Chromatography Quadrupole Orbitrap High-resolution Mass Research Articles

Quantitation of trace polyfunctional thiols in wine by liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry in parallel reaction monitoring

Polyfunctional thiols are key contributors to wine aroma due to their extremely low odor thresholds, and their quantitative analysis remains challenging as a result of their ultratrace concentrations and high reactivity. This work presents the first method based on ultra-high-performance liquid chromatography (UHPLC) coupled to quadrupole Orbitrap high-resolution mass spectrometry (HRMS) in parallel reaction monitoring (PRM) mode for quantifying thiols at nanograms per liter (ng/L) levels in wine. Thiols in wine were derivatized using 4,4′-dithiodipyridine and isolated by liquid-liquid extraction. This protocol allowed rapid sample preparation with minimum labor input and low consumable expenses. Instrumental analysis was conducted using UHPLC–quadrupole Orbitrap HRMS in PRM mode. Twenty thiol analytes, including literature-known, recently identified, and novel thiols were selected and validated by the optimized method in three wine matrices. The overall analytical performances demonstrated by this method were equivalent, and in most cases, greater than many previously developed GC–MS or LC–MS methods. The validated method was applied to analyze a selection of wines in which 12 thiols were quantified.

Chemical composition and absorption characteristics of Raw and Prepared Cassiae Semen extracts based on ultra-high-performance liquid chromatography-quadrupole Orbitrap high-resolution mass spectrometry.

In traditional Chinese medicine, the two commodity forms of Cassiae Semen Raw and Prepared Cassiae Semen, exert different clinical applications, in which Prepared Cassiae Semen is commonly used to treat liver and eye diseases. However, the material basis of Raw and Prepared Cassiae Semen remains unclear due to the limited studies on their overall composition and metabolism in vivo. In this study, an integrated analysis strategy based on ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry was established to systematically screen the prototype and metabolite constituents of Raw and Prepared Cassiae Semen. Automatic matching analysis of metabolites was performed on Compound Discoverer software based on the function of predicting metabolites. Using this strategy, a total of 77 compounds in Raw Cassiae Semen and 71 compounds in Prepared Cassiae Semen were identified. Furthermore, in vivo study, 46 prototype components and 104 metabolites from the Raw Cassiae Semen group and 41 prototype components and 87 metabolites from the Prepared Cassiae Semen group were unambiguously or preliminarily identified in mice (plasma, urine, feces, eye, and liver). This is the first study of chemical component analysis and in vivo metabolite profiling of Raw and Prepared Cassiae Semen.

Comparison of chemical compositions of different parts of Xanthoceras sorbifolium seeds based on UHPLC-Q-Orbitrap HRMS

Xanthoceras sorbifolium seeds have a wide range of applications in the food and pharmaceutical industries. To compare and analyze the chemical compositions of different parts of X. sorbifolium seeds and explore the potential value and research prospects of non-medicinal parts, this study used ultra-high-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry(UHPLC-Q-Orbitrap HRMS) to detect the chemical composition of various parts of the seeds. A total of 82 components were preliminary identified from X. sorbifolium seeds, including 5 amino acids, 4 polyphenols, 3 phenylpropionic acids, 7 organic acids, 15 flavonoids, 6 glycosides, and 23 saponins. Mass spectrometry molecular networking(MN) analysis was conducted on the results from different parts of the seeds, revealing significant differences in the components of the seed kernel, seed coat, and seed shell. The saponins and flavonoids in the seed kernel were superior in terms of variety and content to those in the seed coat and shell. Based on the chromatographic peaks of different parts from multiple batches of samples, multivariate statistical analysis was carried out. Four differential components were determined using HPLC, and the average content of these components in the seed kernel, seed coat, and seed shell were as follows: 0.183 6, 0.887 4, and 1.440 1 mg·g~(-1) for fraxin; 0.035 8, 0.124 1, and 0.044 5 mg·g~(-1) for catechin; 0.032 9, 0.072 0, and 0.221 5 mg·g~(-1) for fraxetin; 0.435 9, 2.114 7, and 0.259 7 mg·g~(-1) for epicatechin. The results showed that catechin and fraxetin had relatively low content in all parts, while fraxin had higher content in the seed coat and seed shell, and epicatechin had higher content in the seed kernel and seed coat. Therefore, the seed coat and seed shell possess certain development value. This study provides rapid analysis and comparison of the chemical compositions of different parts of X. sorbifolium seeds, which offers an experimental basis for the research and clinical application of medicinal substances in X. sorbifolium seeds.

