Quasi-molecular Ions Research Articles

Evaluation of efficacy of Dihuang Baoyuan Granules for diabetes mellitus and composition and in vivo distribution analysis based on UHPLC-LTQ-Orbitrap MS

Dihuang Baoyuan Granules is a prescription endorsed by HU Tianbao, a renowned and elderly Chinese medicine practitioner from Beijing, and has demonstrated definite clinical efficacy. The composition of this prescription is intricate as it includes 7 distinct herbal medicines. This study aims to analyze the chemical composition of Dihuang Baoyuan Granules, evaluate its efficacy in the treatment of diabetes and analyze the distribution of the drug components in the plasma, liver, and kidney after administration. The findings will serve as a reference for future research on pharmacodynamic substances of this prescription. UHPLC-LTQ-Orbitrap MS was employed to analyze the main chemical components of Dihuang Baoyuan Granules. A Waters ACQUITY Premier HSS T3 column(2.1 mm×100 mm, 1.8 μm) was used for chromatographic separation with 0.1% formic acid(A)-acetonitrile(B) as the mobile phases in a gradient elution at a flow rate of 0.3 mL·min~(-1). Electrospray ionization(ESI) source was used to acquire data in positive and negative ion modes. Furthermore, a rat model of diabetes mellitus was established by feeding with a high-sugar high-fat diet, and injection with streptozocin at a dose of 35 mg·kg~(-1), and the modeled rats were then administrated with Dihuang Baoyuan Granules. The fasting blood glucose, hemoglobin A1c, and other relevant indicators were measured, and the substances present in the plasma, liver, and kidney were identified. By reference to quasi-molecular ions, MS/MS fragment ions, MS spectra of reference substances, and compound information in available reports, 191 components were identified in Dihuang Baoyuan Granules, including 29 alkaloids, 24 flavonoids, 22 organic acids, 16 amino acids, 12 terpenes, 11 steroid saponins, 9 sugars, 8 phenylethanoid glycosides, 8 nucleosides, 2 phenylpropanoids, and 49 others compounds. Eighty-three chemical components were identified in rat plasma, 109 in the liver, and 98 in the kidney. Component identification and characterization of Dihuang Baoyuan Granules in vitro and in vivo provide efficacy information and guidance for the basic research on the pharmacodynamic substances and further clinical application of this prescription.

Retention time-independent strategy for screening pesticide residues in herbs based on a fingerprint database and all ion fragmentation acquisition with LC-QTOF MS.

A retention time (RT)-independent strategy for nontargeted screening of pesticide residues in herbs was exploited using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF MS). The core of this strategy is a fingerprint database coupled with a data-independent acquisition (DIA) scan mode of all ion fragmentation (AIF). In the fingerprint database, a total of 150 pesticides with quasimolecular ions and fragment ions at five-level collision energies were collected as qualified ions for screening. During the data acquisition, the AIF scan was performed via real unbiased full-spectrum MS/MS acquisition. Six herb matrices spiked with 30 banned pesticides were used to evaluate the applicability of the strategy in real samples. The use of the narrow ion mass extraction window (10 mDa) and the narrow RT window (0.1 min) enabled the effective extraction of spectra from noisy backgrounds and the discovery of suspected pesticides via similarity matching of filtered qualified ions. On average, more than 11/30 of pesticides at 1 ng mL-1 and more than 23/30 of pesticides at 10 ng mL-1 or lower could be screened out in each matrix using at least two qualified ions. In addition, the AIF mode exhibited superior anti-interference capability compared to data-dependent acquisition (DDA) and sequential window acquisition of all theoretical mass spectra (SWATH), as determined by comparing the limits of screening (LOSs) of 30 banned pesticides spiked into Isatidis Folium. Finally, the developed strategy was applied to screen pesticide residues in extracts of Ganoderma and Foeniculi Fructus. Phorate-sulfone and phorate-sulfoxide were found in Ganoderma, as well as terbufos-sulfone and terbufos-sulfoxide were found in Foeniculi Fructus. In conclusion, the developed RT-independent strategy based on a fingerprint database and AIF acquisition with LC-QTOF MS seems to be one of the most efficient tools for the analysis of nontargeted pesticide residues in complicated matrices.

Light antiproton one-electron quasi-molecular ions within the relativistic A-DKB method.

In the present work, two quasi-molecular compounds each involving one antiproton and one electron (p̄), He+-p̄ and H-p̄, are investigated. Using completely relativistic calculations within the finite-basis method adapted to systems with axial symmetry, the adiabatic potential curves are constructed by numerically solving the two-center Dirac equation. The binding energies of electron are obtained as a function of the inter-nuclear distance and compared with the corresponding nonrelativistic values and relativistic leading-order corrections calculated in the framework of other approaches. A semantic analysis of antiproton quasi-molecular ions with compounds containing a proton (p) instead of an antiproton is given. The advantages of the A-DKB method are demonstrated.

