Quadrupole Tandem Mass Spectrometry Research Articles

Metabolic fingerprinting strategy: Investigation of markers for the detection of extra virgin olive oil adulteration with soft-deodorized olive oils

As extra virgin olive oil (EVOO) is a high value commodity, it might be subject of various fraudulent practices. This study is focused on a challenging authentication issue, addition of lower grade, soft-deodorized olive oil to EVOO. In the first step, sample sets of authentic EVOOs, soft-deodorized oils and their admixtures were extracted by aqueous methanol; obtained polar fractions were then analysed by ultra-high performance liquid chromatography coupled to hybrid quadrupole time-of-flight high-resolution tandem mass spectrometry (UHPLC-QTOF-HRMS/MS). Subsequent chemometric evaluation of metabolic fingerprints enabled suggestion of several ions that might be characteristic for deodorized oils; most of tentatively identified compounds were oxidized fatty acid derivatives. In the second phase, the ‘marker' ions were employed for target analysis by ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS) what enabled achieving lower the detection limits. Two compounds were selected as the best markers for detection of soft-deodorized olive oil addition, tentatively identified as methyl ester of hydroxy octadecenoic acid and ester derivative of oleic acid. • Addition of soft-deodorized olive oil into extra virgin olive oil was studied. • Untargeted approach revealed new markers emerging in soft-deodorization process. • Markers were successfully tested by target approach to be used in routine practice. • Best markers were tentatively identified as fatty acid esters.

Simultaneous Determination of Multi-Class Pesticide Residues and PAHs in Plant Material and Soil Samples Using the Optimized QuEChERS Method and Tandem Mass Spectrometry Analysis.

New analytical approaches to the simultaneous identification and quantification of 94 pesticides and 13 polycyclic aromatic hydrocarbons (PAHs) in five representative matrices (pepper, apple, lettuce, wheat, and soil) were developed. The analyses were based on gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-MS/MS). The procedure was optimized by changing the solvent used during the extraction, from acetonitrile to the acetone: n-hexane mixture at a volume ratio of 1:4 (v/v), as well as the use of a reduced amount of water during the extraction of compounds from cereals. An additional modification was the use of florisil instead of GCB in the sample cleanup step. A full method validation study was performed, at two concentration levels (LOQ and 1000 × LOQ), which showed satisfactory results for all analytes from the PAHs group, with recoveries ranging from 70.7–115.1%, and an average RSD of 3.9%. Linearity was tested in the range of 0.001–1.000 mg/kg and showed coefficients of determination (R2) ≥ 0.99 for all PAHs. Satisfactory recovery and precision parameters (LOQ and 100 × LOQ) were achieved for almost all analytes from the pesticide group in the range of 70.1–119.3% with the mean RSD equal to 5.9%. The observed linearity for all analytes in the concentration range of 0.005–1.44 mg/kg was R2 ≥ 0.99, with the exception of famoxadone, chizalofop-p-ethyl, prothioconazole, spirodiclofen, tefluthrin, and zoxamid. The extended uncertainties were estimated, using a top-down approach of 9.9% (average) and 15.3% (average) for PAHs and pesticides samples, respectively (the coverage factor k = 2, the 95% confidence level). Ultimately, the method was successfully applied to determine pesticide residues in commercial samples of fruit, vegetables and grain, and soil samples for PAHs, which were collected from selected places in the Podkarpacie region. A total of 38 real samples were tested, in which 10 pesticides and 13 PAHs were determined. Proposed changes allow us to shorten the sample preparation time (by 20%) and to reduce the consumption of organic solvents (by 17%). The use of florisil for sample cleanup, instead of GCB, improves the recovery of compounds with flat particles.