Chemical composition and absorption characteristics of Angong Niuhuang Pill based on two-dimensional ultra-high-performance liquid chromatography-quadrupole Orbitrap high-resolution mass spectrometry

Angong Niuhuang Pill (ANP) is a traditional Chinese medicine (TCM) formula with significant clinical efficacy in the treatment of stroke. Due to its complex composition, little attention has been directed toward the analysis of chemical composition and absorption characteristics of ANP. In this study, a reliable two-dimensional ultra-high-performance liquid chromatography (2D-UHPLC) coupled with quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS) method was established to characterize the chemical constituents in ANP as well as the prototype components and metabolites absorbed in plasma, urine, feces, and brain tissues after oral administration. The prototype components were identified by a high mass accuracy (within 5 ppm) and MS/MS data based on online, local, and ANP self-built databases. The metabolites were predicted and identified using Compound Discoverer metabolic platform. A total of 154 compounds mainly including 37 flavonoids, 35 alkaioids, 19 organic acid, 19 bile acid, 32 terpenoids and 12 others were identified in this way. In addition, 60 prototype components mainly including flavonoids, alkaioids, organic acid, terpenoids and 164 metabolites were confirmed or preliminarily identified in rats. The metabolic pathways phase I reaction (hydration, reduction, oxidation, demethylation, and hydroxylation) and phase II reaction (acetylation, stearyl conjugation, and methylation) for the absorbed constituents were explored and summarized. This is the first systematic and comprehensive chemical characterization in ANP and its metabolism in vivo by 2D-UHPLC-Q-Orbitrap HRMS. This approach provides an effective strategy for the characterization of compounds and metabolites in traditional Chinese medicine formulas.

Identification, Quantitation, and Sensory Evaluation of Thiols in Bordeaux Red Wine with Characteristic Aging Bouquet.

Great Bordeaux red wines are known for their distinctive aging bouquet. However, the nature of volatile chemicals underpinning this sensory expression is not fully understood. This work investigated the empyreumatic aging bouquet of a collection of premium Bordeaux red wines using silver-ion (Ag+) solid-phase extraction, cryogenic heart-cutting multidimensional gas chromatography mass spectrometry/olfactometry, and comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. In doing so, a substantial number of "meaty" odors were revealed. Three detected "meaty" notes were tentatively or unequivocally attributed to furan thiols. Among them, 2-methyltetrahydrofuran-3-thiol (1) with a pleasant "meaty" aroma was reported in wine for the first time. Its trans isomer (trans-1a) was resolved from its racemate by chemical modification, which confirmed its presence in wine. The odor detection threshold of trans-1a in the model wine was determined at 55 ng/L. Moreover, an additive effect between 1 and literature-known 2-methyl-3-furanthiol was observed. By a new ultra high-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry method, the concentration of trans-1a, in addition to those of 2-methyl-3-furanthiol and 2-furfuryl thiol, was measured in the wines at ng/L levels.

Fabrication of a magnetic metal-organic framework/covalent organic framework composite for simultaneous magnetic solid-phase extraction of seventeen trace quinolones residues in meats

