Chromatography Electrospray Ionization Mass Spectrometry Research Articles

LC-ESI-MS and GC-MS Profiling, Chemical Composition, and Cytotoxic Activity of Endophytic Fungus Pleosporales sp. Derived from Artemisia annua

The chemical profiling of ethyl acetate extract of the endophytic fungus Pleosporales sp. using liquid chromatography–electrospray ionization–mass spectrometry (LC-ESI-MS) revealed the presence of 12 metabolites of different chemical classes such as steroids, α-pyrones, asterric acid derivatives, and quinones. Additionally, the gas chromatography–mass spectrometry (GC-MS) profiling of the ethyl acetate (EtOAc) and methanol extracts exhibited the presence of fatty acids and their esters, in which methyl palmitate (18.72%, and 25.48%, respectively) and methyl linoleate (11.92% and 23.39%, respectively) were found in both extracts. On the other hand, palmitic acid (12.60%), methyl oleate (26.90%), oleic acid (4.01%) and linoleic acid (3.25%) were present only in methanol extract. Furthermore, ethyl palmitate (12.60%), 13-octadecenoic acid (19.36%), and ethyl linoleate (3.25%) occurred in EtOAc extract. A phytochemical investigation of both extracts led to the isolation of fatty acids such as palmitic acid (18), oleic acid (20), and linoleic acid (21) and their esters including methyl palmitate (13), methyl stearate (22), methyl linoleate (16), methyl 3-hydroxy-5-methylhexanoate (23), and monomethyl azelate (27), in addition to monoacyl derivatives of glycerol such as 3,3-dihydroxypropyl hexadecanoate (24), 2,3-dihydroxypropyl elaidate (25), and 1-linoleoyl-sn-glycerol (26). The structures of the isolated compounds were identified by different spectroscopic analyses including 1H- and 13C-NMR and GC-MS. The EtOAc extract exhibited a cytotoxic effect against MCF-7 and HepG-2 cell lines, with IC50 values of 4.12 ± 0.10 and 10.05 ± 0.05 μg/mL, respectively.

Lipid Marker ESI-MS Method for Quantification of Adulteration in Almond-Based Vegetable Beverage

ABSTRACT Almond-based beverages are valued for their functionalities. However, cases of adulteration are found in the literature aiming to reduce costs. In this study, almond (LA) and peanut (LP)-based beverages were used as investigational controls in commercial products analyzed by gas chromatography and direct infusion electrospray ionization mass spectrometry (ESI-MS) combined with principal component analysis (PCA). Thus, characteristic fatty acids were identified in plant-based beverages. The ESI-MS method combined with PCA indicated individualities regarding the disposition of triacylglycerol (TAG) composition, as higher intensities of TAG were found as a lipid marker at m/z 919 [TAG+NH4]+ of ions formed by arachidic (20:0), 8/heptadecenoic (17:1n-9) and oleic (18:1n-9) fatty acids in LP. The technique demonstrated efficiency in the detection of fraud due to its sensitivity, identifying peanut content in three almond-based commercial beverages (4.4–11.58%). This study highlights the importance of robust analytical methods to the authenticity and quality of food products.

Spatial distribution of differential metabolites in different parts of Tetrastigma hemsleyanum Diels et Gilg by ultrahigh-performance liquid chromatography/mass spectrometry and desorption electrospray ionization mass spectrometry imaging

Tetrastigma hemsleyanum Diels et Gilg (T. hemsleyanum) is a homology medicine and food that is rich in bioactive ingredients such as flavonoids and phenolic acids. A strategy that integrates ultrahigh-performance liquid chromatography–electrospray ionization mass spectrometry (UHPLC–ESI/MS) and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) spatial metabolomics analysis was proposed and applied to different parts of T. hemsleyanum for the first time. A total of 132 compounds were tentatively identified, and 3, 7, and 24 components were found only in tuberous roots (TRs), fibrous roots (FRs), and leaves, respectively, using UHPLC–ESI/MS. The DESI-MSI results showed that the spatial distribution of flavonoids between the aerial and underground parts was diverse; for example, vitexin-2″-O-glucoside was largely localized in the epidermis and xylem of TRs, while a small amount was restricted to the xylem of the leaf margin and FRs. There was a higher abundance of most organic acids and flavonoids in the leaves than in the underground parts. Some flavonoids showed the same abundance in FRs and TRs, but the levels of most compounds were considerably higher in FRs. It is possible for leaves and FRs to become new medicinal parts of T. hemsleyanum. Through chemometrics statistics analysis, 19 key differential compounds in different parts of T. hemsleyanum were found, and the pharmacological mechanisms of the main differential metabolites were predicted by network pharmacology. This study provides a novel method for the medicinal development of T. hemsleyanum, showing its great potential in the development of medicinal resources.

