Quadrupole Orbitrap Mass Spectrometry Research Articles

Chemical Labeling Assisted Detection and Identification of Short Chain Fatty Acid Esters of Hydroxy Fatty Acid in Rat Colon and Cecum Contents.

Branched fatty acid esters of hydroxy fatty acids (FAHFAs) are novel endogenous lipids with important physiological functions in mammals. We previously identified a new type of FAHFAs, named short-chain fatty acid esterified hydroxy fatty acids (SFAHFAs), with acetyl or propyl esters of hydroxy fatty acids of carbon chains, C ≥ 20. However, sensitive determination of SFAHFAs is still a challenge, due to their high structural similarity and low abundance in biological samples. This study employs one-step chemical derivatization following total lipid extraction using 2-dimethylaminoethylamine (DMED) for enhanced detection of SFAHFAs. The labeled extracts were subjected to ultrahigh performance liquid chromatography coupled to linear ion trap quadrupole-Orbitrap mass spectrometry (UHPLC/LTQ-Orbitrap MS). Our results demonstrated that the detection sensitivities of SFAHFAs increased after DMED labeling, and is highly helpful in discovering six additional novel SFAHFAs in the cecum and colon contents of WKAH/HKmSlc rats fed with normal and high-fat diet (HFD). The identified DMED labeled SFAHFAs were characterized by their detailed MS/MS analysis, and their plausible fragmentation patterns were proposed. The concentrations of SFAHFAs were significantly reduced in the cecum of HFD group compared to the control. Hence, the proposed method could be a promising tool to apply for the enhanced detection of SFAHFAs in various biological matrices, which in turn facilitate the understanding of their sources, and physiological functions of these novel lipids.

Identification of chemical constituents in Qizhi Tongluo Capsules by UPLC-Q-Orbitrap HRMS

Qizhi Tongluo Capsules, which is composed of 26 herbal drugs, is mainly used as the assistant therapy for apoplexy sequelae. The chemical composition of Qizhi Tongluo Capsules was complex,but its chemical constituents and the pharmacodynamic material basis remain unreported. The ultrahigh performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry(UPLC-Q-Orbitrap HRMS) was applied to recognize the chemical constituents of Qizhi Tongluo Capsules. The analysis was performed on a Waters Acquity UHPLC HSS T3 column with acetonitrile-water as the mobile phase for gradient elution. Heated electrospray ionization(HESI) in both positive and negative ion modes was adopted to collect the data. The chemical constituents were identified and confirmed by analyzing the accurate molecular weight, the mass fragmentation pattern, and comparing with the mass data from the reference substances and literature. A total of 119 components were identified, including 22 flavones, 12 saponins, 10 salvianolic acids, 5 butylphthalides, 4 anthraquinones, 4 monoterpenoid glycosides, 2 caffeoyl-quinic acids, 2 coumarins, 2 alkaloids, and 1 stilbene, as well as the common constituents in the herb, such as amino acids and organic acids. The chemical constituents of Qizhi Tongluo Capsules were characterized rapidly for the first time in this study, laying a foundation for the further analysis of active compounds and quality control.

Rapid characterization of Schisandra species by using direct analysis in real time mass spectrometry

Direct analysis in real time ionization source coupled with quadrupole orbitrap mass spectrometry (DART-Q-Orbitrap MS) was applied to analyze the Schisandra chinensis (S. chinensis) and Schisandra sphenanthera (S. sphenanthera) samples. The experimental condition including the ionization gas and gas temperature were optimized to obtain the best performance. The DART-MS analysis was operated using helium at 250 °C. The partial least squares discriminant analysis (PLS-DA) was conducted based on the DART-MS data to explore the differences between S. chinensis and S. sphenanthera samples. The clear separation between groups was observed in the PLS-DA score plot, indicating the chemome diversity of these two samples. Then 8 compounds that contribute most to the sample classification were selected and annotated, and the intensity change tendency of these compounds was similar to that obtained by the high-performance liquid chromatography (HPLC) method. Besides, these two species can also be discriminated by examining the existence of the compound anwulignan at m/z 328.1656 in this study. Our results show that DART-MS is a powerful analytical tool with the merit of rapid analysis speed, easy to handle, low consumption of organic solvent, and has the great potential for rapid detection and discrimination of S. chinensis and S. sphenanthera. It is expected that the established method could provide a rapid, reliable method for the quality assessment of Schisandra species, and expand this method to the analysis of other herbal medicines.