Simultaneous Determination of Levamisole, Mebendazole, and the Two Metabolite Residues of Mebendazole in Poultry Eggs by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

The quantitative determination of levamisole (LMS), mebendazole (MBZ), and the two metabolites of MBZ, 5-hydroxymebendazole (HMBZ) and 2-amino-5-benzoylbenzimidazole (AMBZ), in poultry eggs (hen, duck, and goose) was achieved with high-performance liquid chromatography–tandem triple quadrupole mass spectrometry (HPLC–MS/MS). Samples were pretreated by liquid–liquid extraction and solid-phase extraction (LLE–SPE) to extract the target compounds, and an Oasis MCX SPE column was used for purification. Determination was performed on an Xbridge C18 column with 0.1% formic acid aqueous solution and acetonitrile as mobile phases. LMS, MBZ, HMBZ, and AMBZ were detected in a triple-quadrupole mass spectrometer with ESI in positive mode and quantified with an external standard. In blank eggs, the target analyte concentrations were within the limits of quantification (LOQs)—25 μg/kg (LMS) and 150 μg/kg (MBZ, HMBZ, and AMBZ)—and the matrix-matched calibration curves had good linearity (R2 ≥ 0.9990). In the same concentration range, the average recoveries of the target analytes were 85.98–97.38% (n = 6); the relative standard deviation (RSD), intraday RSD, and interday RSD ranged from 2.06 to 4.22%, 1.40 to 5.85%, and 2.34 to 6.32%, respectively. The limits of detection (LODs) ranged from 0.03 to 0.33 µg/kg, and the LOQs ranged from 0.08 to 1.00 µg/kg. Experimental verification showed that the HPLC–MS/MS method exhibited high specificity and sensitivity for quantitative analyses of egg samples. This study provides a rapid, efficient, and sensitive method for the simultaneous detection of LMS, MBZ, HMBZ, and AMBZ residues in foods of animal origin.

Determination of creatinine and 2-thiothiazolidine-4-carboxylic acid in urine by ultra high performance liquid chromatography tandem mass spectrometry

Objective: To establish an ultrahigh performance liquid chromatography tandem mass spectrometry method for the determination of creatinine (Cre) and 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. Methods: In October 2020, the end-of-shift urine samples of the monitored subjects were taken, and the filtrate was prepared by centrifugation. After separated by ultra high performance liquid chromatography C18 column, acetonitrile and 0.2% acetic acid aqueous solution were used as mobile phases for gradient elution, the three quadrupole tandem mass spectrometry adopted an electrospray ion source (ESI) , the ion source temperature was 500 ℃ , and the air curtain gas flow rate was 31.4 L/min, qualitative and quantitative analysis of Cre and TTCA were carried out under the multiple reaction monitoring mode. Results: The linear range of Cre was 1.0-1 000.0 μg/L, the linear equation was y=947.3x-1605.6, and the correlation coefficient was 0.9994. The detection limit and the limit of quantitation were 0.3, 1.0 μg/L. When the addition concentrations were 50.0, 150.0 and 450.0 μg/L, the recovery rates were 92.8%-94.6% , the intra assay precisions were 3.6%-5.7% , and the inter assay precisions were 3.4%-5.4%. The linear range of TTCA was 0.1-200.0 μg/L, the linear equation was y=1164.7x-2243.9, and the correlation coefficient was 0.9991. The detection limit and the limit of quantitation were 0.03, 0.1 μg/L. When the addition concentrations were 10.0, 40.0 and 160.0 μg/L, the recovery rates were 90.8%-93.6%, the intra assay precisions were 4.6%-7.4%, and the inter assay precisions were 4.4%-6.9%. Conclusion: The sample pretreatment process of the ultra high performance liquid chromatography tandem mass spectrometry method for the determination of Cre and TTCA in urine is simple, and the continuous determination of Cre and TTCA in urine can be realized only by switching mass spectrometry parameters under the same chromatographic conditions, which is accurate and efficient, and each performance index of the method meets the determination requirements.

Stability of a calibrant as certified reference material for determination of trans-zearalenone by high performance liquid chromatography-diode array detection-triple quadrupole tandem mass spectrometry.