Proteomic Analysis of Dorsal Root Ganglia in a Mouse Model of Paclitaxel-Induced Neuropathic Pain.

Paclitaxel is a chemotherapy drug widely used for the treatment of various cancers based on its ability to potently stabilize cellular microtubules and block division in cancer cells. Paclitaxel-based treatment, however, accumulates in peripheral system sensory neurons and leads to a high incidence rate (over 60%) of chemotherapy induced peripheral neuropathy. Using an established preclinical model of paclitaxel-induced peripheral neuropathy (PIPN), we examined proteomic changes in dorsal root ganglia (DRG) of adult male mice that were treated with paclitaxel (8 mg/kg, at 4 injections every other day) relative to vehicle-treated mice. High throughput proteomics based on liquid chromatography electrospray ionization mass spectrometry identified 165 significantly altered proteins in lumbar DRG. Gene ontology enrichment and bioinformatic analysis revealed an effect of paclitaxel on pathways for mitochondrial regulation, axonal function, and inflammatory purinergic signaling as well as microtubule activity. These findings provide insight into molecular mechanisms that can contribute to PIPN in patients.

Effectiveness and Biochemical Impact of Flubendiamide and Flonicamid Insecticides against Bemisia tabaci (Hemiptera: Aleyrodidae) and Residue Dissipation in Cherry Tomato Plants and Soil under Greenhouse Conditions

Abstract We investigated the effectiveness and biochemical impact of the insecticides flubendiamide and flonicamid compared with azadirachtin and acetamiprid against the whitefly Bemisia tabaci (Grennadius) (Hemiptera: Aleyrodidae) infesting cherry tomato (Solanum lycopersicum var. cerasiforme L.) grown under greenhouse conditions. The dissipation of both insecticides in the plants and in the soil also was determined using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) and liquid chromatography–electrospray ionization–mass spectrometry methods. Both insecticides were more effective for reducing B. tabaci populations than were either acetamiprid or azadirachtin. Biochemical analysis revealed that esterase may play an important role in whitefly adaptation to flubendiamide and flonicamid. The QuEChERS method was determined suitable for quickly detecting residues of flubendiamide and flonicamid in complex matrices. The recovery rates on tomato fruit samples were 92.8–106.0%, with a relative standard deviation (RSD) range of 0.46–2.65%. For soil samples, the recovery rates were 81.3–95.7% with RSDs of 1.20–3.86%. We further determined that flubendiamide had dissipation half-lives of 3.13, 3.63, and 3.68 d in tomato fruit, tomato leaves, and soil, respectively. Flonicamid had half-lives of 4.25, 3.54, and 2.60 d in fruit, leaves, and soil, respectively. These results suggest that preharvest intervals of 3 and 7 d are appropriate for flubendiamide and flonicamid, respectively, in cherry tomato production. The risk quotient was >1 by the day 5 after application; however, that value declined to <1 on day 7 after application, indicating little long-term risk to human health.

Proteomic analysis of dorsal root ganglia in a mouse model of paclitaxel-induced neuropathic pain.