Heart-cutting two-dimensional liquid chromatography coupled to quadrupole-orbitrap high resolution mass spectrometry for determination of N,N-dimethyltryptamine in rat plasma and brain; Method development and application

The orthogonal heart-cutting liquid chromatography (LC) modes coupled to high-resolution tandem mass spectrometry (HRMS/MS) provide a number of possibilities to enhance selectivity and sensitivity for the determination of targeted compounds in complex biological matricies. Here we report the development of a new fast 2D-LC-(HRMS/MS) method and its successful application for quantitative determination of the level of plasma and brain N,N-dimethyltriptamine (DMT) using α-methyltryptamine (AMT) as internal standard in an experimental model of cerebral ischemia/reperfusion using DMT administration. The 2D-LC separation was carried out by a combination of hydrophilic interaction liquid chromatography (HILIC) in the first dimension followed by second-dimensional reversed-phase (RP) chromatography within a total run time of 10 min. The enrichment of HILIC effluent of interest containing DMT was performed using a C18 trapping column. During method development several parameters of sample preparation procedures, chromatographic separation and mass spectrometric detection were optimised to achieve high DMT recovery (plasma: 90 %, brain: 88 %) and sensitivity (plasma: 0.108 ng/mL of LOD, brain: 0.212 ng/g of LOD) applying targeted analytical method with strict LC and HRMSMS confirmatory criteria.Concerning rat plasma sample, the concentration of DMT before hypoxia (49.3–114.3 ng/mL plasma) was generally higher than that after hypoxia (10.6–96.1 ng/mL plasma). After treatment, the concentration of DMT in brain was elevated up to the range of 2–6.1 ng/g.Overall, our analytical approach is suitable to detect and confirm the presence of DMT administered to experimental animals with therapeutic purpose in a reliable manner.

Identification of the Metabolites in Rat Urine after Oral Administration and Elucidation of the Metabolic Process of Naozhenning Granule Using LC-MS.

Naozhenning (NZN) granule, a Chinese herbal formula, is widely used to treat craniocerebral trauma and promote functional recovery. In our previous study, the chemical components, as well as the serum metabolites in the male Sprague-Dawley rats of the NZN granule after oral administration were characterized. In this study, the urine metabolites in the male Sprague-Dawley rats were further investigated by ultrahigh-performance liquid chromatography-Q Exactive hybrid quadrupole-Orbitrap high-resolution accurate mass spectrometry. In order to identify the urine metabolites comprehensively, three sample preparation methods were used, including solid-phase extraction, protein precipitation method and solvent partition. Based on the accurate molecular weight and the fragmentation information from the MS spectra, a total of 76 urine metabolites were identified, which including 17 prototypes and 59 metabolites. The results showed that the detected urine metabolites were different for the different pretreatment methods, as some metabolites could only be detected in the particular pretreatment method. In addition, the metabolic processes of the components from NZN granule to the serum and urine were also elucidated and discussed. The results will provide useful information for further studying the relationship between the chemical components and pharmacological activity of NZN granule.

Reciprocal Interactions between Epigallocatechin-3-gallate (EGCG) and Human Gut Microbiota In Vitro.

Interaction of tea phenolics with gut microbiota may play an integral role in the health benefits of these bioactive compounds, yet this interaction is not fully understood. Here, the metabolic fate of epigallocatechin-3-gallate (EGCG) and its impact on gut microbiota were integrally investigated viain vitro fermentation. As revealed by ultrahigh performance liquid chromatography hybrid quadrupole Orbitrap mass spectrometry (UHPLC-Q-Orbitrap-MS), EGCG was promptly degraded into a series of metabolites, including 4-phenylbutyric acid, 3-(3′,4′-dihydroxyphenyl)propionic acid, and 3-(4′-hydroxyphenyl)propionic acid, through consecutive ester hydrolysis, C-ring opening, A-ring fission, dehydroxylation, and aliphatic chain shortening. Microbiome profiling indicated that, compared to the blank, EGCG treatment resulted in stimulation of the beneficial bacteria Bacteroides, Christensenellaceae, and Bifidobacterium. Additionally, the pathogenic bacteria Fusobacterium varium, Bilophila, and Enterobacteriaceae were inhibited. Furthermore, changes in concentrations of metabolites, including 4-phenylbutyric acid and phenylacetic acid, were strongly correlated with changes in the abundance of specific gut microbiota. These reciprocal interactions between EGCG and gut microbiota may collectively contribute to the health benefits of EGCG.

Simultaneous separation and determination of 32 fentanyl-related substances, including seven sets of isomeric fentanyl analogues, by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry.