Effective capture of quinolones (QNs) in animal-derived food is a vital procedure for food safety monitoring. However, the lack of adsorption specificity and difficult to recycle in complex substrate conditions have been major problems for most of the adsorbents. In this work, a magnetic Fe3O4/MOF/COF composite (named Fe3O4@NH2−MIL-125@TpPa-SO3H) was successfully synthesized with good magnetic responsiveness and conspicuous affinity towards QNs. The Fe3O4/MOF/COF composite was used as a magnetic solid-phase extraction (MSPE) adsorbent for pretreatment and determination of QNs in meat samples. Under optimal MSPE conditions in combination with high performance liquid chromatography-quadrupole orbitrap high resolution mass spectrometer (HPLC-Q-Orbitrap HRMS), the proposed method had good linearity (R2 ≥ 0.9978) from 0.01 to 100ng g−1, low limits of detection (0.0016 to 0.0940ng g−1), good precision with relative standard deviations lower than 5.8%. This method was effectively applied to the detection of 17 QNs in the spiked pork, chicken and beef samples with satisfactory recoveries from 83.9 to 106.2%. The separation selectivity mainly due to the π–π interaction, hydrogen bonding, and electrostatic attraction between QNs and the sulfonic acid and amino functional groups of the composite. After verification, the stability and reusability of the composite meet the requirements of complex matrix sample pretreatment. The developed MSPE method based on the magnetic Fe3O4/MOF/COF composite provided an ideal sample pretreatment alternative for determining trace QNs in complex matrixes with selectivity, simplicity, rapidity, and efficiency.

Isolation, structural characterization and sporicidal properties of Baelezcin A, a novel cyclic lipopeptide from Bacillus velezensis SJ100083 against gray mold.

Postharvest gray mold induced by Botrytis cinerea seriously affects cherry quality, resulting in huge economic losses. The aim of this study was to isolate and purify a novel antifungal compound from the endophytic Bacillus velezensis SJ100083 of cherries to prevent postharvest gray mold. In this study, Baelezcin A, extracted and purified from Bacillus velezensis SJ100083, was found effective in suppressing gray mold on cherries. Furthermore, the structure of Baelezcin A was identified as a novel cyclic lipopeptide with molecular formula of C52 H91 N7 O13 through ultra-high-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS) and nuclear magnetic resonance (NMR). Baelezcin A treatment at 25 mg L-1 significantly decreased the disease incidence and severity of cherry gray mold, the antifungal mechanism of which was attributed to the accumulation of reactive oxygen species within the spores and the leakage of mycelium cytoplasmal contents, resulting in a low rate of spore germination. Moreover, it was proven to be biologically safe within a certain range by MTT assays. Our study demonstrated that Baelezcin A from the culture of Bacillus velezensis SJ100083 may be a promising fruit preservative for controlling postharvest gray mold caused by Botrytis cinerea. © 2023 Society of Chemical Industry.

Renshen Baidu Powder Attenuated Intestinal Inflammation and Apoptosis in Ulcerative Colitis Rats through the Inhibition of PI3K/AKT/NF-κB Signaling Pathway.

Objective Renshen Baidu Powder (RBP) is a famous classic compound of traditional Chinese medicine (TCM) and is commonly used for treating ulcerative colitis (UC). However, the pharmacological mechanism of RBP in treating UC remains unclear. This study investigates the possible mechanism of RBP for UC treatment by network pharmacological analysis and rat validation. Methods First, the main chemical constituents of RBP were identified using ultrahigh-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS). Then, we obtained targets of identified compounds from the SwissTargetPrediction database and targets associated with UC from GeneCards database. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze the metabolism-related signaling pathways affected by RBP. Hematoxylin-eosin (HE) staining was used to observe the pathological change of colon in UC rats after treating RBP, and terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP Nick end labeling (TUNEL) staining was used to detect apoptosis after RBP treatment. The enzyme-linked immunosorbent assay (ELISA) was employed to evaluate cytokine levels of TNF-α, IL-1β, and IL-6. The protein expressions of Bax, Bcl-2, PI3K, AKT, and NF-κB in colonic tissue were detected using immunohistochemistry (IHC). Real-time quantitative polymerase chain reaction (RT-QPCR) was employed to evaluate mRNA expression of PI3K, AKT, and NF-κB. Results We found a total of 24 main compounds and 329 potential targets related to UC. According to KEGG results, 3 main pathways were identified as responsible for UC, including PI3K-AKT, HIF-1, and VEGF signaling pathway. Animal experiments showed that RBP treatment significantly attenuated colon damage in rats with UC. Mechanistically, RBP could inhibit PI3K/AKT/NF-κB pathway; decrease cell apoptosis; and downregulate the expression of TNF-α, IL-1β, and IL-6. Conclusions This study demonstrated that RBP may exert anti-inflammatory and antiapoptotic therapeutic benefits in UC by regulating the PI3K/AKT/NF-κB signaling pathways, providing a scientific basis for understanding the mechanism of RBP against UC.

