Quadrupole Orbitrap Mass Spectrometry Research Articles

Comparative Research of Chemical Profiling in Different Parts of Fissistigma oldhamii by Ultra-High-Performance Liquid Chromatography Coupled with Hybrid Quadrupole-Orbitrap Mass Spectrometry.

The roots of Fissistigma oldhamii (FO) are widely used as medicine with the effect of dispelling wind and dampness, promoting blood circulation and relieving pains, and its fruits are considered delicious. However, Hakka people always utilize its above-ground parts as a famous folk medicine, Xiangteng, with significant differences from literatures. Studies of chemical composition showed there were multiple aristolactams that possessed high nephrotoxicity, pending evaluation research about their distribution in FO. In this study, a sensitive, selective, rapid and reliable method was established to comparatively perform qualitative and semi-quantitative analysis of the constituents in roots, stems, leaves, fruits and insect galls, using an Ultra-High-Performance Liquid Chromatography coupled with Hybrid Quadrupole Orbitrap Mass Spectrometry (UPLC-Q-Exactive Orbitrap MS, or Q-Exactive for short). To make more accurate identification and comparison of FO chemicals, all MS data were aligned and screened by XCMS, then their structures were elucidated according to MSn ion fragments between the detected and standards, published ones or these generated by MS fragmenter. A total of 79 compounds were identified, including 33 alkaloids, 29 flavonoids, 11 phenylpropanoids, etc. There were 54 common components in all five parts, while another 25 components were just detected in some parts. Six toxic aristolactams were detected in this experiment, including aristolactam AII, AIIIa, BII, BIII, FI and FII, of which the relative contents in above-ground stems were much higher than roots. Meanwhile, multivariate statistical analysis was performed and showed significant differences both in type and content of the ingredients within all FO parts. The results implied that above-ground FO parts should be carefully valued for oral administration and eating fruits. This study demonstrated that the high-resolution mass spectrometry coupled with multivariate statistical methods was a powerful tool in compound analysis of complicated herbal extracts, and the results provide the basis for its further application, scientific development of quality standard and utilization.

UHPLC-UV-Q-Orbitrap HRMS combined with machine learning algorithms reveals the chemical markers of Euodiae Fructus among closely related cultivars

Euodiae Fructus (EF, the fruit of Tetradium ruticarpum) belongs to the family Rutaceae which has a complex genetic background, making classification a challenge. In order to classify the three closely related cultivars (small flower EF, medium flower EF, and big flower EF) and simplify the identification procedure in the future, an approach integrating ultra-high performance liquid chromatography-ultraviolet spectrum-hybrid quadrupole-Orbitrap high resolution mass spectrometry (UHPLC-UV-Q-Orbitrap HRMS) with machine learning algorithms was developed. Orthogonal partial least squares-discriminant analysis (OPLS-DA) and random forest (RF) were used to assort the processed EF products and select the chemical markers to differentiate among the three EF cultivars, respectively. Then the thresholds of classification were determined using the eXtreme Gradient Boosting (XGboost) model based on the quantitative data of chemical markers by the UHPLC-Q-Orbitrap HRMS. The results demonstrated that the approach successfully discriminated among three closely related cultivars of EF, and five chemical markers (neochlorogenic acid, (+)-catechin, chlorogenic acid, dehydroevodiamine, and limonin) were selected. Thresholds were obtained to classify the three cultivars. If the content of neochlorogenic acid was greater than 7.52 mg/g, the sample belonged to small flower EF, otherwise, it belonged to medium flower EF or big flower EF. Furthermore, if the content of dehydroevodiamine was greater than 3.84 mg/g, the sample was medium flower EF, otherwise, it was big flower EF. In general, this research provides a novel strategy for the discrimination of Euodiae Fructus cultivars to avoid misapplication and possible side effects.