Paclitaxel is a chemotherapy drug widely used for the treatment of various cancers based on its ability to potently stabilize cellular microtubules and block division in cancer cells. Paclitaxel-based treatment, however, accumulates in peripheral system sensory neurons and leads to a high incidence rate (over 50%) of chemotherapy induced peripheral neuropathy in patients. Using an established preclinical model of paclitaxel-induced peripheral neuropathy (PIPN), we examined proteomic changes in dorsal root ganglia (DRG) of adult male mice that were treated with paclitaxel (8 mg/kg, at 4 injections every other day) relative to vehicle-treated mice. High throughput proteomics based on liquid chromatography electrospray ionization mass spectrometry identified 165 significantly altered proteins in lumbar DRG. Gene ontology enrichment and bioinformatic analysis revealed an effect of paclitaxel on pathways for mitochondrial regulation, axonal function, and inflammatory purinergic signaling as well as microtubule activity. These findings provide insight into molecular mechanisms that can contribute to PIPN in patients.

Streamlined Arsenolipid Identification via Direct Arsenic Detection Using RPLC-ESI-QTOF-MS with Collision-Induced Dissociation.

Arsenolipids are organoarsenicals with a long aliphatic chain that have been identified in a wide array of marine organisms. Precise analysis of arsenolipids is crucial for evaluating their toxicity, ensuring food safety, monitoring the environment, and gaining insights into the evolution of arsenic biogeochemistry. However, the discovery of new arsenolipids is often impeded by existing analytical challenges, notably the need for multiple instruments, such as the combination of liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) and inductively coupled plasma mass spectrometry (LC-ICP-MS). This study introduces a high-throughput untargeted analytical method on the basis of an unsophisticated instrumental configuration, LC-ESI-MS with collision-induced dissociation (CID) at 200 eV. This approach provides efficient dissociation of arsenic atoms from their precursor lipids and direct detection of the organic-bound arsenic as monatomic cations, As+. Application of this method has shown promise in rapidly characterizing arsenolipids in diverse samples, which has led to the discovery of a wide range of novel arsenolipids, including seven previously unidentified thioxoarsenolipids in ancient marine sediments.

Geographical distribution-based differentiation of cultivated Angelica dahurica, exploring the relationship between the secretory tract and the quality

Based on geographical distribution, cultivated Chinese Angelica dahurica has been divided into Angelica dahurica cv. ‘Hangbaizhi’ (HBZ) and Angelica dahurica cv. ‘Qibaizhi’ (QBZ). Long-term geographical isolation has led to significant quality differences between them. The secretory structure in medicinal plants, as a place for accumulating effective constituents and information transmission to the environment, links the environment with the quality of medicinal materials. However, the secretory tract differences between HBZ and QBZ has not been revealed. This study aimed to explore the relationship between the secretory tract and the quality of two kinds of A. dahurica. Root samples were collected at seven development phases. High-Performance Liquid Chromatography (HPLC) and Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI-MSI) were used for the content determination and spatial location of coumarins. Paraffin section was used to observe and localize the root secretory tract. Origin, CaseViewer, and HDI software were used for data analysis and image processing. The results showed that compared to QBZ, HBZ, with better quality, has a larger area of root secretory tracts. Hence, the root secretory tract can be included in the quality evaluation indicators of A. dahurica. Additionally, DESI-MSI technology was used for the first time to elucidate the temporal and spatial distribution of coumarin components in A. dahurica root tissues. This study provides a theoretical basis for the quality evaluation and breeding of improved varieties of A. dahurica and references the DESI-MSI technology used to analyze the metabolic differences of various compounds, including coumarin and volatile oil, in different tissue parts of A. dahurica.

Eremophila purpurascens: Anti-oxidant, Anti-hyperglycemic, and Hepatoprotective Potential of Its Polyphenolic Rich Leaf Extract and Its LC-ESI-MS/MS Chemical Characterization and Standardization.

