Stepped-up development of accelerator mass spectrometry method for the detection of ^(60)Fe with the HI-13 tandem accelerator

The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae.Lunar samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides such as^(60)Fe.In this work,we stepped up the development of an accelerator mass spectrometry(AMS)method for detecting^(60)Fe using the HI-13tandem accelerator at the China Institute of Atomic Energy(CIAE).Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph,a Wien filter with a maximum voltage of±60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide^(60)Fe.A 1μm thick Si_(3)N_(4) foil was installed in front of the Q3D as an energy degrader.For particle detection,a multi-anode gas ionization chamber was mounted at the center of the focal plane of the spectrograph.Finally,an^(60)Fe sample with an abundance of 1.125×10^(-10)was used to test the new AMS system.These results indicate that^(60)Fe can be clearly distinguished from the isobar^(60)Ni.The sensitivity was assessed to be better than 4.3×10^(-14)based on blank sample measurements lasting 5.8 h,and the sensitivity could,in principle,be expected to be approximately 2.5×10^(-15)when the data were accumulated for 100 h,which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.

Research on the Upper Limit of Accuracy for Predicting Theoretical Tandem Mass Spectrometry

In recent years, numerous theoretical tandem mass spectrometry prediction methods have been proposed, yet a systematic study and evaluation of their theoretical accuracy limits have not been conducted. If the accuracy of current methods approaches this limit, further exploration of new prediction techniques may become redundant. Conversely, a need for more precise prediction methods or models may be indicated. In this study, we have experimentally analyzed the limits of accuracy at different numbers of ions and parameters using repeated spectral pairs and integrating various similarity metrics. Results show significant achievements in accuracy for backbone ion methods with room for improvement. In contrast, full-spectrum prediction methods exhibit greater potential relative to the theoretical accuracy limit. Additionally, findings highlight the significant impact of normalized collision energy and instrument type on prediction accuracy, underscoring the importance of considering these factors in future theoretical tandem mass spectrometry predictions.

Ultra-soft Desorption Assisted Mass Spectrometry using Picosecond Infrared Laser for the Detection of lons in the Liquid Surface

To identify the species in liquid surface using mass spectrometry,we must eliminate or reduce interferences during the vaporization or desorption of the species from the liquid surface.It is much more challenging to isolate the ionic,larger species from the liquid surface,because of the frangible structures and the higher solvation energies of those species.Here we demonstrate a new mass spectrometry in which the ionic species at the liquid surface can be desorbed with ultrasoft infrared picosecond laser pulses while the liquid surface is not breached.This laser desorption assisted mass spectrometry is not only a powerful tool to detect the fragile species but also promising to investigate vibrational energy transfer dynamics in the liquid surface.

Determination of Ten Kinds of Alpha-2 Agonists Residues in Animal Derived Food by UHPLC-Triple Quadrupole/Composite Linear Ion Trap Mass Spectrometry

[Objectives]The paper was to establish an ultra high performance liquid chromatography-quadrupole/linear ion trap complex mass spectrometry for the determination of 10 kinds ofα2-receptor agonists in animal derived food.[Methods]The samples were extracted with sodium carbonate buffer solution and ethyl acetate,and analyzed by mass spectrometry after solid phase extraction and high performance liquid chromatography separation.[Results]Ten kinds ofα2-receptor agonists showed a good linear relationship in the range of 1-100μg/mL,with the average recovery of over 69%and the relative standard deviation less than 8.32%.The detection limit of 10 kinds of α_(2)-receptor agonists was up to 1μg/kg.[Conclusions]The method has good selectivity and strong anti-interference ability,and can meet the requirements of 10 kinds ofα2-receptor agonists residues in animal derived food.

Determination of Voriconazole in Human Plasma by Liquid Chromatography Tandem Mass Spectrometry: Application in Therapeutic Drug Monitoring

A sensitive, accurate and robust Liquid Chromatography Tandem Mass Spectrometry method has been developed and validated to measure voriconazole trough levels in human plasma. The plasma samples were mixed with fluconazole as an Internal Standard and directed to protein precipitation and drug extraction. An aliquot of 1 μl was injected into the chromatographic system and separated by the Acquity BEH C18 column at a flow rate of 0.30 ml/min in a gradient mobile phase consisting of acetonitrile, Ultrapure water (UPW), methanol and formic acid. Voriconazole was detected by a Triple Quadrupole Detector (TQD) operating on Multiple Reaction Monitoring (MRM) and a positive ion mode Electrospray ionization (ESI) Q1 mass: 350.1 m/z, Q3 mass: 281.1 m/z. Method linearity of the calibration curve (0.10 - 8.00 μg/ml) indicated a correlation coefficient r ≥ 0.99. The intra and inter-assay accuracy was within 85% - 115% and the intra and inter-assay precision was ≤5.76%. Voriconazole recovery percentage was between 97.69 - 119.62%. The method was successively applied in routine voriconazole TDM.