Profile chemical compounds and antioxidant activity of Korean commercial vinegars produced by traditional fermentation

Ultra-high-performance liquid chromatography coupled with linear trap quadrupole-orbitrap mass spectrometry (UHPLC-LTQ–Orbitrap MS) with multivariate statistical analysis was applied for the metabolite profiling and assessing antioxidant activity of ten commercial vinegars produced by traditional fermentation techniques. Totally, 28 metabolites including three organic acids, three phenolic acids, 11 flavonoids, nine lipids and fatty acids, 6-methoxymellein, and tyrosyl-valine, were identified in the ten vinegars. Using principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA), vinegar samples were differentiated based on raw materials used in their production. Based on the PC1 (42.10%) and PC2 (9.86%), mulberry fruit vinegar (OV) and citrus vinegar (CV) were classified as rest vinegars. Fruit vinegars were found to be rich in metabolites and antioxidant properties, as compared to grain vinegars. OV had the highest content of the quercetin derivatives and phenolic acids, and showed strongest antioxidant activity. Of the 28 metabolites identified, quercetin-3-O-rhamnoside-7-O-glucoside and quercetin-3-O-glucosyl-rutinoside were determined to be the main contributors to antioxidant activity in vinegars. The current study suggests that metabolite profiling by UHPLC–MS can be used to illuminate compounds associated with antioxidant properties as well as selection for vinegar type with the high content of bioactive metabolite profiles.

Untargeted Ultrahigh-Performance Liquid Chromatography-Hybrid Quadrupole-Orbitrap Mass Spectrometry (UHPLC-HRMS) Metabolomics Reveals Propolis Markers of Greek and Chinese Origin.

Chemical composition of propolis depends on the plant source and thus on the geographic and climatic characteristics of the site of collection. The aim of this study was to investigate the chemical profile of Greek and Chinese propolis extracts from different regions and suggest similarities and differences between them. Untargeted ultrahigh-performance liquid chromatography coupled to hybrid quadrupole-Orbitrap mass spectrometry (UHPLC-HRMS) method was developed and 22 and 23 propolis samples from Greece and China, respectively, were analyzed. The experimental data led to the observation that there is considerable variability in terms of quality of the distinctive propolis samples. Partial least squares - discriminant analysis (PLS-DA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) models were constructed and allowed the identification of significant features for sample discrimination, adding relevant information for the identification of class-determining metabolites. Chinese samples overexpressed compounds that are characteristic of the poplar type propolis, whereas Greek samples overexpress the latter and the diterpenes characteristic of the Mediterranean propolis type.

Analytical Methodologies for the Characterization and Analysis of the Parent Compound and Phase I Metabolites of 4F-MDMB-BICA in Human Microsome, Urine, and Blood Samples.

4F-MDMB-BICA is one of the most dangerous new illicit synthetic cannabinoids (SCs) in 2020. Consumption of 4F-MDMB-BICA has been associated with a number of death cases and related serious adverse health effects in Hungary. Therefore, the use of reliable analytical methods to confirm the intake of 4F-MDMB-BICA is an important issue in forensic practice. Besides the detection of the parent compounds of SCs, the screening of their metabolites provides a reliable confirmation of their consumption, in particular, when the parent compound is under the limit of detection. To the best of our knowledge, this is the first report describing the identification of metabolites of 4F-MDMD-BICA after treatment with pooled human liver microsome (pHLM) and in human urine and blood samples using the combination of data obtained by comprehensive ultra-high performance liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC–HRMS) and semi-targeted UHPLC–HRMS-MS methods. Finally, our routine UHPLC coupled with triple-quadrupole tandem low-resolution mass spectrometry method for screening urine and blood SCs was improved by adding the parent compound and selected main biomarkers of 4F-MDMD-BICA. From the pHLM assay of 4F-MDMD-BICA, 30 phase I metabolites were characterized and structural information thus obtained provided the basis of further identification of in vivo urine and blood metabolites. Overall, 20 urinary and 13 blood in vivo metabolites of 4F-MDMD-BICA have been identified by the investigation of five authentic urine and two blood samples. The ester hydrolysis metabolite was selected as a reliable primary biomarker in urine and blood. As secondary targets, urinary mono-hydroxylation metabolite and ester hydrolysis + dehydrogenation metabolite in blood were recommended due to their abundance and selectivity. Overall, the main phase I metabolites of 4F-MDMD-BICA were successfully characterized, and our routine analytical method with related sample preparation procedure provided a reliable analytical tool for screening both 4F-MDMD-BICA and its selected metabolites in urine and blood samples.