Multi-residue analysis of 206 pesticides in grass forage by the one-step quick, easy, cheap, effective, rugged, and safe method combined with ultrahigh-performance liquid chromatography quadrupole orbitrap mass spectrometry.

A novel method for detecting pesticide multi-residue in grass forage (alfalfa and oat) was established based on the one-step automatic extractionand purification technology of quick, easy, cheap, effective, rugged, and safe combined with ultrahigh-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry. The crushed sample was extracted with acetonitrile with 1% acetate, followed by a cleanup step with a primary-secondary amine, octadecylsilane, and graphitized carbon black. The extraction and purification were carried out using the one-step automatic pretreatment equipment. The target pesticides were acquired in positive ion electrospray ionization mode and full scan/data dependent secondary scan mode. The calibration curve shows good linearity over the corresponding concentration range, with the coefficient of determination greater than 0.99. The screening detection limits were 0.5-50μg/kg, and the limit of quantification for the 206 pesticides was set at 1-50μg/kg. At the spiking levels of one, two, and 10 times of limit of quantification, more than 95% of pesticides had recovery between 70-120%, with a relative standard deviation ≤20%. The method was proved to be simple, rapid, high-sensitivity, and could be routinely used for the high throughput screening and quantitative analysis of pesticide residues in alfalfa and oat.

Rapid determination of 93 banned industrial dyes in beverage, fish, cookie using solid-supported liquid–liquid extraction and ultrahigh-performance liquid chromatography quadrupole orbitrap high-resolution mass spectrometry

Banned industrial dyes are composed of a large number of chemicals with diverse physical and chemical properties, making their simultaneous determination a challenging task. A one-step extraction and purification of 93 banned industrial dyes from beverage, fish and cookie sample methods was proposed by using solid supported liquid–liquid extraction (SLE). The extract was analyzed by ultrahigh-performance liquid chromatography quadrupole orbitrap high–resolution mass spectrometry (UPLC-Q-Orbitrap-HRMS). The quantitative and qualitative mode adopts Q-Orbitrap-HRMS full scan MS (full scan MS1) and data-dependent MS/MS (dd-MS2) acquisition mode. The mass resolution was screened under 70,000 FWHM for full-scan MS1 and 35,000 FWHM for dd-MS2. Linearity was observed in the range of 0.01 ∼ 0.5 μg/mL and the limits of quantification were 0.04 ∼ 0.2 mg/kg for 93 dyes. The average recoveries were 70.5–105.8%, with RSD ≤ 10%. The proposed method has the ability to simultaneously screen many banned dyes in foods with high throughput, sensitivity and reliability.

Molecular mechanism of Mare Nectaris and magnetic field on the formation of ethyl carbamate during 19 years aging of Feng-flavor Baijiu

Ethyl carbamate (EC) is carcinogen occurring naturally in fermented foods, while the EC formation pattern in Feng-flavor Baijiu during Mare Nectaris storage and magnetic field treatment remains controversial. In this work, variation of EC in Mare Nectaris and magnetic field were investigated for the first time through ultra high performance liquid chromatography quadrupole-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). Quantification results revealed that EC decreased significantly in the stage of 3–9 years and kept at 12.4 μg L−1 after 10 years of aging. Arginine succinate synthase (ASS) and urease were deemed as vital factors for EC decomposition. Degradation effetc of EC in 250 mT is simillar to that of EC in Baijiu stored in Mare Nectaris for 8 years. This is due to that aging process was accelerated by magnetic field and the content of total acid in Baijiu was increased, creating a favorable environment for decomposition of EC and urea.