Discovery, isolation and structural identification of alkaloid glycosides in six traditional Chinese medicine such as Coptis chinensis

Alkaloids are important active ingredients occurring in many traditional Chinese medicines, and alkaloid glycosides are one of their existence forms. The introduction of saccharide units improves the water solubility of alkaloid glycosides thus presenting better biological activity.Because of the low content in plants, alkaloid glycosides have been not comprehensively studied. In this study, ultrahigh performance liquid chromatography-quadrupole time of flight-tandem mass spectrometry(UPLC-QTOF-MS/MS) was employed to identify and analyze the alkaloid glycosides in Coptis chinensis, Phellodendron chinense, Menispermum dauricum, Sinomenium acutum, Tinospora sagittata and Stephania tetrandra. The results showed that except Tinospora sagittata, the other five herbal medicines contained alkaloid glycosides. Furthermore, the alkaloid glycosides in each herbal medicine were identified based on UV absorption spectra, quasimolecular ion peaks in MS, fragment ions information in the MS/MS, and previous literature reports. A total of 42 alkaloid glycosides were identified. More alkaloid glycosides were identified in C. chinensis and Menispermum dauricum, and eleven in C. chinensis were potential new compounds. Furthermore, the alkaloid glycosides in the water extract of C. chinensis were coarsely se-parated by macroporous adsorption resin, purified by column chromatography with D151 cation exchange resin, ODS and MCI, combined with semi-preparative high performance liquid chromatography. Two new alkaloid glycosides were obtained, and their structures were identified by mass spectrometry and NMR data as(S)-7-hydroxy-1-(p-hydroxybenzyl)-2,2-N,N-dimethyl-1,2,3,4-tetrahydroisoquinoline-6-O-β-D-glucopyranoside and(S)-N-methyltetrahydropalmatubine-9-O-β-D-glucopyranoside, respectively. This study is of great significance for enriching the information about the chemical composition and the in-depth development of C. chinensis. Meanwhile, it can provide a reference for rapid identification and isolation of alkaloid glycosides from other Chinese herbal medicines.

The inhibition effects of chlorogenic acid on the formation of colored oxidation products of (-)-epigallocatechin gallate under enzymatic oxidation.

Untargeted Liquid chromatography tandem mass spectrometry (LC-MS) based metabolomics in combination with UV-visible and colorimeter was applied in identifying critical colored enzymatically oxidized products of (-)-epigallocatechin gallate (EGCG). Pearson correlation coefficient analysis between marker compounds and a* value was conducted, and then a series of colored oxidation products were targeted and subsequently identified by diode array detection and mass fragmentation ions. The quinone of oolongtheanin 3-O'-gallate degraded product with quasi-molecular mass ion at m/z 711 was identified as a critical colored oxidation product of single EGCG. To explore the effect of chlorogenic acid on the formation of colored EGCG enzymatic oxidation products, the variation of oxidation products on the oolongtheanin pathway was semi-quantitatively determined. The result showed chlorogenic acid significantly inhibited the formation of colored oxidation products, thus lightened the color of EGCG oxidation mixture. The addition of chlorogenic acid influences the process of tea polyphenols' enzymatic oxidation.

N-acetyldopamine oligomers from Periplaneta americana with anti-inflammatory and vasorelaxant effects and their spatial distribution visualized by mass spectrometry imaging