In this study, a trans-zearalenone (trans-ZEN) calibrant in acetonitrile as certified reference material (CRM) was prepared and intensively investigated the stability by high performance liquid chromatography coupled diode array detection and triple quadrupole tandem mass spectrometry (HPLC-DAD-MS/MS). The photoisomerization and degradation of main component and related impurities in trans-ZEN calibrant CRM was studied in detail under different light conditions such as UV light (254nm), sunlight, and visible light. Trans-ZEN in acetonitrile was confirmed a significant shift toward cis-ZEN up to a 52% cis-isomerization rate after exposing to UV light (254nm) in transparent ampule for 1day. The unsaturated double bond photosensitive groups of trans-ZEN and cis-ZEN will further undergo photoreaction to generate more isomers and related products with the increase of UV irradiation time. The calibrant in amber ampules was relatively stable after exposing to sunlight for 28days, with only 0.35% cis-isomer observed. The results indicated that trans-ZEN solution calibrant should be packed in amber ampules to avoid UV rays. Thermal stability test exhibited this calibrant was stable over 6weeks even at 60°C. Trans-ZEN was found to be more stable in acetonitrile than in methanol since an unknown impurity was observed in methanol after 6weeks placed at 25°C. The stability study of trans-ZEN calibrant provided a basis for the usage, storage, and transportation of the CRM. A concentration and expanded uncertainty of the trans-ZEN calibrant CRM of 11.01 ± 0.18µg/mL was developed.

Simultaneous determination of the four key fluoroquinolones and two antipsychotics in fish and shrimp by LC-MS/MS

In this study, we developed and validated a liquid chromatography triple quadrupole tandem mass spectrometry (LC-MS/MS) method used to simultaneously determine levels of four fluoroquinolones (ofloxacin, norfloxacin, lomefloxacin, and pefloxacin) and two antipsychotics (diazepam and methaqualone) in fish and shrimp. The samples were extracted with a mixture of anhydrous sodium sulfate and acetonitrile, and purified by C18 cartridge solid-phase extraction with an optimized eluent. The MS2 method was applied to recognize the molecular structure of these compounds according to a main fragmentation scheme. The key ions of identification and quantification were deduced from chemical structures. Multiple reaction monitoring was used to quantitatively analyse the compounds of interest. Satisfactory linearities were obtained (R 2 ≥0.99) with the limits of quantitation (LOQs) ranging between 0.03 and 1.96 μg kg−1. The recoveries were 74–122%, with a relative standard deviation (RSD) below 4.9% for these compounds at the spiking level of three, five, and ten times the LODs, respectively. The LC-MS/MS method allows precise and sensitive determination of residues of six important banned veterinary drugs in fish and shrimp tissue. This methodological approach solved the problem imposed by the need for two or more analysis methods to analyse the compounds of interest described in this study.

A facile molecularly imprinted column coupled to GC-MS/MS for sensitive and selective determination of polycyclic aromatic hydrocarbons and study on their migration in takeaway meal boxes

The analysis of toxic and harmful substances in food has attracted significant attention. In this work, a molecularly imprinted column coupled to gas chromatography-triple quadrupole tandem mass spectrometry method (MIC-GC-MS/MS) method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in takeaway meal boxes was established by comparing the extraction results of 16 PAHs with 5 different sample pretreatment techniques, and the effects of food types and storage conditions on the migration of PAHs was studied by migration test. The conditions of extraction and chromatography-mass spectrometry were optimized. The results showed that the linear ranges were in the wide range of 1–100 ng mL−1 for 16 PAHs, with the correlation coefficients (R) higher than 0.9983; the detection limits (LODs) and the limits of quantification (LOQs) were in the range of 0.08–0.42 μg kg−1 and 0.24–1.26 μg kg −1, respectively; the spiked recoveries at three levels of 10, 20, 30 μg kg−1 were in the range of 86.2%–107.7% with the relative standard deviation (RSD) less than 7.8%. Therefore, this method had high sensitivity and good reproducibility and was suitable for the determination of 16 PAHs in food contact materials. The migration test of PAHs showed that the migration amount of PAHs in takeaway meal boxes was closely related to food types, and the migration amount was positively correlated with contact temperature and contact time in a certain range.

Antibacterial Activity of Chinese Red Propolis against Staphylococcus aureus and MRSA.