Molecular mechanism of high pressure shear grinding on Feng-flavour Chinese Baijiu ageing

Ultrahigh-pressure homogenization is a powerful technique for accelerating Baijiu ageing. In this study, the molecular mechanism of artificial ageing was thoroughly investigated utilizing foodomics combined with a mass spectrum information optimization program. Various characterizations of compounds in the ageing process were performed through ultra high performance liquid chromatography quadrupole-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap) based colloid theoretics. High-pressure shear grinding provides a high-pressure and high-temperature environment for Baijiu, accelerating the formation of flavour compounds and the decomposition of odour and harmful substances, thus improving the sensory characteristics of Feng-flavour Baijiu and shortening the ageing time. A total of 2069 substances were identified according to fragment spectra and Bayesian network model-based peak distribution. Molecules with VIP > 1, including 14 esters, 10 acids, 4 ketones, 3 aldehydes, 2 alcohols and 2 phenols, were quantified as potential markers of chemometric analysis. A novel prediction model for Baijiu ageing degree was furnished, and ageing years of Feng-flavour Chinese Baijiu were accurately predicted by factor analysis with KMO 0.784 and a polynomial regression model with r 0.94. The results demonstrated that in 400 bar, fresh distilled Baijiu could reach a natural ageing effect of 6.43 years, which was consistent with the sensory evaluation.

The inhibitory effect of Periplaneta americana L. on hepatocellular carcinoma: Explore the anti-hepatocellular carcinoma active site and its mechanism of action

Ethnopharmacological relevanceThe American cockroach (Periplaneta americana L.) belongs to the family Blattidae, order Blattodea, and class Insecta. Its medicinal history in China spans thousands of years. In recent years, the anti-tumour activity of American cockroach has gradually attracted the attention of researchers and has a good application prospect in the treatment of tumours. Periplaneta americana has been found to contain proteins, peptides, amino acids and nucleosides. Pharmacological studies have shown that P. americana has anti-tumour, tissue repair, immunoregulatory and other activities. In this study, we investigated the chemical composition and mechanism of action of its active site against hepatocellular carcinoma. Materials and methodsWe adopted ultra-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry (UPLC–Q-Orbitrap HRMS), measuring the accurate relative molecular mass, fragment ion peak, chromatographic retention time and reference substance information of the compound obtained by HRMS, to identify the chemical components of the anti-hepatocellular carcinoma (HCC) active site of P. americana based on data from relevant literature. We used western blotting (WB) to detect the expression levels of phosphoinositide 3-kinase (PI3K), phosphorylated protein kinase B (p-Akt) and Akt in the PI3K/Akt pathway and further study the molecular mechanism of the active site of P. americana against HCC. ResultsUPLC–Q-Orbitrap HRMS identified 35 compounds from the active site of P. americana. Of these, 10 were amino acids, 1 was an alkaloid, 6 were nucleosides and their bases, 4 were dipeptides and cyclic dipeptides, 8 were organic acids, 2 were isoflavones and 4 were other compounds; 8 of these compounds were confirmed by comparison with the reference substance. The WB results showed that the relative expression levels of PI3K and p-Akt protein in the active site of P. americana in the medium-dose (concentration, 0.15624 mg⋅mL−1) and high-dose (concentration, 0.31250 mg⋅mL−1) experimental groups were significantly reduced compared with the blank control group (P < 0.05 or P < 0.01), whereas the expression level of Akt protein did not significantly change amongst the groups (P > 0.05). ConclusionThis study found that the anti-HCC active site of P. americana is composed of multiple components that can reduce the relative expression of PI3K and p-Akt protein. It exerts its anti-HCC effect by regulating the PI3K/Akt pathway.

Serum concentrations of neonicotinoids, and their associations with lipid molecules of the general residents in Wuxi City, Eastern China

Exposure to neonicotinoid insecticides (NNIs) was proven to be harmful to organisms, however, there is a dearth of information regarding their occurrence and adverse effects on the general residents. Here, n = 120 human serum samples were collected from the same area of Wuxi city, Eastern China, and these serum samples were further analyzed for nine NNIs and nine target lipid molecules by use of ultrahigh performance liquid chromatography-quadrupole orbitrap high-resolution mass spectrometer. We observed that four out of nine NNIs exhibited relatively high detection frequencies (DF), and these NNIs were imidacloprid (IMI; DF = 28.3%), clothianidin (CLO; 16.7%), thiacloprid (THI; 14.2%), and acetamiprid (ACE; 12.5%), respectively, with 95th concentrations ranging from 32.0 to 427 pg/mL. Median concentrations of imidacloprid-equivalent total neonicotinoids (IMIeq) and ∑7NNI were 46.6 pg/mL and 26 pg/mL, respectively. Five out of nine lipid molecules exhibited higher levels, that were docosahexaenoic acid [FA(22:6)], 18:0 phosphocholine [LysoPC(18:0)], 18:0 phosphoethanolamine [LysoPE(18:0)], D18:1–18:0 sphingomyelin [SM(d18:1/18:0)], and 18:1–18:1 diglycerol [DG(18:1/18:1)], respectively. More interestingly, we observed statistically significant correlations (student’s t-test, one-way ANOVA, or Mann-Whitney test; p < 0.05) between NNI levels and population characteristics (i.e. age, smoking, and health status). Beyond that, we also observed statistically significant correlations between levels of selected NNIs (CLO, ACE, or THI) and lipid molecules [LysoPE(18:0), SM(d18:1/18:0), and DG(18:1/18:1)]. Collectively, for the first time, we provided the information on contamination levels of NNIs in serum samples of general residents in China and demonstrated the associations between concentrations of NNIs and levels of lipid molecular species.