The genus Eremophila, despite comprising more than 250 species, has scarce literature studies that could be traced concerning the chemical profile and bioactivity of Eremophila purpurascens. The current study targets the investigation of the in vitro and in vivo anti-oxidant, anti-hyperglycemic, and hepatoprotective potential of the polyphenol-rich leaf extract of E. purpurascens (EP). EP showed promising total anti-oxidant capacity with IC50 values of 106 and 114 μg/mL in 2,2'-azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS) and diphenyl-1-picrylhydrazyl (DPPH) assays, respectively, with total anti-oxidant capacities of 331, 245, and 1767 μmol/g in ABTS, DPPH, and ferric reducing anti-oxidant power assays, respectively. In HepG2 cells, pre-treated with CCl4, a dose of 100 μg/mL EP ameliorated the reduced superoxide dismutase and glutathione levels and total anti-oxidant capacity with values of 312.5 U/mL, 15.47 mg/dL, and 1.03 nmol/mL, respectively. In vitro anti-diabetic evaluation using 3T3-L1 adipocyte culture showed that at a dose of 30 μg/mL, the EP extract elicited a 6.3% decrease in the concentration of glucose (22.4 mmol/L), showing significant amelioration with regard to pioglitazone and insulin. EP also demonstrated elevated serum insulin by 77.78% with a marked reduction in fasting blood glucose level by 64.55% relative to the streptozotocin diabetic rats in vivo. EP also relieved the liver stress markers both in vitro in CCl4 and in vivo in tamoxifen (TAM) models. EP markedly decreased TAM toxicity, as demonstrated by the decline in the liver stress markers, ALT and AST, by 36.1 and 51.1%, respectively. It also relieved the oxidative stress triggered by TAM, as revealed by the reduction in the levels of TBARs and TNF-α by 21.4 and 40%, respectively. Liquid chromatography electrospray ionization mass spectrometry of EP revealed a total of twelve peaks belonging to phenylpropanoids, lignans, and phenolics, where verbascoside and pinoresinol-4-O-β-d-glucoside represented the most abundant secondary metabolites. The docking experiment showed that tri-O-galloyl-hexoside had the best fitting within the NADPH oxidase active sites with binding energy (ΔG = -81.12 kcal/mol). Thus, the plant can be of beneficial value in the control of hyperglycemia in diabetic patients, besides its prophylactic potential against hepatic complications.

Diallyldimethylammonium Chloride (DADMAC) in Water Treated with Poly-Diallyldimethylammonium Chloride (PDADMAC) by Reversed-Phase Ion-Pair Chromatography—Electrospray Ionization Mass Spectrometry

Poly-diallyldimethylammonium (PDADMAC) chloride is a flocculant agent extensively used in water clarification treatments. Commercial polyelectrolyte formulations often contain residual monomer (DADMAC), reaction by-products and other reactants as contaminants that could potentially affect human health. In the present study, we optimized an analytical method based on reversed-phase ion-pair chromatography coupled with mass spectrometry for quantifying ultra-trace levels of DADMAC, without preliminary treatments, in drinking water distributed by the Palermo aqueduct. The method was validated in terms of accuracy (recovery between 80 to 120%), precision (RSD < 10%), linearity range (from 0.5 to 15 µg/L), limit of quantification and limit of detection (LOQ 0.42 µg/L and LOD 0.12 µg/L). DADMAC was detected in all analysed water samples and the concentration ranged from 1.2 to 3.8 µg/L whit a mean value of 1.7 µg/L. To the best of our knowledge, this paper represents the first study concerning DADMAC concentration in water samples collected in Italy and, in this context, this paper can be considered very interesting when comparing future data on DADMAC monitoring in water. Moreover, this is one of a few cases where DADMAC was found in drinking water.

Polybutylene terephthalate-based stationary phase for ion-pair-free reversed-phase liquid chromatography of small interfering RNA. Part 2: Use for selective comprehensive two-dimensional liquid chromatography

With the increasing numbers of nucleic acid-based pharmaceuticals like antisense oligonucleotides (ASO), small interfering ribonucleic acid (siRNA) entering the market, research facilities, pharmaceutical industries and also regulatory authorities have been looking for efficient analytical methods for these synthetic oligonucleotides (ON). Besides of conventional one-dimensional (1D) reversed-phase liquid chromatography with or without ion-pairing (IP-RP-LC, RP-LC), hydrophilic liquid chromatography (HILIC) and mixed-mode chromatography (MMC), two-dimensional (2D) approaches combining two orthogonal chromatographic techniques also become more relevant due to the high structural complexity of oligonucleotides. Recently, we tested a polybutylene terephthalate(PBT)-based stationary phase under ion-pairing free RP mode for the liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) analysis of siRNA (Patisiran). In this study, retention profile and chromatographic orthogonality, respectively, were compared to other LC-modes like HILIC, IP-RPLC, another ion-pair free cholesterol-bonded RPLC and MMC considering their normalized retention times. Finally, because of higher orthogonality, the ion-pairing free PBT-bonded RPLC as first dimension (1D) was hyphenated with HILIC in the second dimension (2D) in a selective comprehensive 2D-LC setup leading to an enhanced resolution for peak purity evaluation of the main ON entities.