A method for separation and determination of 32 fentanyl-related substances, including seven sets of isomeric fentanyl analogues, was developed using ultra-high-performance liquid chromatography coupled with quadrupole-orbitrap high-resolution mass spectrometry. The collision energy, chromatographic column, and mobile phase were optimized. All compounds were efficiently flushed out of a universal C18 column with a soft gradient consisting of solvent A (2mM ammonium formate and 0.1% formic acid in water) and solvent B (2mM ammonium formate and 0.1% formic acid in methanol) in only 20 min, achieving excellent resolution. Detection and analysis were carried out simultaneously in the positive ion mode using the full scan and data-dependent tandem mass spectrometry modes with a normalized collision energy of 40. The method was validated in terms of limit of detection, limit of quantification, linearity, accuracy, and precision. For all fentanyl-related substances, the limit of detection (0.5ng/mL) and limit of quantification (1ng/mL) were adequate for screening and quantification in daily drug control. Calibration curves for all compounds were established in the range of 1-500ng/mL. The intra- and interday precision (RSD%) were within 0.4-2.3 and 0.7-2.7%, respectively. The accuracy ranged from 99 to 106%. The method was applied to analyze seized drug samples.

Practical approach to develop a multi-group screening method for detection of mycotoxins, pesticides and veterinary drugs in food.

A multi-group screening method to detect residues of veterinary drugs in meat and environmental contaminants in wheat flour has been developed using liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (LC-HRMS). The procedure was tested for over 300 representative compounds (173 veterinary drugs, 122 pesticides and 9 mycotoxins) analysing in parallel negative and positive (spiked) samples according to European validation rules. The Screening Target Concentrations (STCs) were chosen conservatively with respect to the method purposes. Interpretation of results was based on retention time, mass accuracy of precursor and MS2 spectral library. Evaluating the percentage of false negative results, 280 out of the 304 analytes were detectable at the STCs (false compliant rate ≤ 5%). In wheat flours, incurred levels of mycotoxins, deoxynivalenol and 3-acetyldeoxynivalenol, higher than STCs, were frequently found, whereas in meat, the most detected veterinary drugs were antibiotics generally at negligible concentrations (<10 μg kg-1 ). Finally, seven test materials from proficiency test schemes were successfully tested.

Identification of short-chain fatty acid esters of hydroxy fatty acids (SFAHFAs) in a murine model by nontargeted analysis using ultra-high-performance liquid chromatography/linear ion trap quadrupole-Orbitrap mass spectrometry.

Fatty acid esters of hydroxy fatty acids (FAHFAs) are recently discovered endogenous lipids with outstanding health benefits. FAHFAs are known to exhibit antioxidant, antidiabetic and anti-inflammatory properties. The number of known long-chain FAHFAs in mammalian tissues and dietary resources increased recently because of the latest developments in high-resolution tandem mass spectrometry techniques. However, there are no reports on the identification of short-chain fatty acid esterified hydroxy fatty acids (SFAHFAs). Intestinal contents, tissues, and plasma of rats fed with high-fat diet (HFD) and normal diet (ND) were analyzed for fatty acids, hydroxy fatty acids, and FAHFAs using ultra-high-performance liquid chromatography (UHPLC) and linear trap quadrupole-Orbitrap mass spectrometry (LTQ Orbitrap MS) with negative heated electrospray ionization. Untargeted analysis of total lipid extracts from murine samples (male 13-week-old WKAH/HKmSlc rats) led to the identification of several new SFAHFAs of acetic acid or propanoic acid esterified long-chain (>C20)-hydroxy fatty acids. Furthermore, MS3 analysis revealed the position of the hydroxyl group in the long-chain fatty acid as C-2. The relative amounts of SFAHFAs were quantified in intestinal contents and their tissues (Cecum, small intestine, and large intestine), liver, and plasma of rats fed with HFD and ND. The large intestine showed the highest abundance of SFAHFAs with a concentration range from 0.84 to 57 pmol/mg followed by the cecum with a range of 0.66 to 28.6 pmol/mg. The SFAHFAs were significantly altered between the HFD and ND groups, with a strong decreasing tendency under HFD conditions. Identification of these novel SFAHFAs can contribute to a better understanding of the chemical and biological properties of individual SFAHFAs and their possible sources in the gut, which in turn helps us tackle the role of these lipids in various metabolic diseases.

Identification of suberosin metabolites in human liver microsomes by high-performance liquid chromatography combined with high-resolution quadrupole-orbitrap mass spectrometer.