Ethnopharmacological relevancePeriplaneta americana is a medicinal insect that has been applied to promote blood circulation and remove blood stasis based on traditional Chinese medicine (TCM) for a long time. Its modern preparation, Xinmailong injection, was adopted for the treatment of congestive heart failure (CHF). The bioactive constituents of P. americana and their correlation with its traditional uses need further investigation. Aim of the studyThis study aimed to elucidate the N-acetyldopamine (NADA) oligomers from P. american, determine their spatial distribution, and investigate their anti-inflammatory and vasorelaxant effects to provide scientific evidence supporting the clinical use of this medicinal insect. Material and methodsNADA oligomers were isolated from the CH2Cl2: CH3OH (2:1) extract of P. americana, through sequential chromatographic methods including silica gel, Sephadex LH-20, preparative HPLC, and chiral-phase separation. Their structures were determined by HRESIMS, 1D and 2D NMR spectroscopic analysis, chiral resolution, and calculated electronic circular dichroism analysis. With the aid of atmospheric pressure scanning matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI), the isolated compounds in a spatial profile within P. americana were identified. NO production was measured to assess anti-inflammatory activity. Vasorelaxant activity assessments were performed on the norepinephrine-precontracted 3rd-order mesenteric arteries. ResultsSeven new NADA trimers, peridopamines A−G (1−7), two new NADA dimers, peridopamines H and I (8 and 9), and six known NADA derivatives (10−15), were obtained from P. americana. The trimers and dimers were detected and showed similar pattern of distribution with accumulation in peripheral and rigid parts of P. americana, based on quasimolecular ion AP-SMALDI MS images of sections from the whole body and dissected areas of the insect. Furthermore, the anti-inflammatory and vasorelaxant effects of isolated compounds were investigated. Compounds 8 and 9 presented significant and moderate anti-inflammatory potentials, respectively. Compounds 8, 10, 12 and 15 possess significant vasorelaxant potentials at concentrations correlated with EC50 values of 6.7–23.7 μM. ConclusionFifteen NADA oligomers were isolated from P. americana. The distribution of these compounds was visualized by AP-SMALDI imaging experiments and NADA oligomers were mainly observed in peripheral parts. Bioassays showed that the tested compounds had anti-inflammatory and vasorelaxant activities, which indicated that NADA oligomers are active ingredients of this insect-based TCM and have potential for the treatment of cardiovascular disease.

Integrated strategy facilitates rapid in-depth chemome characterization of traditional Chinese medicine prescriptions: Shengbai oral liquid as a case.

Chemome characterization is the prerequisite for either therapeutic mechanism clarification or quality control of traditional Chinese medicine prescriptions (TCMPs). Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) currently serves as the most popular analytical tool; however, chemome characterization is still challenged by MS/MS spectral acquisition and post-acquisition data processing. Here, an integrated strategy was proposed for in-depth chemome clarification of Shengbai oral liquid (SBOL). Gas phase ion fractionation with staggered mass ranges was demonstrated to be the superior acquisition method regarding MS2 spectrum coverage in this study, and narrower mass range further advanced coverage. To facilitate information extraction, all ingredient materials were measured in parallel to form an in-house library, where each MS1 -MS2 item generated a square mass-to-charge ratio (m/z) frame to capture the tagged identity and each chemical family produced a pentagon frame for mass defect features to accomplish chemical analogs-targeted quasi-molecular ion extraction. Square m/z frame imprinting captured 355 identities, while mass defect frames extracted 275 compounds. Attributing to comprehensive MS2 spectrum acquisition and efficient data processing, 355 components were captured and tentatively identified, resulting in a clarified chemical composition for SBOL. Therefore, the proposed strategy should be meaningful for the chemome characterization of TCMPs.

Determination of 41 veterinary drug residues in livestock and poultry meat using a composite purification system coupled with direct analysis in real time-tandem mass spectrometry

In a market environment where food safety problems still occur despite repeated prohibitions, food safety problems caused by veterinary drug residues and biological safety problems caused by the transfer of drug resistance have attracted much attention. Herein, a method based on a compound purification system coupled with direct analysis in real time-tandem mass spectrometry (DART-MS/MS) was established to determine 41 different types of veterinary drug residues in livestock and poultry products. First, a single-standard solution sampling method was used to optimize the selection of the best quasi-molecular ion, two daughter ions, and their cone-hole and collision voltages; qualitative and quantitative ion pairs are composed of a quasi-molecular ion and its corresponding daughter ion. The abundance ratios of the drug compounds in standard solutions of the solvent and matrix mixtures were then calculated according to the requirements of the European Union 2002/657 specification. DART-MS/MS was subsequently developed for the accurate characterization and quantitative analysis of the veterinary drugs. Finally, a composite purification pretreatment system was formed by combining the primary secondary amine (PSA) and octadecyl bonded silica gel (C18) of a QuEChERS technology with multiwalled carbon nanotubes (MWCNTs) to achieve the one-step purification of the drug compounds. The influence of the key parameters of the DART ion source on the determination of the drugs was investigated using the peak areas of the quantitative ions as the criterion. The optimum conditions were as follows: ion source temperature of 350 ℃, 12-Dip-it Samplers module, sample injection speed of 0.6 mm/s, and external vacuum pump pressure of -75 kPa. According to the differences in the dissociation constant (pKa) ranges of the 41 types of veterinary drug compounds and the characteristics of the sample matrixes, the extraction solvent, matrix-dispersing solvent, and purification method were optimized based on the recovery. The extraction solvent was 1.0% acetonitrile formate solution, and the pretreatment column included MWCNTs containing 50 mg of PSA and 50 mg of C18. The three chloramphenicol drugs showed a linear relationship in the ranges of 0.5-20 μg/L with correlation coefficients of 0.9995-0.9997,and the detection and quantification limits of three chloramphenicol drugs were 0.1 and 0.5 μg/kg, respectively. The 38 other drugs, including quinolones, sulfonamides, and nitro-imidazoles showed a linear relationship in the ranges of 2-200 μg/L with correlation coefficients of 0.9979-0.9999, and the detection and quantification limits of the 38 other drugs were 0.5 and 2.0 μg/kg, respectively. The recoveries of the 41 veterinary drugs at low, medium, and high spiked levels in chicken, pork, beef, and mutton samples were 80.0%-109.6%, with intra- and inter-day precisions of 0.3%-6.8% and 0.4%-7.0%, respectively. A total of 100 batches of animal meat (pork, chicken, beef, and mutton; 25 batches each) and known positive samples were simultaneously analyzed using the national standard method and the detection method established in this study. Sulfadiazine (89.2, 78.1, and 105.3 μg/kg) was detected in three batches of pork samples, and sarafloxacin (56.3, 102.0 μg/kg) was detected in two batches of chicken samples and no veterinary drugs were detected in the other samples; both methods yielded consistent results for known positive samples. The proposed method is rapid, simple, sensitive, environmentally friendly, and suitable for the simultaneous screening and detection of multiple veterinary drug residues in animal meat.