Widespread occurrence of in-source fragmentation in the analysis of natural compounds by LC-ESI-MS.

The In-Source Fragmentation (ISF) of analyte or co-eluting substances produces unintentional fragment ions, which hampers the identification and quantification by liquid chromatography-mass spectrometry (LC-MS). Natural compounds derived from plants also contain fragile moieties that may undergo ISF. However, the characteristics of ISF of natural compounds in LC-MS are still unclear. The ISF behavior of 214 natural compounds was assayed in liquid chromatography-Q/orbitrap mass spectrometry in electrospray ionization mode (ESI) and the extent of ISF was evaluated. Up to 82% of tested compounds undergo ISF and half of the tested natural compounds that contain more than one fragile moiety underwent successive and severe ISF to generate serial structurally-related ISF products. The major ISF-altering moieties for natural compounds were hydroxyl, lactone, glycosyl, and ether, resulting in neutral loss of H2 O or CO, deglycosylation, or cleavage of ether bond, respectively. Some compounds such as terpenoids undergo severe ISF and less than 1% parent form can be observed. For natural compounds, the ISF product with similar structures more likely to cause interference in analysis because the ISF products may share identical mass-to-charge ratio and similar MS2 fragmentation patterns with precursor ions of the homologs in plants. Furthermore, the severe ISF may cause a false negative in the identification of the parent form. In summary, ISF was a highly frequent phenomenon for analysis of natural compounds by LC-ESI-MS, extensive and successive ISF of natural products may cause misannotation and misidentification with the homologs in plants. It should raise awareness of ISF interference during the analysis of natural compounds.

Rapid visual characterization of alkaloid changes in traditional processing of Tibetan medicine Aconitum pendulum by high-performance thin-layer chromatography coupled with desorption electrospray ionization mass spectrometry imaging.

Radix Aconiti, also known as Tie-bang-chui (TBC), Pang-a-na-bao, and Bang-na, is a typical aconitum Tibetan medicine and a perennial herb of the genus Aconitum pendulum Busch. and A. flavum Hand. -Mazz. dry roots. It has high toxicity and remarkable efficacy; as such, it is a typical "highly toxic and effective" drug that needs be processed and used. Processing methods of this Tibetan medicine include non-heating of highland barley wine (HBW) and fructus chebulae soup (FCS). This work aimed to understand differences in chemical composition between non-heat processed products and raw TBC. In this study, high-performance thin-layer chromatography (HPTLC) and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) were used to analyze the chemical composition of TBC processed by FCS (F-TBC) and HBW (H-TBC). The MRM mode of HPLC-QqQ-MS/MS was selected to determine the changes of several representative alkaloids to comparison with the former results. A total of 52 chemical constituents were identified in raw and processed products, and the chemical composition of F-TBC and H-TBC changed slightly compared with that of raw TBC. The processing mechanism of H-TBC was also different from that of F-TBC, which might be related to the large amount of acidic tannins in FCS. It was found that the content of all six alkaloids decreased after processing by FCS, and all five alkaloids decreased except aconitine increased after processing by HBW. The combination of HPTLC and DESI-MSI could be an effective method for rapid identification of chemical components and changing rules in ethnic medicine. The wide application of this technology provides not only an alternative method for the traditional separation and identification of secondary metabolism but also a reference for research on the processing mechanism and quality control of ethnic medicine.

In-vitro and in-vivo anti-leishmanial activity of the hanging sedge flavonoids based on bio- guided fractionation assay.

