The manuscript presents the development of three liquid chromatography (LC) based analytical methods. The first is a stability indicating RP-HPLC (reverse phase-high performance liquid chromatography) method to analyze the BDQ in presence of its degradation products. Another UPLC/ESI–MS (ultra-performance liquid chromatography/electron spray ionization–mass spectrometry) method was developed for the identification of different degradation based and process related impurities and the third, preparative HPLC method was developed for the isolation of major degradation products. Eleven degradation products and one process related impurity were identified using UPLC/ESI–MS whereas preparative HPLC was used to isolate two degradation products and their chemical structure was elucidated using nuclear magnetic resonance, mass and infra-red spectral data. [ABSTRACT FROM AUTHOR]

Purpose: Currently, mass spectrometry has become an effective method for the qualitative analysis of plant-derived samples. Precursor and product ions can be obtained by tandem mass spectrometry, supplying rich information for determining the structural formulas of compounds. In this work, we review the optimization of qualitative methods using liquid chromatography-electrospray ionization-quadrupoletime of flight (LC-ESI-Q-TOF), coupled with ultraviolet and infrared spectroscopy, nuclear magnetic resonance, and mass spectrometry. This paper provides a systemic reference for researchers engaged in the qualitative analysis of plant-derived samples using LC-ESI-Q-TOF. [ABSTRACT FROM AUTHOR]

A current focus of our research is dedicated to investigating tools that can be used to couple pancreas‐on‐a‐chip systems on‐line with mass spectrometry. To enable on‐line‐cleavage of insulin´s disulfide bonds, we coupled an inter‐chain cleavage reactor with a nano liquid chromatography‐mass spectrometry system. The reactor featured a high intensity 254 nm photochemical mercury quartz lamp radiating upon an ultraviolet transparent tubing where acetone and isopropanol form hydroxyalkyl radicals which cleave insulin disulfide bridges. The cleavage allowed for robust fragmentation mass spectra of insulin using nanospray/Q‐Exactive mass spectrometry. A nano liquid chromatography separation column was placed downstream to the reactor. We found that for the nano liquid chromatography format, a silica monolith provided substantially less carry‐over and improved chromatographic performance to the investigated particle‐packed columns. The photochemical reactor/silica monolithic nano liquid chromatography/nanospray/Q‐Exactive mass spectrometry was compatible with cell culture medium, and will be further investigated for on‐line coupling with pancreas‐on‐a‐chip systems. [ABSTRACT FROM AUTHOR]

Electrospray ionization (ESI) tandem mass spectrometry coupled with liquid chromatography is a routine technique for identifying and quantifying compounds in complex mixtures. The identification step can be aided by matching acquired tandem mass spectra (MS2) against reference library spectra as is routine for electron ionization (El) spectra from gas chromatography/mass spectrometry (GC/MS). However, unlike the latter spectra, ESI MS2 spectra are likely to originate from various precursor ions for a given target molecule and may be acquired at varying energies and resolutions and have characteristic noise signatures, requiring processing methods very different from El to obtain complete and high quality reference spectra for individual analytes. This paper presents procedures developed for creating a tandem mass spectral library that addresses these factors. Library building begins by acquiring MS2 spectra for all major MS1 peaks in an infusion run, followed by assigning MS2 spectra to clusters and creating a consensus spectrum for each. Intensity-based constraints for cluster membership were developed, as well as peak testing to recognize and eliminate suspect peaks and reduce noise. Consensus spectra were then examined by a human evaluator using a number of criteria, including a fraction of annotated peaks and consistency of spectra for a given ion at different energies. These methods have been developed and used to build a library from >9000 compounds, yielding 230,000 spectra. [ABSTRACT FROM AUTHOR]

Lignin is an aromatic biopolymer that may yield valuable chemicals currently obtained solely from petroleum. However, extraction of lignin by using traditional methods, such as organosolv extraction, produces very complex mixtures. Molecular level characterization of the major components is essential to be able to rationally tailor methodology for the conversion of these mixtures to transportation fuel and valuable chemicals. In this study, high performance liquid chromatography/high resolution tandem mass spectrometry (HPLC/MSn) was used to obtain molecular weight, elemental composition and structural information for the major components in an organosolv lignin sample. HPLC/MSn coupled with hydroxide- doped electrospray ionization was used to identify the structures of the major components by using a Thermo Scientific linear quadrupole ion trap-Fourier transform ion cyclotron resonance hybrid mass spectrometer (LQIT/FT-ICR). The results reported here demonstrate that the major products of organosolv extraction are low molecular weight compounds, including monomeric and dimeric lignin units, with various functionalities. [ABSTRACT FROM AUTHOR]

Highlights: [•] The first time LC–DAD/MS n investigation on S. guangxiense led to the identification of 50 compounds. [•] Cyanogenic glycosides, triterpenoids, phenolic sulfates and organic acids are the main constituents. [ • ] This paper is valuable for understanding the chemical profiles and taxonomic position of S. guangxiense. [ABSTRACT FROM AUTHOR]