UPLC-QTOF-MS/MS assisted UPLC-TQ-MS/MS strategy to comparatively investigate the rat pharmacokinetics of N-acetyldopamine oligomers derived from Cicadae Periostracum

Cicadae Periostracum (CP), the slough molted from the nymph of Cryptotympana pustulata, is a widely used medicinal material in traditional Chinese medicine (TCM). N-acetyldopamine oligomers (NAOs), the homologues of acetyldopamine, including N-acetyldopamine dimers/trimers/tetramers/pentamers (NADs/NATrs/NATes/NAPs), side-chain isomer of dimers/trimers (SCIDs/SCITrs), are major bioactive ingredients of CP. However, owing to commercially unavailable reference substances of all NAOs, simultaneous quantification of these NAOs in biological samples is difficult, and thus their pharmacokinetics are still unknown. In this study, a comprehensive strategy for simultaneous quantification/semi-quantification of NAOs in plasma with single N-acetyldopamine dimer A (NAD-A) as reference substance was established and comparatively investigated their pharmacokinetics after oral administration of pure NAD-A and two types of CP extracts, i.e., post-molting-washed slough (CP-WAT) and pre-molting-washed slough (CP-WBT). A UPLC-QTOF-MS/MS assisted UPLC-TQ-MS/MS strategy was developed to quantify NAOs in rat plasma. NAOs in CP extract were qualitatively characterized by UPLC-QTOF-MS/MS, then the quasi-molecular ions and characteristic fragment ions of the identified NAOs by UPLC-QTOF-MS/MS were transferred to UPLC-TQ-MS/MS as parent-daughter ion pairs for MRM mode quantification of the NAOs, and the method was validated with single NAD-A for quantifying NAD-A and semi-quantifying other NAOs in plasma. The established method was applied to compare the pharmacokinetics of NAOs after oral administration of NAD-A and the extracts of CP-WBT/CP-WAT respectively. Six quasi-molecular ions and characteristic fragment ion m/z 192.1 were characterized by UPLC-QTOF-MS/MS and transferred to be the parent-daughter ion pairs for UPLC-TQ-MS/MS analysis of six kinds of NAOs. For the pharmacokinetics, NAD-A showed double peaks absorption character when administered with single compound, but with higher relative bioavailability when administered with CP extracts with the similar dosage. Compared with CP-WAT, NAOs in CP-WBT reached the maximum plasma concentration in much shorter time.

Molecular Characterization of Hydrocarbons in Petroleum by Ultrahigh-Resolution Mass Spectrometry

The progress in ultrahigh-resolution mass spectrometry (UHRMS) and related technologies has significantly promoted the development of petroleomics. The study of petroleomics has greatly broadened our knowledge of the composition of petroleum at the molecular level, especially heavy fractions that cannot be analyzed by gas chromatography (GC)-based methods. To date, heteroatom-containing (O, N, S, and metal atoms) compounds in petroleum have been studied extensively by UHRMS. Nevertheless, the main components of petroleum, hydrocarbon compounds, have remained out of reach of petroleomics characterization for a long time because they are too difficult to be softly and efficiently ionized for UHRMS analysis. It is undoubtedly the case that petroleum hydrocarbons should not be the missing part of petroleomics characterization since they play important roles not only as feeding pools for various high value-added petroleum products but also as critical biomarkers for geochemistry studies. Here, the most recent breakthroughs in petroleomics characterization of hydrocarbon compounds using UHRMS rather than conventional methods have been reviewed. Innovations of soft ionization methods can transform non-polar hydrocarbon molecules into molecular ions or quasi-molecular ions that are reachable for UHRMS without fragmentation. The development of data processing methods has assisted the decoding of the complicated UHRMS data to visualize the molecular composition and structure of hydrocarbon compounds. These advances make it possible to see the whole picture of petroleum compositions, from light distillation fractions to heavy distillation fractions, and from small volatile molecules to large non-volatile ones. The applications of UHRMS-based methods for petroleomics characterization of hydrocarbon compounds in crude oils and various petroleum samples including fuel oil, slurry, and even asphaltene have made a great contribution to petrochemistry and geochemistry studies, especially in the fields of molecular refining and biomarker discovery.