The antibacterial activity of propolis has long been of great interest, and the chemical composition of propolis is directly dependent on its source. We recently obtained a type of propolis from China with a red color. Firstly, the antibacterial properties of this unusual propolis were determined against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). Studies on its composition identified and quantified 14 main polyphenols of Chinese red propolis extracts (RPE); quantification was carried out using liquid chromatography triple quadrupole tandem mass spectrometry (LC-QQQ-MS/MS) and RPE was found to be rich in pinobanksin, pinobanksin-3-acetate, and chrysin. In vitro investigations of its antibacterial activity revealed that its activity against S. aureus and MRSA is due to disruption of the cell wall and cell membrane, which then inhibits bacterial growth. Despite its similar antibacterial activities against S. aureus and MRSA, metabolomic analysis further revealed the effects of RPE on bacteria metabolism were different. The untargeted metabolomic results showed that a total of 7 metabolites in 12 metabolic pathways had significant changes (Fold change > 2, p < 0.05 *) after RPE treatment in S. aureus, while 11 metabolites in 9 metabolic pathways had significant changes (Fold change > 2, p < 0.05 *) after RPE treated on MRSA. Furthermore, RPE downregulated several specific genes related to bacterial biofilm formation, autolysis, cell wall synthesis, and bacterial virulence in MRSA. In conclusion, the data obtained indicate that RPE may be a promising therapeutic agent against S. aureus and MRSA.

Integrated LC-MS and GC-MS-Based Metabolomics Reveal the Effects of Plant Competition on the Rye Metabolome.

Plants compete with their neighbors about the limited resources available to them. Plants under induced stress resulting from competition may alter their metabolome to increase their resilience or enhance their defense mechanisms. In the present study, rye (Secale cereale) plants were cocultivated with different densities (3, 12, and 18 plants per pot) of Austrian pea (Pisum sativum subsp. arvense), hairy vetch (Vicia villosa), and Alexandrian clover (Trifolium alexandrinum L.) to elucidate the changes in the rye metabolome in response to the different levels of competition. Global metabolic profiling by liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS), liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS), and gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) was performed on rye plants, and the acquired data were analyzed using uni- and multivariate statistics. Targeted analysis showed that a high level of competition reduced the concentration of aglycone benzoxazinoids (BXs) and increased glycoside BXs in rye roots. Untargeted metabolomics analysis indicated an increase in the rye root content of the allelopathic compounds 4-hydroxybenzoic acid and uracil in response to competition. Untargeted analysis of rye shoots revealed that the plant competition increased the d-pyroglutamic acid, which is an elicitor of reactive oxygen species (ROS). Our results have enhanced the knowledge of the biochemical response of plant species to cocultivation.

Simultaneous Determination of Vitamin D and Its Hydroxylated and Esterified Metabolites by Ultrahigh-Performance Supercritical Fluid Chromatography–Tandem Mass Spectrometry

In this study, an analytical method has been developed that, for the first time, allows simultaneous determination of vitamin D2 and vitamin D3 along with their hydroxylated and esterified forms. A group of 12 vitamin D analogues including vitamin D2 and vitamin D3, seven hydroxylated metabolites, and three ester forms were separated in a single 8.0 min run using ultrahigh-performance supercritical fluid chromatography coupled with triple quadrupole tandem mass spectrometry. Electrospray ionization and atmospheric pressure chemical ionization were investigated as ion sources, of which the latter showed a higher ionization efficiency. Chromatographic conditions were thoroughly evaluated by a step-by-step method, whereas an experimental design was applied for the optimization of the ionization parameters. Calibration and repeatability studies were carried out to validate the instrumental methodology showing determination coefficients higher than 0.9992 and good intra- and interday precision with relative standard deviations for areas and retention times lower than 10 and 2.1%, respectively, for all target analytes. Limits of quantification were below 3.03 μg/L for all compounds. The methodology was then validated and applied for the evaluation of human plasma samples in order to demonstrate its applicability to the analysis of vitamin D analogues in biological samples. Samples of five individuals were analyzed. Results show that linoleate-D3, vitamin D2, vitamin D3, 25-hydroxyvitamin D2, 24,25-dihydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 could be detected in most samples, while the two latter also were quantified in all analyzed samples.