Application of Lipidomics for Assessing Tissue Lipid Profiles of Patients With Squamous Cell Carcinoma.

Background: Lipid metabolism disorders play a key role in the pathogenesis of squamous cell carcinoma (SqCC). Herein we used lipidomics to study the tissue lipid profiles of 40 patients with SqCC. Methods: Lipidomics, based on ultrahigh-performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry, was applied to identify altered lipid metabolites between tumor and adjacent noninvolved tissues (ANIT), and partial least squares-discriminant analysis model facilitated the identification of differentially abundant lipids. The area under the receiver operator characteristic curve and variable importance in projection scores of the aforementioned model were calculated to select lipid profiles. Metabolic pathway analyses were completed using Kyoto Encyclopedia of Genes and Genomes and MetaboAnalyst. Results: Differences in lipid profiles were found between tumor and ANIT, early- and advanced-stage SqCC, and positive and negative lymph node metastases. The lipid profile panel was composed of five lipids—PC(44:4), diacylglycerol(36:5), sphingomyelin(d18:1/20:0), phosphatidylinositol(46:7), and HexCer-AP(t8:0/32:2 + O)—and could effectively differentiate between tumor and ANIT. Further, pathway analyses revealed alterations in several lipid metabolism pathways, including glycerophospholipid metabolism, glycosylphosphatidylinositol anchor biosynthesis, linoleic acid metabolism, glycerolipid metabolism, and sphingolipid metabolism. Conclusion: Our data revealed several changes in the tissue lipid profiles of patients with SqCC; moreover, we identified a lipid profile panel that could effectually distinguish tumor tissues from ANIT. We believe that our results provide new insights into the biological behavior of lung SqCC.

Comparative Metabolomics Revealing the Metabolic Responses of Pathogenic Bacteria to Different Antibiotics.

This protocol describes the extraction and analysis of bacterial metabolites to determine the metabolic changes pertaining to their responses to different types of antibiotics. Polar metabolites are extracted using a methanol-based extraction. Sensitive, specific, and semi-quantitative metabolite analysis was performed using a high-performance liquid chromatography coupled to a high-resolution quadrupole-Orbitrap mass spectrometry. Using our example bacteria as a demonstration, 14,528 metabolic features can be detected, and 1448 metabolites were putatively identified via basic database search. Additionally, 93 metabolites can be confidently identified via high-purity standards. Statistical analysis of these metabolites can pinpoint crucial changes in metabolic states of pathogens going through antibiotic treatment, which may assist our understanding of the antibiotic mechanism of actions from a metabolic perspective.

Isolation and Identification of Chemical Constituents from Zhideke Granules by Ultra-Performance Liquid Chromatography Coupled with Mass Spectrometry.

Chemical constituents from Zhideke granules were rapidly isolated and identified by ultra-performance liquid chromatography (UPLC) coupled with hybrid quadrupole-orbitrap mass spectrometry (MS) in positive and negative ion modes using both full scan and two-stage threshold-triggered mass modes. The secondary fragment ion information of the target compound was selected and compared with the compound reported in databases and related literatures to further confirm the possible compounds. A total of 47 chemical constituents were identified from the ethyl acetate extract of Zhideke granules, including 21 flavonoids and glycosides, 9 organic acids, 4 volatile components, 3 nitrogen-containing compounds, and 10 other compounds according to the fragmentation patterns, relevant literature, and MS data. The result provides a new method for the analysis of chemical constituents of Zhideke granules which laid the foundation for quality control and the study of pharmacodynamic materials of Zhideke granules.

Automated micro-solid-phase extraction clean-up of polycyclic aromatic hydrocarbons in food oils for analysis by gas chromatography-orbital ion trap mass spectrometry.