Component identification and analysis in vivo of Sanhan Huashi formula

Sanhan Huashi formula(SHF) is the intermediate of a newly approved traditional Chinese medicine(TCM) Sanhan Huashi Granules for the treatment of COVID-19 infection. The chemical composition of SHF is complex since it contains 20 single herbal medicines. In this study, UHPLC-Orbitrap Exploris 240 was used to identify the chemical components in SHF and in rat plasma, lung and feces after oral administration of SHF, and heat map was plotted for characterizing the distribution of the chemical components. Chromatographic separation was conducted on a Waters ACQUITY UPLC BEH C_(18)(2.1 mm×100 mm, 1.7 μm) using 0.1% formic acid(A)-acetonitrile(B) as mobile phases in a gradient elution. Electrospray ionization(ESI) source was used to acquire data in positive and negative mode. By reference to quasi-molecular ions and MS/MS fragment ions and in combination with MS spectra of reference substances and compound information in literature reports, 80 components were identified in SHF, including 14 flavonoids, 13 coumarins, 5 lignans, 12 amino-compounds, 6 terpenes and 30 other compounds; 40 chemical components were identified in rat plasma, 27 in lung and 56 in feces. Component identification and characterization of SHF in vitro and in vivo lay foundations for disclosure of its pharmacodynamic substances and elucidation of the scientific connotation.

Structure Analysis of the Interfering Substance N-methyl-2-phenylpropan-1-amine of Methamphetamine in Wastewater.

To analyze the chemical structure of the interfering substance that affects the result of methamphetamine analysis in wastewater. A combination of GC-MS and liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was used to analyze the mass spectrum characteristics of the interfering substance that affects the result of methamphetamine analysis and to infer its possible structure. Liquid chromatography-triple quadrupole-mass spectrometry (LC-TQ-MS) was used to confirm the control material. Using LC-QTOF-MS in positive electrospray ionization (ESI+) mode, the mass-to-charge ratio (m/z) of quasi-molecular ion in the MS1 mass spectrometry of interfering substance was identical to that of methamphetamine, indicating that the interfering substance was probably an isomer of methamphetamine. The MS2 mass spectra obtained at three collision energies of 15 V, 30 V and 45 V were highly similar to methamphetamine, suggesting that the interfering substance contained methylamino and benzyl groups. Further analysis using GC-MS in electron impact (EI) ionization mode showed that the base peak in the mass spectrum of the interfering substance was at m/z 44. The interfering substance was confirmed to be N-methyl-2-phenylpropan-1-amine by compared with the standard reference. The chemical structure of N-methyl-2-phenylpropan-1-amine is highly similar to methamphetamine, which is easy to cause interference for the detection of trace amounts of methamphetamine in wastewater using LC-TQ-MS. Therefore, in the actual analysis, the chromatographic retention time can be used to distinguish between N-methyl-2-phenylpropan-1-amine and methamphetamine.

Nontarget analysis and characterization of alkylamides in electrical product plastics by gas chromatography-positive chemical ionization quadrupole-orbitrap high-resolution mass spectrometry and quasi-molecular ion screening and anchoring algorithm

Alkylamides are used as plastic additives in various materials and products, potentially posing risks to human health and the environment. Besides reported alkylamides in plastics, many unknown alkylamides may exist in various plastics, which are needing identification and characterization. This study performed nontarget analysis of alkylamides in electrical product plastics by gas chromatography-positive chemical ionization high-resolution mass spectrometry in full scan mode and an in-house developed data-processing algorithm. The algorithm was based on exact mass discrepancies and signal intensities of specific fragment and adduct ions of alkylamides, and was able to efficiently screen and anchor quasi-molecular ions. As a whole, 36 alkylamides were identified, of which 7 were found in all the plastics and 14 were observed in ≥ 2 plastics. The content distributions were elucidated with normalized abundances of quasi-molecular ions of alkylamides. Oleamide showed chromatographic peaks with the highest abundances in individual samples and was the most abundant alkylamide in all the plastics, of which the normalized abundances accounted for 57.42–70.06% of the total abundances of all alkylamides. Besides, (2E)-2-hexenamide, palmitamide and stearamide showed relatively high abundances, of which the relative abundances were 6.99–25.79%. The high abundances together with predicted environmental behaviors and toxicities indicate that alkylamides in plastics are worthy of further in-depth research. The nontarget analysis method including the instrumental analysis and data-processing algorithm can be applied to identification and characterization of alkylamides in more diverse matrices. In addition, the analysis results for the first time provide knowledge about the specific characteristics and relative content distributions of alkylamides in electrical product plastics from a comprehensive perspective.