Plasma 25-hydroxyvitamin D3 concentrations and incident risk of ischemic stroke in rural Chinese adults: New insight on ceiling effect

ObjectiveThe aim of this study was to investigate the relationship between 25-hydroxyvitamin D3 (25[OH]D3) and ischemic stroke and its potential modifying factors in rural Chinese adults. MethodsThis nested case-control study was drawn from the H-type Hypertension and Stroke Prevention and Control Project, a community-based, prospective, observational study. Plasma 25(OH)D3 was measured by liquid chromatography with tandem quadrupole mass spectrometry. All stroke records came from the Chinese Center for Disease Control and Prevention. Multiple logistic regression models were used to evaluate the association between 25(OH)D3 and risk of ischemic stroke. ResultsWe included 1079 participants with ischemic stroke and 1079 matched controls. Due to a non-linear relationship, the analyses were stratified by 25(OH)D3. For those with 25(OH)D3 < 20 ng/mL, there was a 15% reduction in the risk of ischemic stroke for each SD increment in 25(OH)D3 (odds ratio, 0.85; 95% confidence interval, 0.73–0.99). Compared with the lowest-tertile group, the risk of ischemic stroke decreased by 39% (odds ratio, 0.61; 95% confidence interval, 0.41–0.89) in the highest-tertile group. Furthermore, two effect modifiers were identified: diabetes and homocysteine level. Although participants with 25(OH)D3 ≥ 20 ng/mL had the lowest risk of ischemic stroke overall, there was no dose-response association within that range. ConclusionsAn inverse dose-response association between 25(OH)D3 and incident risk of ischemic stroke in rural Chinese adults was only observed in those with 25(OH)D3 < 20 ng/mL, along with two effect modifiers. Higher levels of 25(OH)D3 did not confer additional benefit.

Glycerophospholipid metabolism is involved in rheumatoid arthritis pathogenesis by regulating the IL-6/JAK signaling pathway

To explore the metabolic mechanism of differential plasma interleukin (IL)-6 expression in patients with rheumatoid arthritis (RA). A total of 240 RA patients were enrolled in the non-target metabolomics study cohort and 69 healthy volunteers were included as healthy controls (HCs). Plasma IL-6 levels were detected by electrochemiluminescence assay. Plasma metabolites were detected by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Patients with active RA (n = 20) and remissive RA (n = 20) and 20 HCs were enrolled in the targeted validation cohort. Metabolites identified by non-target metabolomics were quantitatively analyzed by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry. Effects of 1-oleoyl-sn-glycero-3-phosphocholine (OGPC) associated with IL-6 on MH7A cells were assessed. After 24-h or 48-h induction by TNF-α, the supernatants were collected for IL-6 quantification by enzyme-linked immunosorbent assay. Furthermore, Western blot was performed to investigate the relative JAK2 and p-JAK2 expressions. With an increasing IL-6 level, OGPC shown to be related to the glycerophospholipid metabolism pathway by Kyoto Encyclopedia of Genes and Genomes analysis displayed a significant decrease. In the validating RA cohort, the OGPC concentrations in remissive RA group and active RA group decreased compared with HC group. OGPC down-regulated IL-6 secretion and p-JAK2 expression in TNF-α-induced MH7A cells in vitro. In conclusion, glycerophospholipid metabolism is the main metabolic pathway associated with the differential IL-6 expression in RA patients. The down-regulated OGPC is a promoting factor for the increased IL-6 plasma level in RA patients, which further affects the downstream JAK signaling pathway.

Comprehensive chemical profiling of the flowers of Citrus aurantium L. var. amara Engl. and uncovering the active ingredients of lipid lowering