Food can contain unwanted compounds and need to be analyzed for compounds like carcinogenic polycyclic aromatic hydrocarbons to ensure consumer safety. The analytes need to be extracted from the sample matrix and cleaned-up to enable detection. However, established methods for clean-up are labor intensive and have a high expenditure on organic solvents. Here, we show a newly developed micro-solid-phase extraction cartridge method to automate the clean-up for analysis of polycyclic aromatic hydrocarbons in sunflower oil using gas chromatography with quadrupole-orbitrap mass spectrometry with a TriPlus autosampler. This automated micro-solid-phase extraction cartridge method needs only 4 μL of vegetable oil sample and requires only 360 μL acetonitrile for elution, and, therefore, it needs only small amounts of organic solvent. Two different micro-solid-phase extraction cartridge methods were developed, one using two commercially available cartridges with florisil and octadecylsilane/Z-Sep/CarbonX, and the other method using one commercially available cartridge with florisil followed by one self-made cartridge with octadecylsilane/Z-Sep. The latter method showed successful lipid removal and was further validated for 22 of 24 polycyclic aromatic hydrocarbon compounds in sunflower oil at a spiked level of 1090μg/kg with recoveries ranging from 53 to 118% and relative standard deviation below 22%. This method shows promising short-time clean-up with low expenditure of solvents.

Integrated UPLC-MS/MS and UHPLC-Q-orbitrap HRMS Analysis to Reveal Pharmacokinetics and Metabolism of Five Terpenoids from Alpiniae oxyphyllae Fructus in Rats.

Alpiniae oxyphyllae Fructus (AOF), a traditional Chinese medicine (TCM), is widely used in the treatment of urinary, gastrointestinal and neurologic diseases in China. Although terpenoids are the main active ingredients of AOF, there are few researches on their pharmacokinetics and metabolism. In this study, a sensitive, rapid, accurate and novel ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established to evaluate the pharmacokinetic behavior of five terpenoids (oxyphyllenodiol B, (4S*,5E,10R*)-7-oxo-tri-nor-eudesm-5-en-4β-ol, 7-epi-teucrenone, (+)- (4R,5S,7R)-13-hydroxynootkatone, (E)-labda-12,14-dien-15(16)-olide-17-oic acid) in rats after oral administration of AOF extracts. 27 metabolic metabolites of the five terpenoids were identified by ultra high performance liquid chromatography -Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry (UHPLC-Q-Orbitrap HRMS) based on precise mass and fragment ions. The established pharmacokinetic analysis method showed good linearity over a wide concentration range, and the lower quantitative limit (LLOQ) ranged from 0.97 to 4.25 ng/mL. Other validation parameters were within the acceptable range. In addition, 27 metabolites were identified in plasma, urine and feces samples, and the metabolic pathways of five terpenoids were mainly focused on glucoside conjugation, dehydration, desaturation and glycine conjugation. This is the first study on the pharmacokinetics and metabolism of five terpenoids in AOF, illuminating the disposal process of terpenoids in vivo. It was expected that the results of this study would provide some references for the apprehension of the action mechanism and the further pharmacological study of five terpenoids in AOF.

Comprehensive analysis of Huanglian Jiedu decoction: Revealing the presence of a self-assembled phytochemical complex in its naturally-occurring precipitate

The current study presents a comprehensive analysis to explore the compositions of both the supernatant and naturally-occurring precipitate of Huanglian Jiedu decoction employing ultra-high-performance liquid chromatography hyphenated with quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). Totally 109 constituents (32 alkaloids, 39 flavonoids, 12 iridoids, 9 phenolic acids, and 17 other compounds) were identified from accurate-mass measurements in full-scan MS/data-dependent MS/MS mode of acquisition. Furthermore, a quantitative method was developed for determination of 14 marker compounds in Huanglian Jiedu decoction. Experimental results revealed that all of these marker compounds were present in both the supernatant and naturally-occurring precipitate. Most notably, the contents of baicalin and berberine were significantly higher in the naturally-occurring precipitate than supernatant, presumably due to self-assembly complexation. The formation of the baicalin/berberine complex was comprehensively investigated by electrospray ionization (ESI)-MS, nuclear magnetic resonance (NMR), ultraviolet-visible (UV–vis), Fourier transform infrared (FTIR), and fluorescence spectroscopy, etc. The morphology and size distribution of the baicalin/berberine self-assembled nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). This study provides fundamental scientific evidence of the presence of a self-assembled phytochemical complex in the naturally-occurring precipitate, enabling better understanding of Huanglian Jiedu decoction.