Fully automated identification and quantification of five polar pesticides in groundwater by isotope dilution-online solid phase extraction coupled with high-performance liquid chromatography-quadrupole Orbitrap high-resolution mass spectrometry.

A fully automated method for identification and quantification of five polar pesticides in groundwater by isotope dilution-online solid-phase extraction (SPE) coupled with high-performance liquid chromatography-quadrupole Orbitrap high-resolution mass spectrometry was developed. After one step of filtration, an aliquot of a 7.5-ml water sample was automatedly preconcentrated and purified on a turbulent Cyclone SPE column. The analytes were eluted in backflush mode, then separated on an analytical column and acquired by full MS/dd-MS2 scan in negative and positive ions mode. The major parameters for sample loading, cleanup, and elution were optimized in detail. Preconcentration and ionization efficiency were highly improved by using 0.1% acid solution in the mobile phase. The method provided good linearity of calibration coefficients (R2 > 0.995), sensitive method limits of detection (0.5-10.0 ng/L), accurate mass spectra (within 5 ppm error), satisfactory matrix spiking recoveries (98.4% to 109%), and high precision (intraday/interday relative standard deviations 1.57-8.90%). The method was successfully applied to analyze large batch groundwater of National Groundwater Monitoring Project and suspect screening of potential pesticides in groundwater. The study provided a practical alternative for a simple, robust, sensitive, and accurate identification and qualification of five polar pesticides in groundwater.

Target Quantification and Semi-Target Screening of Undesirable Substances in Pear Juices Using Ultra-High-Performance Liquid Chromatography-Quadrupole Orbitrap Mass Spectrometry.

Fruit juices are common products in modern diets due to the supply of vegetal nutrients combined with its tastiness. Nevertheless, potential contaminants, such as mycotoxins and pesticides, can be present in commercial products due to a potential carry-over. Therefore, the aim of this study was to investigate for the first time the presence of 14 Fusarium mycotoxins using a quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction followed by an ultra-high-performance liquid chromatography-quadrupole Orbitrap high-resolution mass spectrometry in 21 pear juice samples from Italian markets. Up to nine different mycotoxins were detected, particularly an extensive presence of zearalenone (67%, n = 21, mean value = 0.88 ng/mL). Emerging Fusarium mycotoxins enniatins B, B1, A, and A1 were also detected. Additionally, 77 pesticide residues were tentatively identified through a retrospective analysis based on a mass spectral library. The prevalent presence of some non-approved pesticides, such as ethoxyquin (64%, n = 21) and triazophos (55%, n = 21), must be highlighted. The results obtained indicate an extensive contamination of marketed pear juice with undesirable compounds, and they should be taken into consideration when performing risk assessment studies.