Suberosin is a natural prenylated coumarin derivative isolated from Citropsis articulata. It has various pharmacological properties, especially as an anticoagulant, for which it has been used since antiquity. However, its metabolic pathway and metabolites have not yet been studied. Therefore, this study characterizes its metabolic pathway and metabolites in human liver microsomes (HLMs) using high-resolution quadrupole-orbitrap mass spectrometry (HRMS/MS). Eight metabolites (M1-M8) were found, including three monohydroxylated (M1-M3), one hydrated (M4), three dihydroxylated (M5-M7), and one glucuronide conjugate (M8). Furthermore, forms of cytochrome P450 (CYPs) responsible for suberosin metabolism in HLMs were characterized. CYP1A2 was identified as a major enzyme for the production of M1 and M5 metabolites. The M2, M3, and M7 metabolites were predominantly generated by CYP2B6. M8 was the only phase II metabolite, identified as a glucuronide conjugate from either M1 or M2. This glucuronide conjugate may be the only promising metabolite from phase II metabolism. Phase I metabolism, especially hydroxylation, was found to provide a predominant metabolic pathway of suberosin in HLMs. Further studies should be conducted to explore the metabolites, examining their efficacy and their toxicity in an in vivo system.

A strategy for the determination of flavor substances in goat milk by liquid chromatography-high resolution mass spectrometry

A new analytical method for untargeted screening of flavor compounds in goat milk and milk flavor using mass spectrometry was developed and validated. All compounds of low molecular weight were considered as candidate chemicals, instead of focusing only on compounds that already have a known affect on the flavor quality of goat milk. High performance liquid chromatography coupled with high resolution quadrupole orbitrap mass spectrometry based on external standard was used to analyse flavor compounds in complex samples. The untargeted screening strategy is data pre-processing, automated componentization, suspect library spectra searching and the retained analytes confirming based on the reference standard solutions. Forty-two flavor compounds were confirmed and analyzed. The established method was validated by considering the guidelines specified in Commission Decision 2002/657/EC and European SANCO/12571/2013 Guideline 2013. This validated method was successfully applied to samples detection, and some unique flavor compounds were found between goat milk and milk flavor samples, which can provide some useful references for the illicit addition of flavors and fragrances in dairy products.

Quantitative analysis of bioactive components in walnut leaves by UHPLC-Q-Orbitrap HRMS combined with QAMS

Walnut leaves are rich in phenolic components with antibiotic and antioxidative effects. However, few studies have reported the quantitative analysis of active components in walnut leaf. In this study, a novel method for quantifying the active components in walnut leaves was developed by combining ultra-high performance liquid chromatography-hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) with quantitative analysis of multi-components by a single marker (QAMS). In total, 13 bioactive components were analyzed by a single marker, quercetin. To evaluate the accuracy of this method, an auxiliary quantification method with 13 reference standards was established and validated. The standard method differences (SMDs) of the quantification results between QAMS and the auxiliary method were lower than 20%, indicating that the QAMS method can accurately determine the active components in walnut leaves. This method can provide a reference to address the absence of reference standards for analyzing other foods and herbs.

Extensive screening of cyclopeptide toxins in mushrooms by ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry

A non-target screening method of cyclopeptide toxins and their analogues in mushroom was developed, using ultra-high-performance liquid chromatography coupled with quadrupole Orbitrap mass spectrometry (UHPLC-Q-Orbitrap MS) followed by mass spectrometry databases retrieval and software tools analysis for the candidate analogues. Three cyclopeptide toxins in the toxic mushroom Amanita rimosa were firstly screened without standard, and two of them were unknown analogues which were tentatively identified by the accurate masses, isotopic patterns and characteristic fragments. A validated quantitative method was performed to rapidly quantify three major cyclopeptide toxins in the Amanita rimosa sample including α-manitin, β-amanitin and phalloidin, and their contents were detected to be 4.52 mg/kg, 2.37 mg/kg and 2.53 mg/kg, respectively. The developed method has good selectivity and sensitivity for rapid and comprehensive screening the cyclopeptide toxins and their analogues in mushrooms at trace levels. Successful non-target screening of trace cyclopeptide toxin analogues will guarantee the food safety in mushrooms consumption.