Massive intoxication due to cocaine adulterated with carfentanil

To identify the causal agent of the massive intoxication occurred in February 2022 in Buenos Aires, with 98 hospitalized victims and 24 deaths. The first victims presented the following signs: miosis, shock, sensory depression, respiratory distress (bradypnea), psychomotor excitement, seizures, and cardiorespiratory arrest. Some showed a typical opiomimetic sign: “wood chest”. Given the parasympathetic signs, the victims were treated with Naloxone at high doses, responding favourably and with a continuous infusion drip of 10 mg in 250 mL at a flow rate of 11 mL/h. The latter to prevent them from deteriorating when they waked up. All the cases had in common having inhaled a line of cocaine acquired from the same dealer. Seized powder samples were preliminarily analysed by HPTLC and UPLC-DAD (Acquity System-Waters Corp, USA). A cocaine standard (LGC Std, Lot. 979337, USA) was used. Subsequently, for the detailed analysis of components, a fractionation was made by extracting the soluble components in chloroform and the soluble and insoluble fractions were analysed by 1H and 13 C NMR on a Bruker A Neo 500 spectrometer (1H 500 MHz, 13C 125 MHz). The chloroform insoluble fraction was further analysed by LC-MS with exact mass detection on a Bruker micrOTOF-Q II spectrometer coupled to an Agilent 1200 HPLC. Structure confirmation was performed by MRM (multiple reaction monitoring), and MS/MS fragmentation. UPLC-DAD analysis showed a purity of 51.6% for COC, the rest being mostly sorbitol as cutting material (confirmed by NMR, as noted below). In the soluble fraction, where the spectra were measured in deuterochloroform solution, the NMR spectra showed the characteristic signals of cocaine hydrochloride and small amounts of cinnamyl cocaine (CIN) that usually accompanies cocaine hydrochloride and truxillines. (The latter very important to infer the origin of cocaine). In the insoluble fraction the main component was identified as sorbitol from its 1H and 13C NMR spectra (in DMSO-d6). A small remnant of cocaine and cinnamyl cocaine (CIN) was also observed. On the other hand, this fraction was analysed by LC-MS, observing 7 relevant peaks: cocaine, benzoylecgonine, cinnamyl cocaine (cis and trans), truxillines and a minor component of m/z 395.2316 that corresponds to the formula C24H31N2O3 (calculated 395,2329) coincident with the [M + H]+ quasi-molecular ion of carfentanil. Structure confirmation was performed by MRM, and fragmentation by MS/MS of the M + H ion, observing the characteristic fragments of the carfentanil structure including the two confirmatory ions of m/z 335.2123 (calculated for C22H27N2O+ 335,2118) and m/z 246.1489 (calculated for C15H20NO2+ 246,1489). Quantitative analysis was performed by NMR for the COC/CIN ratio and from LC-MS for the CIN/Carfentanil ratio. Giving an estimated result of 30 μg/100 mg of pure cocaine. The toxic dose for humans is unknown, although would be less than 1 mg based on animal studies and known fentanyl lethal cases (estimated lethal dose is 20 μg) (Casale et al., 2017). The therapeutic treatment followed by the victims and the results observed allowed us to focus on opiomimetics, as the most relevant factor in the cause of the 24 deaths. The high-resolution methods applied allowed us to confirm cocaine in a percentage of purity close to half of the total powder. Carfentanil was confirmed by MRM analysis and in an amount of approximately 30 μg/100 mg of pure cocaine. Based on the data collected in the case, the consumption of cocaine was about 200 mg, therefore, in the proportion of purity, each line contained about 30 μg of carfentanil. So, for 400 mg of powder consumed, carfentanil would be found at 60 μg. Therefore, we estimated the toxic dose for this episode between 30–60 μg.

Benefits of Ion Mobility Separation in GC-APCI-HRMS Screening: From the Construction of a CCS Library to the Application to Real-World Samples.