The flowers of Citrus aurantium L. var. amara Engl. (FCAVA) is popularly consumed as an edible tea for anti-hyperlipidemia. But the active ingredients are not fully clear. In this study, ultra-high performance liquid chromatography coupled to quadrupole time of flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) with diagnostic product ions and neutral loss filtering strategy were successfully used for comprehensive characterization of chemical components in FCAVA. A total of 228 constituents, including 46 organic acids, 12 coumarins and 170 flavonoids, were tentatively characterized (30 confirmed with reference standards). Among them, nineteen flavonoids in 70 batches of FCAVA from different geographical origins were quantified by UHPLC tandem triple quadrupole mass spectrometry (QQQ-MS), which displayed satisfactory linearity, sensitivity, precision, accuracy, and stability. According to analytical results, the distribution of nineteen flavonoids in different geographical origins of FCAVA was clarified. In addition, the effect on LDL uptake of twenty-five flavonoids was investigated in HepG2 cell. It was found that the acacetin, diosmetin and rutin dose-dependently enhanced LDL uptake in HepG2 cells comparing to control. Furthermore, in a hyperlipidemia C57BL/6J mice model, administration of acacetin, diosmetin and rutin (30 mg/kg/d, intragastric, for three weeks) significantly decreased the levels of total cholesterol (TC), triglyceride (TG) and low density lipoprotein cholesterol (LDL-C) in plasma, respectively. Overall, these findings indicated the potential of FCAVA in the development of functional food or medicine for the prevention and treatment of hyperlipidemia, which could be considered for the improvement of quality standardization of FCAVA.

Fungal mycotoxins reduction by gamma irradiation in naturally contaminated sorghum

The objective of this study was the evaluation of the effects of different gamma irradiation doses on the survival of natural mycoflora as well as on the reduction of mycotoxin contamination (ochratoxin A [OTA] and aflatoxin B1 [AFB1]) in naturally contaminated sorghum samples. Mycotoxin levels were determined by ultra-high-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). The results have demonstrated that the dose of 3 kGy was sufficient to eliminate 90% of the natural fungal load of sorghum. Increasing gamma irradiation dose showed significant effects (p < .05) on initial mycotoxin content. At radiation dose of 10 kGy, maximum reduction of 59% and 32% were achieved in naturally contaminated sorghum for AFB1 and OTA, respectively. The obtained results clearly showed that gamma irradiation can be a promising method to control fungal and mycotoxin contamination in sorghum. Practical applications Sorghum is an important staple cereal crop intended for human foods and animal feeds worldwide. This study investigated the potential application of gamma irradiation to reduce fungal load and the mycotoxins (OTA and AFB1) in naturally contaminated sorghum. The results showed significant decrease in the natural fungal load. The amounts of OTA and AFB1 in sorghum were also reduced by applying this method. The results showed that gamma irradiation was a promising method to control fungal and mycotoxin contamination in sorghum within the permissible dose range applicable to food preservation (≤10 kGy).

Anti-inflammatory and immunomodulatory effects of the extracellular vesicles derived from human umbilical cord mesenchymal stem cells on osteoarthritis via M2 macrophages

Osteoarthritis (OA) is a degenerative illness that greatly impacts the life quality of patients. Currently, the therapeutic approaches for OA are very limited in clinical. The extracellular vesicles (EVs) derived from different mesenchymal stem cells displayed a prominent therapeutic effect on OA. But most EVs have limited resources and the risks of host rejection, immunological response, and etc. Human umbilical cord mesenchymal stem cells (hUCMSCs) hold the advantages of easy availability, minimal immune rejection, and excellent immunomodulatory effects, although hUCMSCs-EVs have seldom been applied in OA. Herein, we investigated the potential immunomodulatory and anti-inflammatory effects of hUCMSCs-EVs on the treatment of OA. In our results, the treatment of hUCMSCs-EVs promoted the polarization of M2-type macrophages and the expression of anti-inflammation-related cytokines (IL-10). Notably, the supernate of M2 macrophages induced by hUCMSCs-EVs inhibited the level of inflammation-associated factors in OA chondrocytes caused by IL-1β. Further, injection of hUCMSCs-EVs in the articular lumen ameliorated progression of OA and exerted chondroprotective potential based on the OA joint model created by the surgical transection of the anterior cruciate ligament (ACLT). In addition, we found five highly enriched miRNAs in hUCMSCs-EVs, including has-miR-122-5p, has-miR-148a-3p, has-miR-486-5p, has-miR-let-7a-5p, and has-miR-100-5p by High-throughput sequencing of miRNAs, with targeted genes mainly enriched in the PI3K-Akt signaling pathway. Furthermore, we also detected the protein abundance of hUCMSCs-EVs using liquidation chromatography with tandem quadrupole mass spectrometry (LC–MS/MS) analysis. Thus, our study indicates that hUCMSCs-EVs can alleviate cartilage degradation during the OA progression, mechanically may through delivering key proteins and modulating the PI3K-Akt signaling pathway mediated by miRNAs to promote polarization of M2 macrophage, exhibiting potent immunomodulatory potential. The current findings suggest that hUCMSCs-EVs might serve as a new reagent for the therapy of OA.Graphical

Synthesis of superparamagnetic MnFe2O4/mSiO2 nanomaterial for degradation of perfluorooctanoic acid by activated persulfate.