Cloning, Yeast Expression, and Characterization of a β-Amyrin C-28 Oxidase (CYP716A249) Involved in Triterpenoid Biosynthesis in Polygala tenuifolia.

Polygala tenuifolia Willd. is a traditional Chinese herbal medicine that is widely used in treating nervous system disorders. Triterpene saponins in P. tenuifolia (polygala saponins) have excellent biological activity. As a precursor for the synthesis of presenegin, oleanolic acid (OA) plays an important role in the biosynthesis of polygala saponins. However, the mechanism behind the biosynthesis of polygala saponins remains to be elucidated. In this study, we found that CYP716A249 (GenBank: ASB17946) oxidized the C-28 position of β-amyrin to produce OA. Using quantitative real-time PCR, we observed that CYP716A249 had the highest expression in the roots of 2-year-old P. tenuifolia, which provided a basis for the selection of samples for gene cloning. To identify the function of CYP716A249, the strain R-BE-20 was constructed by expressing β-amyrin synthase in yeast. Then, CYP716A249 was co-expressed with β-amyrin synthase to construct the strain R-BPE-20 by using the lithium acetate method. Finally, we detected β-amyrin and OA by ultra-HPLC-Q Exactive hybrid quadrupole-Orbitrap high-resolution accurate mass spectrometry and GC-MS. The results of this study provide insights into the biosynthesis pathway of polygala saponins.

The Pharmacokinetics, Tissue Distribution, Metabolism, and Excretion of Pinostrobin in Rats: Ultra-High-Performance Liquid Chromatography Coupled With Linear Trap Quadrupole Orbitrap Mass Spectrometry Studies.

Pinostrobin is a natural flavonoid found in various plants, well known for its wide range of pharmacological activities. However, there are few reports regarding the pharmacokinetics, tissue distribution, metabolism, and excretion of pinostrobin in rats after oral administration as a single compound. Therefore, we established a method using ultra-high-performance liquid chromatography coupled with linear trap quadrupole orbitrap mass spectrometry (UPLC-LTQ orbitrap-MS/MS) to determine pinostrobin and its metabolites in rat plasma, urine, feces, bile, and tissue homogenates. Pharmacokinetic parameters were measured. The large apparent volume of distribution implied that pinostrobin preferentially bound to tissues and preferably remained within the body. Based on previous pharmacological studies of its antiulcer, anti-HP, anti-inflammatory, and antioxidant activities, pinostrobin is mostly distributed in the gastrointestinal tract, indicating its potential as an effective component of traditional Chinese medicines for the treatment of peptic ulcers. Furthermore, 30 flavonoid metabolites were screened using UPLC-LTQ orbitrap-MS/MS. The metabolism pathways (mainly hydroxylation, demethylation, glucuronidation, and sulfation) of pinostrobin in rats have also been proposed. A small amount of pinostrobin in its parent form is excreted through the urine, feces, and bile, indicating that it is mainly metabolized in vivo. In this study, we systemically investigated the pharmacokinetics, tissue distribution, metabolism, and excretion of pinostrobin in rats. Our results provide a significant basis for the clinical development and application of pinostrobin as well as traditional Chinese medicines containing pinostrobin.

Profiling of phenolic acids and flavonoids in sweet potato (Ipomoea batatas L.) leaves and evaluation of their anti-oxidant and hypoglycemic activities

Sweet potato (Ipomoea batatas L.) leaf phenolic acids (SPLPA) and sweet potato leaf flavonoids (SPLF) were characterized using ultra-high-performance liquid chromatography (UHPLC)-hybrid quadrupole-orbitrap mass spectrometry and UHPLC coupled with a diode array detector. The anti-oxidant and hypoglycemic activities were analyzed using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity and ferric reducing anti-oxidant powder assays, and α-glucosidase and α-amylase inhibitory assays. The mechanism of inhibition of SPLPA and SPLF against α-glucosidase was studied using kinetic analysis. Thirteen phenolic acids were identified in SPLPA, of which three di-caffeoylquinic acids (60.6%) were most prominent. Ten flavonoids were identified in SPLF and astragalin (28.1%) was the major component. Protocatechualdehyde, ethyl caffeate and quercetin were also identified, showing strong anti-oxidant capacities and inhibition of α-glucosidase and α-amylase. Kinetic analysis showed that SPLPA and SPLF both reversibly inhibited α-glucosidase, in a mixed-type manner, with IC50 values of 330 and 250 μg/mL, respectively. The results suggested the potential benefits of using sweet potato leaves.