The performance of gas chromatography (GC) combined with the improved identification properties of ion mobility separation coupled to high-resolution mass spectrometry (IMS-HRMS) is presented as a promising approach for the monitoring of (semi)volatile compounds in complex matrices. The soft ionization promoted by an atmospheric pressure chemical ionization (APCI) source designed for GC preserves the molecular and/or quasi-molecular ion information enabling a rapid, sensitive, and efficient wide-scope screening. Additionally, ion mobility separation (IMS) separates species of interest from coeluting matrix interferences and/or resolves isomers based on their charge, shape, and size, making IMS-derived collision cross section (CCS) a robust and matrix-independent parameter comparable between instruments. In this way, GC-APCI-IMS-HRMS becomes a powerful approach for both target and suspect screening due to the improvements in (tentative) identifications. In this work, mobility data for 264 relevant multiclass organic pollutants in environmental and food-safety fields were collected by coupling GC-APCI with IMS-HRMS, generating CCS information for molecular ion and/or protonated molecules and some in-source fragments. The identification power of GC-APCI-IMS-HRMS for the studied compounds was assessed in complex-matrix samples, including fish feed extracts, surface waters, and different fruit and vegetable samples.

Coding recognition of the dose-effect interdependence of small biomolecules encrypted on paired chromatographic-based microassay arrays.

The discovery of small biomolecules has suffered from the lack of a comprehensive framework to express the intrinsic correlation between bioactivity and the contribution from small molecules in complex samples with molecular and bioactivity diversity. Here, by mapping a sample’s 2D-HPTLC fingerprint to microplates, paired chromatographic-based microassay arrays are created, which can be used as quasi-chips to characterize multiple attributes of chromatographic components; as the array differential expression of the bioactivity and molecular attributes of irregular chromatographic spots for dose–effect interdependent encoding; and also as the automatic-collimated array mosaics of the multi-attributes of each component itself encrypted by its chromatographic fingerprint. Based on this homologous framework, we propose a correlating recognition strategy for small biomolecules through their self-consistent chromatographic behavior characteristics. In the approach, the small biomolecule recognition in diverse compounds is transformed into a constraint satisfaction problem, which is addressed through examining the dose–effect interdependence of the homologous 2D code pairs by an array matching algorithm, instead of preparing diverse compound monomers of complex test samples for identification item-by-item. Furthermore, considering the dose–effect interdependent 2D code pairs as links and the digital-specific quasimolecular ions as nodes, an extendable self-consistent framework that correlates mammalian cell phenotypic and target-based bioassays with small biomolecules is established. Therefore, the small molecule contributions and the correlations of bioactivities, as well as their pathways, can be comprehensively revealed, so as to improve the reliability and efficiency of screening. This strategy was successfully applied to galangal, and demonstrated the high-throughput digital preliminary screening of small biomolecules in a natural product.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00216-022-04162-9.

Determination of chlorpropham residues in animal-derived foods by solid phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry

建立了固相萃取-超高效液相色谱-串联质谱法(SPE-UHPLC-MS/MS)测定动物源食品中氯苯胺灵残留的分析方法。动物源食品经乙腈溶液提取、正己烷脱脂、ProElut PLS固相萃取柱富集净化,采用C18色谱柱进行分离,以0.2%(v/v)甲酸水溶液和乙腈为流动相进行梯度洗脱,采用电喷雾电离、正离子模式扫描,多反应监测模式(MRM)检测,基质匹配标准曲线外标法定量。研究通过对不同填料的固相萃取柱的考察,最终选择了ProElut PLS固相萃取柱,其能对动物源食品复杂基质中的氯苯胺灵进行有效富集和净化;通过考察3种规格的C18柱对氯苯胺灵的保留能力和出峰效果,选择了Agilent ZORBAX SB-C18(150 mm×2.1 mm, 5 μm)作为氯苯胺灵的分离色谱柱;通过考察氯苯胺灵在正负两种质谱电离模式下的响应情况,选择了正离子模式,确定氯苯胺灵一级质谱准分子离子和相应的碎片离子。结果表明:氯苯胺灵在0.5~100.0 μg/L范围内呈良好的线性关系,相关系数(r2)均不低于0.9929;方法定量限(LOQ)为3 μg/kg(S/N≥10);以猪肉、牛奶、牛肉、鸡肉、鸭肉、鸡蛋、鸡胗、鸭蛋、猪腰、猪肝、牛肝、羊肉、鸭胗共13种动物源食品为基质,在0.003、0.006、0.060 mg/kg添加水平下,氯苯胺灵的平均回收率为74.9%~97.6%,相对标准偏差(RSD)为2.9%~9.5%(n=6)。本方法前处理简便易行、基质干扰小、灵敏度高、准确性高,适用于多种动物源食品中氯苯胺灵的定性和定量检测。

Multiplexed Analysis of Endogenous Guanidino Compounds via Isotope-Coded Doubly Charged Labeling: Application to Lung Cancer Tissues as a Case.