A sensitive method for simultaneous determination of 12 classes of per- and polyfluoroalkyl substances (PFASs) in groundwater by ultrahigh performance liquid chromatography coupled with quadrupole orbitrap high resolution mass spectrometry

Per- and polyfluoroalkyl substances (PFASs) comprise a large group of chemicals with diverse physicochemical properties, which make their simultaneous determination a challenging task. A trace analytical method based on ultrahigh performance liquid chromatography-quadrupole Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was developed for simultaneous determination of 54 PFASs belonging to 12 classes in groundwater, including 24 perfluorocarbons and 30 precursors. This method provided good linearity of calibration standards (R2 > 0.99), excellent method limits of quantification (MLOQs) (0.5–250 pg/L), satisfactory matrix spiking recoveries (63%–148%), high precision (intra-day relative standard deviations (RSDs) 1.4–11.4%, inter-day RSDs 1.6–12.9%, and inter-week RSDs 2.1–12.7%), and short runtime (13 min), suitable for high throughput studies. The newly established method was successfully applied to detect PFASs in the groundwater samples collected from Hebei Province, China. Twenty PFASs were detected with the total concentration of 0.3–32.9 ng/L, indicating the contamination level similar to that in drinking water. The dominant PFASs were perfluorobutanesulfonate (PFBS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA) and perfluorooctanoic acid (PFOA). In addition, 6:2 fluorotelomer phosphate diester (6:2 diPAP) and 6:2 fluorotelomer sulfonate (6:2 FTS) were found as the major precursors. The total PFAS concentrations were lower than the cumulative permissible limit of 70 ng/L for PFOS and PFOA recommended by the United States Environmental Protection Agency (USEPA) for drinking water in 2016. In a nutshell, this study provided a fast and sensitive method based on HRMS for the simultaneous analysis of a wide range of PFASs, present at trace levels in groundwater samples.

Target quantification and semi-target screening of halogenated carboxylic acids in drinking water using ultra-high performance liquid chromatography-quadrupole orbitrap high-resolution mass spectrometry

To monitor the existing and emerging halogenated carboxylic acids (HCAs) in drinking water, a sensitive and rapid ultra-high performance liquid chromatography-quadrupole orbitrap high-resolution mass spectrometry method for simultaneous target quantification of 10 haloacetic acids (HAAs) and semi-target screening of 19 HCAs was developed. After filtration, drinking water samples were injected into the instrument. HCAs were separated on an HSS T3 column and detected by a type of non-target scan in the electrospray ionization negative mode. For target quantification of 10 HAAs, good linearity was obtained and the correlation coefficients were higher than 0.995. The limits of detection were in the range of 0.050–2.0 µg/L. The recoveries were in the range of 89.7%-108%, 83.4%-121%, 77.1%-116% and 80.2%-104% at levels of 2.5, 5.0, 10 and 20 µg/L, respectively, with relative standard deviations of 1.26%-16.9%. For semi-target screening of 19 HCAs, several criteria including accurate m/z, predicted retention time, deduced fragment ions and simulated isotope pattern were used for identification. The method was applied to analyzing 41 drinking water samples successfully. Five HAAs were detected by target quantification, with dichloroacetic acid and trichloroacetic acid exceeding the limits suggested by the U.S. Environmental Protection Agency and the World Health Organization. Eight HCAs were preliminary identified by semi-target screening, and three of them were further confirmed with reference standards purchased later.

Residue Distribution and Depletion of Ractopamine in Goat Tissues After Exposure to Growth-Promoting Dose.

The objectives of the present study was to investigated the ractopamine (RAC) distribution and depletion process in various tissues of goat including liver, kidney, spleen, lung, heart, fat, bile, brain and the eyes. The experiment was carried out on 21 goats (18 treated and 3 controls). Treated goats were orally administered RAC in a dose of 1 mg/kg body mass per day for last 28 days and randomly sacrificed on withdrawal days of 0.25, 1, 3, 7, 14 and 21. RAC in all matrices were determined by ultra-high performance liquid chromatography-quadrupole orbitrap high resolution mass spectrometry. After 21 days treatment discontinuation, the levels of RAC in bile reached at 13.48 ± 3.36 mg/L, which was significantly higher than that in the other tissues. The concentrations of RAC were followed by kidney, the excretory organ and liver, the major metabolic organ (4.49 ± 0.16 mg/kg for kidney and 1.81 ± 0.11 mg/kg for liver, respectively). The residual concentration of the drug in the eyes of goat was less than that in bile, kidney, liver, lung and spleen on withdrawal days 0.25. RAC residues was higher than the limits of detection = 0.15 μg/mL in liver on Day 21. These findings demonstrated that liver can serve as an alimentary matrix and as a matrix for the control of RAC abuse hypothetically except for urine.