In this paper, magnetic MnFe2O4/mSiO2 nanocomposites were successfully synthesized, and the activation performance of the materials for persulfate was evaluated by the degradation efficiency of perfluorooctanoic acid. The structure of the catalyst was proved to be a core-shell structure by several characterization methods. The mesoporous silicon coating can effectively avoid the agglomeration of MnFe2O4 and at the same time increase the contact area with the reactants. A comparison of different catalyst addition conditions demonstrates that MnFe2O4/mSiO2 can effectively activate the persulfate. The optimal reaction conditions were investigated by several key influencing factors. It was experimentally demonstrated that about 90% of PFOA (10mg·L-1) could be decomposed under the conditions of 0.4g·L-1 MnFe2O4/mSiO2 and PS, pH 5.68, and 25°C within 4h; the defluorination rate reached 58.33%. In addition, the cyclability and stability tests demonstrated that MnFe2O4/mSiO2 is a stable material that can be recycled. Furthermore, XPS characterization and radical scavenging experiments demonstrated that sulfate radicals (SO4·-) and hydroxyl radicals (OH) play a major role in the reaction of MnFe2O4/mSiO2 activated PS. Subsequently, the degradation products were detected by high-performance liquid chromatography tandem triple quadrupole mass spectrometry, indicating that the degradation of PFOA is a gradual process of defluorination and decarbonization in the presence of free radicals. Finally, the metal leaching rate is tested to prove that the material meets environmental requirements while reacting efficiently. In conclusion, this study shows that MnFe2O4/mSiO2 is an easily recoverable and highly efficient and stable material that has great potential for PS activation to treat organic pollutants in water.

Analytical Strategies for LC-MS-Based Untargeted and Targeted Metabolomics Approaches Reveal the Entomological Origins of Honey.

A comprehensive liquid chromatography-mass spectrometry (LC-MS)-based metabolomics approach was developed to discriminate honey harvested from Apis mellifera ligustica Spinola (A. mellifera) and Apis cerana cerana Fabricius (A. cerana). Based on an untargeted strategy, ultrahigh-performance liquid chromatography electrospray ionization quadrupole orbitrap high-resolution mass spectrometry (UPLC Q-Orbitrap) was combined with chemometrics techniques to screen and identify tentative markers from A. mellifera and A. cerana honey. In targeted metabolomics analysis, a sensitive method of solid-phase extraction followed by ultrahigh-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-MS/MS) was established for quantifying three markers, and the results showed that 3-amino-2-naphthoic acid and methyl indole-3-acetate could be considered markers of A. cerana honey, as they were present in higher amounts in A. cerana honey than in A. mellifera honey, whereas kynurenic acid was determined to be a marker of A. mellifera honey. This work highlights critical information for the authentication of A. cerana and A. mellifera honey.

Solid‐phase microextraction combined with gas chromatography/triple quadrupole tandem mass spectrometry for determination of nitrated polycyclic aromatic hydrocarbons in sediments