Endogenous guanidino compounds (GCs), nitrogen-containing metabolites, have very important physiological activities and participate in biochemical processes. Therefore, accurately characterizing the distribution of endogenous GCs and monitoring their concentration variations are of great significance. In this work, a new derivatization reagent, 4,4'-bis[3-(dimethylamino)propyl]benzyl (BDMAPB), with isotope-coded reagents was designed and synthesized for doubly charged labeling of GCs. BDMAPB-derivatized GCs not only promote the MS signal but also form multicharged quasimolecular ions and abundant fragment ions. With this reagent, an isotope-coded doubly charged labeling (ICDCL) strategy was developed for endogenous GCs with high-resolution liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF MS). The core of this methodology is a 4-fold multiplexed set of [d0]-/[d4]-/[d8]-/[d12]-BDMAPB that yields isotope-coded derivatized GCs. Following a methodological assessment, good linear responses in the range of 25 nM to 1 μM with correlation coefficients over 0.99 were achieved. The limit of detection and the limit of quantitation were below 5 and 25 nM, respectively. The intra- and interday precisions were less than 18%, and the accuracy was in the range of 77.3-122.0%. The percentage recovery in tissues was in the range of 85.1-113.7%. The results indicate that the developed method facilitates long-term testing and ensures accuracy and reliability. Finally, the method was applied for the simultaneous analysis of endogenous GCs in four types of lung tissues (solid adenocarcinoma, solid squamous-cell carcinoma, ground-glass carcinoma, and paracancerous tissues) for absolute quantification, nontargeted screening, and metabolic difference analysis. It is strongly believed that ICDCL combined with isotope-coded BDMAPB will benefit the analysis and study of endogenous GCs.

A multi-analytical approach for the identification of the natural resin from the Ming tomb in Shaanxi, China

Several well-preserved polychrome lacquered coffins were found in Zhang Dong family’s tombs in Shaanxi, China, rare in the history of archaeological excavation. In the lacquered coffins, a large amount of dark solid of suspected natural resin was unearthed with mysterious compositions and uses, exerting a tremendous fascination on archaeologists. In this work, a new method was explored for the identification of the suspected natural resin, mainly based on thermogravimetry (TG), elemental analysis (EA), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) and Fourier transform infrared spectrometry (FT-IR). The results suggested that the sample was mainly composed of organics with a content of 81.66% and little inorganics with a content of 2.21% by water excluded. Rosin with the main component of abietic acid (molecular formula C20H30O2) was identified as the principal component of the sample. Dehydrogenated abietic acid (DHA) and other oxides were also tested out. FT-IR confirmed the identification results. SEM revealed the rough surfaces evenly covered with holes of similar sizes. The use of this method directly obtained integral quasi-molecular ion fragments and molecular components of the sample. As a result, intricate multi-stage mass spectrometry is avoidable, which dramatically simplifies the analysis procedure. This approach is simple and effective for the identification of precious relic samples, requires no references, and has potential for the analysis of these kinds of unknown samples. Especially, for the first time, EA is used to identify natural resins from archaeological sites.

Precursor ion approach for simultaneous determination of nonethoxylated and ethoxylated alkylsulfate surfactants

We present a new liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of sodium lauryl sulfate and sodium laureth sulfate homologues in the range of alkyl chain length C12–C16 with 0–5 ethoxy groups. The method is based on scanning the precursor ions fragmenting to m/z 80 and 97 (Precursor Ion Scanning mode), which makes it specific for species with easily cleavable sulfate groups. By monitoring fragmentation of thus discovered quasi-molecular ions we were able to unequivocally identify all sulfate species present in complex mixtures of alkyl and alkyl-ether sulfates with molecular weight ranging from 200 to 600 m/z. Because of the intrinsic sulfate-sensitivity, the presented method can be also applied to non-sodium salts of alkyl- and alkyl-ether sulfates (e.g. ammonium, mono- or triethanolamine, etc.), which are often used by cosmetic manufacturers to justify the misleading SLS- and SLES-free claims (where SLS and SLES refer to sodium lauryl sulfate and sodium laureth sulfate, respectively). The use of reversed phase liquid chromatography (RPLC) column with C4 instead of C18 shortened significantly the overall analysis time and allowed us to use a semiquantitative method (based on single standard for Quantitative Analysis of Multi-component System, QAMS) to determine several SLS and SLES homologues in one run with the limit of quantification (LOQ) = 0.4 µg/mL and of detection (LOD) in the range 0.12–0.97 µg/mL. The method was successfully applied to 17 commercially available cosmetic/household products allowing verification of their manufacturers’ declarations.