Characterization of chemical components in the Guanxinning injection by liquid chromatography-mass spectrometry.

Guanxinning injection (GXNI) is widely used in the treatments of cerebral thrombosis, cerebral hemorrhage, sequela, coronary disease, stenocardia, arrhythmia, and so on. For the herbal injections, more components should be characterized and quantified as much as possible to guarantee the drug safety. However, large numbers of the chemical constituents in the GXNI still remain unknown. In this study, ultrahigh performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry (UHPLC-Q Orbitrap HRMS), in combination of nuclear magnetic resonance (NMR), was used to identify the components in GXNI, which led to the identification of 194 compounds. With the aid of solvent partition, more phthalides, diterpenoid quinines, and salvianolic acids were tentatively identified, and minor compounds with the other structural types were also detected. The structural diversity of phthalides and diterpenoid quinones were revealed by the structural network, and six phthalides and 13 diterpenoid quinones were further detected in GXNI with the help of the characteristic fragmentation pattern and structural network. In addition, NMR also revealed the presence of a series of primary metabolites in the GXNI, which could be used as a complimentary approach for the rapid identification of the chemical components in the traditional Chinese medicines (TCM). However, the unknown NMR signals of GXNI needed to be further identified to guarantee the drug safety.

Non-lethal microsampling and rapid identification of multi-residue veterinary drugs in aquacultured fish by direct analysis in real time coupled with quadrupole-Orbitrap high-resolution mass spectrometry

An analytical protocol for the identification of 52 multi-class veterinary drug residues in aquacultured fish has been developed based on direct analysis in real time (DART) coupled with quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS). A “sample-and-release” strategy was adopted where live fishes are captured for non-lethal blood microsampling and then released back into the original farming water. A simple micro liquid-liquid extraction (micro-LLE) was incorporated for the extraction and clean-up of veterinary drug analytes from fish blood samples. The main parameters affecting micro-LLE, DART ionization, and Q-Orbitrap HRMS analysis were systematically studied. Data acquisition was carried out using a synchronous full-scan MS/data-dependent MS/MS (full-scan MS1/dd-MS2) workflow. Suspect screening was conducted by comparing the experimentally measured exact mass of precursor and fragment ions with the custom accurate-mass database and by matching the acquired mass spectra against the mass spectral library. The analytical performance of the developed methodology was assessed in terms of sensitivity, linearity, repeatability, and recovery. The limits of detection (LODs) and quantitation (LOQs) of the 52 analytes were in the range of 0.5–20 μg/L and 2–50 μg/L, respectively. The matrix effect ratios ranged from –23.5% to 25.9%. The developed approach demonstrated promising potential for rapid, real-time monitoring of veterinary drug residues to ensure food safety and consumer health.

Using serum peptidomics to discovery the diagnostic marker for different stage of ulcerative colitis

The use of peptidomics to find diagnostic markers has attracted increasing clinical attention. Ulcerative colitis (UC) is a type of inflammatory bowel disease, and the traditional auxiliary diagnostic technique is colonoscopy. However, this invasive method is not effective in distinguishing between patients with endoscopic remission and healthy people, which carries the risk of delayed diagnosis of UC. In this study, we used peptidomics to find serum diagnostic markers for different stages of UC. A total of 78 serum samples were collected to form a training set (60 samples) and a testing set (18 samples). Among them, patients with active UC, remitting UC and healthy people accounted for one third each. The nano-liquid chromatography coupled with hybrid linear trap quadrupole orbitrap mass spectrometry was used for detection of low molecular weight peptides in serum. According to the protein database search and de novo sequencing algorithm, forty peptides were simultaneously identified in all samples. Six biomarker peptides were screened in the training set through orthogonal partial least-squares-discriminant analysis and receiver operating characteristic curve analysis. These six peptides were derived from proteins involved in coagulation and complement activation. We evaluated the diagnostic ability of the six peptides in the testing set through hierarchical cluster analysis, and showed that perturbation of these peptides could distinguish patients with active UC, patients with remitting UC and healthy people. This study validated the feasibility of serum peptidomics for the discovery of diagnostic markers, and provided a potential method for diagnosing different stages of UC.