Chemical composition analysis of pomegranate seeds based on ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry

Pomegranate fruit has shown a variety of pharmacological effects, however, the bioactive constituents in pomegranate seeds have not been fully identified. To this end, the chemical compositions of pomegranate seeds were analyzed using ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS). Prior to analysis, pomegranate seed samples were treated by ultrasonic/microwave-assisted extraction (UMAE). A total of 88 chemical compounds were tentatively identified based on accurate-mass measurements for precursor and fragment ions, including flavonoids, coumarins, phenolic acids, amino acids, and nucleosides. Their mass spectrometric fragmentation pathways were investigated. The study has revealed the nutritional value of pomegranate seeds, paving the way for future further applications of pomegranate seeds in nutrition and health care industry.

Rapid identification of chemical compositions in callicarpa kwangtungensis Chun by ultra-high-performance liquid chromatography with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry.

Callicarpa kwangtungensis Chun is a traditional Chinese medicine that has various therapeutic effects. Despite its wide use in Chinese medicine, the study is still quite limited, especially its chemical compositions. In this research, an ultra-high-pressure liquid chromatography coupled with Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry tandem mass spectrometry method was utilized to analyze its chemical compositions for the first time. As a result, a total of 124 compounds, including 20 phenylethanoid glycosides, 31 flavonoids, 36 organic acids, 26 terpenoids and 11 phenols, were identified or tentatively characterized in 30min. Among them, 49 compounds, including 5 phenylethanoid glycosides, 12 flavonoids, 16 organic acids, 12 terpenoids, and 4 phenols, were identified in Callicarpa kwangtungensis Chun for the first time. Besides, the fragmentation pathways were also discussed. This research established a rapid and reliable method to analyze the chemical compositions of complicated herb without the process of isolation, and provide abundant information on the chemical material basis for further bioactivity and quality control studies.

Integrated biomarker for type 2 diabetes mellitus and impaired fasting glucose based on metabolomics analysis using ultra-high performance liquid chromatography quadrupole-Orbitrap high-resolution accurate mass spectrometry.

The prevalence of type 2 diabetes mellitus (T2DM) is increasing but its early diagnosis in high risk populations remains challenging using only fasting blood glucose (FBG) or hemoglobin A1c measurements. It is, therefore, important to search for an integrated biomarker for early diagnosis by determining metabolites associated with the progression of the disease. We recruited 149 participants (51 T2DM patients, 50 individuals with impaired fasting glucose (IFG) and 48 normal glucose tolerance subjects). Their serum samples were analyzed based on a metabolomics approach using ultra-high-performance liquid chromatography quadrupole-Orbitrap high-resolution accurate mass spectrometry (UHPLC/Q-Orbitrap HRMS). The changes in metabolites were profiled and evaluated using univariate and multivariate analyses. Furthermore, a biomarker model was established and the potential biomarkers were evaluated using binary logistic regression analysis and receiver operating characteristic analysis with AUC (area under the curve). Pathway analysis of differential metabolites was performed to reveal the important biological information. Thirty-eight differential metabolites were identified as significantly associated with T2DM patients and 23 differential metabolites with IFG individuals, mainly amino acids, carnitines, and phospholipids. By evaluating 17 potential biomarkers, we defined a novel integrated biomarker consisting of 2-acetolactate, 2-hydroxy-2,4-pentadienoate, L-arabinose and L-glutamine. The AUCs of the integrated biomarker with IFG and T2DM patients were 0.874 and 0.994, respectively, which showed a superior diagnostic performance. The levels of 2-acetolactate and 2-hydroxy-2,4-pentadienoate were strongly positively correlated with FBG, while L-glutamine and L-arabinose were strongly negatively associated with FBG. After pathway analysis, it was suggested that the majority of the influenced metabolic pathways associated with diabetes referred to amino acid metabolism. The integrated biomarker could diagnose IFG and T2DM with a superior diagnostic performance. This finding provides support for novel biomarkers in the diagnosis and treatment of diabetes.

Effects of spices on the formation of biogenic amines during the fermentation of dry fermented mutton sausage

A precise and unambiguous quantitative strategy for six biogenic amines in dry fermented mutton sausage with liquid chromatography tandem quadrupole Orbitrap mass spectrometry was developed to investigate the inhibitory effects of star anise, amomum tsao-ko, clove, cassia, fennel, bay leaf, and nutmeg on the accumulation of biogenic amines. Compared the data-dependent MS2 fragmentation (dd-MS2), variable data-independent acquisition (vDIA), and multiplex data-independent acquisition (mDIA), and the mDIA acquisition mode was selected for further analysis. The LODs and LOQs were 0.9–1.5 μg kg−1 and 2.9–5.0 μg kg−1. The maximum inhibition of spice on tryptamine, putrescine, spermidine, 2-phenylethylamine, tyrosamine, and histamine were 21.8%, 19.3%, 27.5%, 24.6%, 18.7% and 24.4%, which revealed that the accumulation of BAs was significantly inhibited by spice extracts, while cassia and fennel extracts showed the best effect. Thus, the established method can provide a better reference for dry fermented mutton sausage quality, safety and trade analysis.