As a major public health issue, cutaneous leishmaniasis (CL) has a number of complications, including drug resistance and poor response to conventional treatments. Over the last decade, research on natural sources for finding new anti-leishmanial agents has been a critical part of tropical disease research. Natural products also should be regarded as one of the most valuable applications for CL infection drug development. In this study, we assessed the in-vitro and in-vivo anti-leishmanial potential of Carex pendula Huds. (hanging sedge) methanolic extract and its fractions against Leishmania major produced cutaneous infection. Although the methanolic extract and its fractions exhibited suitable activity, the ethyl acetate fraction showed the best activity (with the half maximal inhibitory concentration IC50 = 1.627±0.211 mg/mL). The toxicity and selectivity indices (SI) of all samples were determined in murine peritoneal macrophage cells (J774A.1) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. The flavonoid components of the ethyl acetate fraction were identified using liquid chromatography electrospray ionization mass spectrometry (LC-ESI MS/MS). Nine chemical compounds were identified in this fraction, including three flavonols, four flavanonols, and two flavan derivatives. L. major infected mice were used as an in-vivo model because the methanolic extract was effective against L. major promastigotes in the mammalian cell line J774A.1 with SI=2.514 (tail lesion size model). In-silico analysis of identified compounds also revealed a favorable interaction between compounds 2-5 and L. major protein targets (3UIB, 4JZX, 4JZB, 5L4N, 5L42). According to the findings of this study, the ethyl acetate fraction (as flavonoid fraction) exhibited considerable in-vitro anti-leishmanial activity.

Assessing the Effectiveness of Chemical Marker Extraction from Amazonian Plant Cupuassu (Theobroma grandiflorum) by PSI-HRMS/MS and LC-HRMS/MS.

Employing a combination of liquid chromatography electrospray ionization and paper spray ionization high-resolution tandem mass spectrometry, extracts from cupuassu (Theobroma grandiflorum) pulp prepared with either water, methanol, acetonitrile or combinations thereof were subjected to metabolite fingerprinting. Among the tested extractors, 100% methanol extracted preferentially phenols and cinnamic acids derivatives, whereas acetonitrile and acetonitrile/methanol were more effective in extracting terpenoids and flavonoids, respectively. And while liquid chromatography- mass spectrometry detected twice as many metabolites as paper spray ionization tandem mass spectrometry, the latter proved its potential as a screening technique. Comprehensive structural annotation showed a high production of terpenes, mainly oleanane triterpene derivatives. of the mass spectra Further, five major metabolites with known antioxidant activity, namely catechin, citric acid, epigallocatechin-3'-glucuronide, 5,7,8-trihydroxyflavanone, and asiatic acid, were subjected to molecular docking analysis using the antioxidative enzyme peroxiredoxin 5 (PRDX5) as a model receptor. Based on its excellent docking score, a pharmacophore model of 5,7,8-trihydroxyflavanone was generated, which may help the design of new antioxidants.

Hydrophilic interaction liquid chromatography–electrospray ionization mass spectrometry combined with fabric phase sorptive extraction for therapeutic drug monitoring of pioglitazone, repaglinide, and nateglinide in human plasma

Polypharmacy in type 2 diabetes is an issue of major concern as the prescription of multiple medi-cations for the management of diabetes-associated comorbidities can lead to drug-to-drug interactions, which can pose serious risks to patients’ health. Within this context, the development of bioanalytical methods for monitoring the therapeutic levels of antidiabetic drugs is notably useful to ensure patients’ safety. In the present work, a liquid chromatography–mass spectrometry method for the quantitation of pioglitazone, repaglinide, and nateglinide in human plasma is described. Sample preparation was performed by fabric phase sorptive extraction (FPSE), and hydrophilic interaction liquid chromatography (HILIC) was implemented for the chromatographic separation of the analytes, using a ZIC®-cHILIC analytical column (150 × 2.1 mm, 3 µm) under isocratic elution. The mobile phase consisted of 10 mM ammonium formate aqueous solution (pH = 6.5)/ acetonitrile, 10/90 v/v, and was pumped at a flow rate of 0.2 mL min−1. Design of Experiments was used during the development of the sample preparation method to gain deeper insight into the effect of various experimental parameters on extraction efficiency, their potential interactions and to optimize the recovery rates of the analytes. The linearity of the assay was assessed over the ranges of 25 to 2000, 6.25 to 500, and 125 to 10000 ng mL−1 for pioglitazone, repaglinide, and nateglinide, respectively. The presented method was fully validated and can be used for the therapeutic monitoring of the targeted analytes in human plasma samples.