Development of a fragmentation pattern of synthetic cannabinoids based on electrospray ionization mass spectrometry in positive ion mode to screen synthetic cannabinoids in illicit products

To explore the MS fragmentation pattern of synthetic cannabinoids by electrospray ionization mass spectrometry, twenty-seven synthetic cannabinoids were systematically investigated by liquid chromatography coupled to high-resolution quadrupole Orbitrap mass spectrometry(LC-Q-Orbitrap/MS)with positive mode of electrospray ionization. Based on tandem multistage MS and high resolution MS data, MS fragmentation pattern of synthetic cannabinoids was summarized. The cleavage of CC bonds next to the oxygen at the side chain on the C-3 position of synthetic cannabinoids was the characteristic fragmentation pathway of synthetic cannabinoids in the positive mode of electrospray ionization. When the synthetic cannabinoids with a 3-carbamoylpropyl-indole/indazole structure, NH3, CO, NH2CHO and CH2(CH3)2 were easy to lose to form different ions. While when the synthetic cannabinoids with a 3-carboxamide-indole/indazole structure, the side chain on the C-3 position was susceptible to γ-cleavage. In addition, this MS fragmentation pattern was applied to quickly screen whether electronic cigarette oil and tobacco from drug cases contain synthetic cannabinoids. This kind of compounds had strong fragmentation pattern, which provided new evidence for the rapid structure identification of synthetic cannabinoids.

Profiling fragments for carotenoid esters in Penaeus monodon by ultra-high-performance liquid chromatography/quadrupole-Orbitrap high-resolution mass spectrometry.

The precise identification of carotenoid esters of Penaeus monodon, especially those in the carotenoid skeleton, needs to occur during mass spectrometry analysis. Detailed structural information about carotenoid esters is significant not only for the assessment of nutritional quality, but also for tracing biosynthetic precursors. The profiling of carotenoid esters in P. monodon was elucidated using ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC/Q-Orbitrap-HRMS). The raw LC/MS data were analyzed using Exact Finder™ software. The structurally relevant ions, *l and *m, were considered markers of the astaxanthin monoester. Moreover, the carotenoid skeleton was unequivocally identified using the diagnostic ions *i, *j/*j' and *g/*g' generated by the carbon-carbon bond cleavage between β-ionone ketones and conjugated polyene moieties. In total, 24 carotenoid esters were identified in P. monodon based on the fragmentation patterns discussed above. The identified carotenoid skeleton includes astaxanthin, astacene, oxidized astaxanthin and adonixanthin, which have been described for the first time. Characterization of the unknown carotenoid esters demonstrates the capabilities of this methodology, which is significant for enriching the carotenoid species in P. monodon.

Foodinformatic prediction of the retention time of pesticide residues detected in fruits and vegetables using UHPLC/ESI Q-Orbitrap

The present work describes the development of an in silico model to predict the retention time (tR) of a large Compound DataBase (CDB) of pesticides detected in fruits and vegetables. The model utilizes ultrahigh-performance liquid chromatography electrospray ionization quadrupole-Orbitrap (UHPLC/ESI Q-Orbitrap) mass spectrometry (MS) data. The available CDB was properly curated, and the pesticides were represented by conformation-independent molecular descriptors. In an attempt to improve the model predictions, the best four MLR models obtained were subjected to a consensus analysis. The optimal model was evaluated by means of the coefficient of determination and the residual standard deviation in calibration, validation, and prediction, along other internal and external validation criteria to accomplish the guidelines defined by the Organization for Economic Co-operation and Development. Finally, the in silico model was applied to predict the tR of an external set of 57 pesticides.