Comprehensive analysis of oat avenanthramides using hybrid quadrupole-Orbitrap mass spectrometry: Possible detection of new compounds.

Avenanthramides (AVNs) are constituents unique to oats and have many outstanding health benefits. AVNs are antioxidants and possess anti-inflammatory, antifungal and antibacterial activity. The number of known AVNs increased recently because of the latest developments in high-resolution tandem mass spectrometry (HRMS/MS) techniques. Oat seed extract from 10 oat cultivars was analysed using ultra-high-performance liquid chromatography (UHPLC) and Q Exactive hybrid quadrupole-Orbitrap mass spectrometry (HRMS/MS) with positive heated electrospray ionization. Thirty-five AVNs were identified and characterized in seed extracts, and the structures of 10 novel AVNs were tentatively elucidated, among which were AVNs bearing a cinamoyl or sinapoyl moiety. These AVNs are reported in oats for the first time. The method was validated using AVN standards (AVNs 2c, 2f and 2p), with limits of detection and quantitation at low picomole levels. Recovery of AVN standards varied from 83% to 106%, and relative standard deviations ranged from 2% to 9%. The total AVNs in the selected oat varieties ranged from 36.0 to 302.5 μg/g (dry weight), with AVN 2c, AVN 2f and AVN 2p representing approximately 65%-70% of that total. Our comprehensive method for detecting the full avenanthramide spectrum can contribute to better understanding the chemical and biological properties of individual AVNs for utilization in developing new oat cultivars and novel functional foods.

A comprehensive study of lipid profiles of round scad (Decapterus maruadsi) based on lipidomic with UPLC-Q-Exactive Orbitrap-MS

Round scad (Decapterus maruadsi) is rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, there is no comprehensive information covering its lipidomic profile. In this study, lipid profiles including fatty acid composition, distribution and detailed structure information were explored using gas chromatography-flame ionization detector (GC-FID) and ultra-high-performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry (UPLC-Q-Exactive Orbitrap-MS). The results showed that triacylglycerol (TG) was the dominant class, and the EPA and DHA were concentrated as glycerophospholipid (GP). The saturated fatty acids and monounsaturated fatty acids were mainly esterified in positions 1 and 3 of TG and sn-1-position of GP, while the polyunsaturated fatty acids (PUFA) were mainly esterified in sn-2-position of TG and GP. A total of 1282 species from six classes (21 subclasses) including glycerolipids (GL), sphingolipids (SP), GP, fatty acyls (FA), saccharolipids (SL) and prenol lipids (PR) were identified. Several molecular species were characterized with PUFA, especially EPA and DHA in GP. Considering the superior fatty acids composition and distribution of round scad, it is deserved for further exploitation of its marine lipid source on account of the healthy and nutritional functions.

Simultaneous Determination of Pesticides and Veterinary Pharmaceuticals in Environmental Water Samples by UHPLC–Quadrupole-Orbitrap HRMS Combined with On-Line Solid-Phase Extraction

Pesticides and veterinary pharmaceuticals are used for effective crop production and prevention of livestock diseases; these chemicals are released into the environment via various pathways. Although the chemicals are typically present in trace amounts post-release, they could disturb aquatic ecosystems and public health through resistance development toward drugs or diseases, e.g., reproductive disorders. Thus, the residues of pesticides and veterinary pharmaceuticals in the environment must be managed and monitored. To that end, we developed a simultaneous analysis method for 41 target chemicals in environmental water samples using ultra-high-performance liquid chromatography (UHPLC)–quadrupole-orbitrap high-resolution mass spectrometry (HRMS) coupled with an on-line solid-phase extraction system. Calibration curves for determining linearity were constructed for 10–750 ng∙L−1, and the coefficient of determination for each chemical exceeded 0.99. The method’s detection and quantitation limits were 0.32–1.72 ng∙L−1 and 1.02–5.47 ng∙L−1, respectively. The on-line solid-phase extraction system exhibited excellent method reproducibility and reduced experimental error. As the proposed method is applicable to the monitoring of pesticides and veterinary pharmaceuticals in surface water and groundwater samples acquired near agricultural areas, it allows for the management of chemicals released into the environment.