Ionic Liquid-Dispersive Micro-Extraction and Detection by High Performance Liquid Chromatography-Mass Spectrometry for Antifouling Biocides in Water.

A simple analytical method was developed and evaluated for the determination of two antifouling biocides using an ionic liquid-dispersive liquid-liquid micro-extraction (IL-DLLME) and a high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis. Irgarol 1051 and Sea-Nine 211 were extracted from deionized water, lake water, and seawater using IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF6]) and ethyl acetate as the extraction solvent and the dispersion solvent. Several factors were considered, including the type and volume of extraction and dispersive solvent, IL amount, sample pH, salt effect, and cooling temperature. The developed method resulted in a recovery range of 78.7-90.3%, with a relative standard deviation (RSD, n = 3) less than 7.5%. The analytes were enriched greater than 40-fold, and the limits of detection (LOD) for two antifouling biocides were 0.01-0.1 μg L-1. The method was effectively applied for the analysis of real samples of freshwater as well as samples of seawater.

Characterization and Comparison of Steroidal Glycosides from Polygonatum Species by High-Performance Liquid Chromatography–Electrospray Ionization Mass Spectrometry

Polygonatum species have been used as traditional medicines and functional foods in Asia and Europe since ancient times. In this study, a fast and simple method based on liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) was developed to systematically analyze and identify the steroidal glycosides in four major Polygonatum species distributed in Japan, including P. odoratum, P. falcatum, P. macranthum, and P. sibiricum. As a result, 31 steroidal glycosides were tentatively identified, including 18 known and 13 previously unreported glycosides. Their structures were identified by the interpretation of chromatographic behavior and ESI-MS fragmentation patterns. The identification of 31 steroidal glycosides was indicative of a common biogenetic pathway in Polygonatum species. Our study disclosed the chemical profiling of steroidal glycosides in the plants of Polygonatum species, which will benefit better phytochemotaxonomical and phytochemical understanding and quality control for their medicinal usage.

Simultaneous Determination of Glibenclamide and Silymarin Released from Chitosan Microparticles by HPLC-ESI-MS Technique: Method Development and Validation.

The study aim was to develop and validate a high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC-ESI-MS) method to simultaneously determine glibenclamide (Gli) and silymarin (Sil) released from chitosan (CS) microparticles in aqueous solutions. The CS microparticles were synthesized using an ionic gelation method, and their morphology, swelling degree, encapsulation efficiency and active substance release were investigated. Gli and Sil were loaded in different concentrations, and their identification and quantification were performed using the HPLC-ESI-MS method, which was further validated. The drugs’ characteristic m/z was found in the higher intensity of retention time (Rt) (Gli, 8.909 min; Sil A, 5.41 min; and Sil B, 5.66 min). The method selectivity and precision are very good, and the blank solution proved no interference. The linearity of the answer function is very good for Sil A (R2 = 1), Sil B (R2 = 0.9998) and Gli (R2 = 0.9991). For Gli, we obtained a limit of detection (LOD) = 0.038 mg/mL and limit of quantification (LOQ) = 1.275 mg/mL; for Sil A, a LOD = 0.285 mg/mL and LOQ = 0.95 mg/mL; and for Sil B, a LOD = 0.045 mg/mL and LOQ = 0.15 mg/mL. A high-resolution HPLC-ESI-MS method was developed and validated, which allowed the simultaneous determination of Gli and Sil loaded in CS microparticles, in a concentration range of 0.025–1 mg/mL.

Assay of Endocannabinoid Uptake.

Endocannabinoids at nanomolar physiological concentrations cross cellular membranes by facilitated diffusion, a process that can be studied by measuring transport kinetics and endocannabinoid trafficking employing radioligands and mass spectrometry. Here, we describe radiosubstrate-based assays using arachidonoyl[1-3H]ethanolamine and 2-arachidonoyl[1,2,3-3H]glycerol to measure cellular endocannabinoid uptake in a three-phase assay with human U937 cells. Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS)-based lipidomics was used to interrogate the roles of serum and albumin for endocannabinoid trafficking in U937 cells.