Nitro-polycyclic aromatic hydrocarbons have been detected in various environmental media. However, determination in sediment matrix is challenging due to the lack of a suitable method. In this study, a reliable method for determining 15 nitro-polycyclic aromatic hydrocarbons in sediments was developed based on accelerated solvent extraction and solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry. The accelerated solvent extraction and solid-phase microextraction are sample pre-treatment techniques that have advantages, such as rapid operation and minimal sample volume. Initially, the solid-phase microextraction was optimized using five commercial fibers and from that 65 μm polydimethylsiloxane/divinylbenzene fiber was selected as the best fiber. Further, the accelerated solvent extraction conditions were optimized by Taguchi experimental design, such as extraction temperature (120℃), extraction solvent (dichloromethane), number of cycles (two), static extraction period (4min), and rinse volume (90%). The method parameters, such as limits of quantitation, and intraday and interday accuracy and precision, were in the range of 0.067-1.57ng/g, 75.2-115.2%, 69.9-115.4%, and 1.0-16.5%, respectively. Upon meeting all the quality criteria, the method was applied successfully to analyze real sediment samples. Therefore, our study creates a new prospect for the future application of direct immersion solid-phase microextraction in sediment analysis.

Pollution Characteristics and Risk Assessment of Nitrated Polycyclic Aromatic Hydrocarbons in the Atmosphere of Guangdong-Hong Kong-Macao Greater Bay Area

To investigate the pollution characteristics and sources of nitrated polycyclic aromatic hydrocarbons (NPAHs) in Guangdong-Hong Kong-Macao Greater Bay Area (GBA), 44 ambient air samples were collected using the active sampling method, which were then determined via gas chromatography-triple quadrupole tandem mass spectrometry. The main results showed that filters, polyurethane foam, and XAD-2 resin were the essential materials for sampling NPAHs in ambient air in order to characterize the pollution status accurately. The levels of ρ(Σ18NPAHs) in ambient air at GBA ranged from 162 pg·m-3 to 2094 pg·m-3, and the average levels of ρ(Σ18NPAHs) were (675±430) pg·m-3 in summer and (637±349) pg·m-3 in winter. NPAHs were widely found in the ambient air of GBA and were dominated by 1-nitronaphthalene (220 pg·m-3), 2-nitronaphthalene (146 pg·m-3), 9-nitroanthracene (105 pg·m-3), and 2-nitrofluoranthene (72 pg·m-3). The congener profile characteristics of NPAHs in summer and winter were similar. The gas/particle partitioning characteristics of NPAHs revealed that dicyclic and tricyclic NPAHs tend to occur in the gas phase, and tetracyclic NPAHs tend to be adsorbed in the particle phase. The fraction of NPAHs concentrations in the particulate fraction of their total atmospheric concentrations increased with the increase in their molecular weight. In winter, NPAHs tend to be adsorbed in the particle phase, whereas in summer, NPAHs tend to exist in the gas phase. Based on the ratios of characteristic pollutants, in both the summer and winter season, photochemical reactions were the main source of NPAHs in the atmosphere of GBA and were primarily generated by the reaction of the hydroxyl radical in the daytime. The carcinogenic risk value calculation showed that the current carcinogenic risk of NPAHs in the ambient air of GBA was controllable.

Modifying current thin-film microextraction (TFME) solutions for analyzing prohibited substances: Evaluating new coatings using liquid chromatography

For identifying and quantifying prohibited substances, solid-phase microextraction (SPME) continues to arouse interest as a sample preparation method. However, the practical implementation of this method in routine laboratory testing is currently hindered by the limited number of coatings compatible with the ubiquitous high-performance liquid chromatography (HPLC) systems. Only octadecyl (C18) and polydimethylsiloxane/divinylbenzene ligands are currently marketed for this purpose. To address this situation, the present study evaluated 12 HPLC-compatible coatings, including several chemistries not currently used in this application. The stationary phases of SPME devices in the geometry of thin film-coated blades were prepared by applying silica particles bonded with various functional ligands (C18, octyl, phenyl-hexyl, 3-cyanopropyl, benzenesulfonic acid, and selected combinations of these), as well as unbonded silica, to a metal support. Most of these chemistries have not been previously used as microextraction coatings. The 48 most commonly misused substances were selected to assess the extraction efficacy of each coating, and eight desorption solvent compositions were used to optimize the desorption conditions. All samples were analyzed using an HPLC system coupled with triple quadrupole tandem mass spectrometry. This evaluation enables selection of the best-performing coatings for quantifying prohibited substances and investigates the relationship between extraction efficacy and the physicochemical characteristics of the analytes. Ultimately, using the most suitable coatings is essential for trace-level analysis of chemically diverse prohibited substances.