Determination of Oleuropein in Cosmetics by Ultra Performance Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

An ultrahigh performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-MS/MS)was established to quickly and accurately determine the content of oleuropein in cosmetics.The samples were extracted with methanol-aqueous solution,and the mobile phase with methanol-formic acid solution(0.1 mol/L)=40∶60 was separated by Agilent ZORBAX Eclipse Plus C18(2.1 mm×50 mm×1.8μm-Micron)column temperature 30℃,flow rate 0.3 mL/min.The MS end was detected by electrospray negative mode ionization(ESI-)and multiple reaction monitoring(MRM)mode.The results show a good linear relationship in the range of 0.002~5 mg/L,with a correlation coefficient R2 of 0.999,5.Method recovery range from 84.2%~107.6%and the relative standard deviation RSD is 5.8%.The detection time is 5 min,the detection limit is 0.000,6 mg/L,and the limit of quantification is 0.002 mg/L.This method has the advantages of convenient operation,low quantification limit,high precision and good repeatability,and is suitable for measuring the content of oleuropein in many kinds of cosmetics.

Determination of egg and milk allergen in food products by liquid chromatography-tandem mass spectrometry based on signature peptides and isotope-labeled internal standard

The aim of this work was to develop a liquid chromatography-tandem mass spectrometry method for the determination of milk allergen and egg allergen in food products.Signature peptides GGLEPINFQTAADQAR,VGINYWLAHK,VLVLDTDYK,FFVAPFPEVFGK,and NAVPITPTLNR were confirmed and synthesized as the quantitative peptide of ovalbumin,α-lactalbumin,β-lactoglobulin,α_(S1)-casein andα_(S2)-casein,the relative isotope-labeled internal standards were used in the quantitative analysis.Linear range was in the range of0.5-5000.0 nmol/L for egg and milk allergen in bread,cake,cookie,rice crust and wheat flour samples with free from egg and milk,the limits of detection of milk allergens and egg allergen were in the range between0.94 mg/100 g and 56.71 mg/100 g,limits of quantification of milk allergens and egg allergen were in the range between 2.36 mg/100 g and 141.78 mg/100 g.The recoveries ranged from 76.7%to 122.8%,the relative standard deviations were in the range of 1.60%-15.60%.The developed method has been successfully used for the detection of egg and milk allergen in various food samples.

Simultaneous Determination of 14 β-Receptor Agonists Residues in Mutton by High Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS)

[Objectives]A high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)method was established for the determination of 14β-receptor agonist residues in mutton.[Methods]Samples were hydrolyzed byβ-glucuronidase and extracted with 5%acetic acid-acetonitrile(1:99,V/V)solution.An Eclipse plus C 18 column was used for separation,and the MRM mode was used for qualitative analysis,and the external standard method was used for quantitative analysis of matrix standard solutions.[Results]Under the optimal conditions,the retention time of the 14 kinds ofβ-receptor agonists ranged from 1.0 to 9.5 min.When the mass concentration was in the range of 0.05-0.50μg/ml,the linear relationship ofβ-receptor agonists was good,with correlation coefficients(r)≥0.9992.The detection limits of the method were in the range of 0.04-0.87μg/kg,and the quantitative limits were in the range of 0.35-1.86μg/kg.The average recovery values were in the range of 82.8%-108.9%,with RSDs(n=6)in the range of 1.9%-6.7%.[Conclusions]The method is simple,sensitive,reproducible,accurate,and can be used for simultaneous determination of the 14 kinds ofβ-receptor agonist residues in mutton.

Tandem Mass Tag-based proteomics analysis reveals the vital role of inflammation in traumatic brain injury in a mouse model

Proteomics is a powerful tool that can be used to elucidate the underlying mechanisms of diseases and identify new biomarkers.Therefore,it may also be helpful for understanding the detailed pathological mechanism of traumatic brain injury(TBI).In this study,we performed Tandem Mass Tag-based quantitative analysis of cortical proteome profiles in a mouse model of TBI.Our results showed that there were 302 differentially expressed proteins in TBI mice compared with normal mice 7 days after injury.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that these differentially expressed proteins were predominantly involved in inflammatory responses,including complement and coagulation cascades,as well as chemokine signaling pathways.Subsequent transcription factor analysis revealed that the inflammation-related transcription factors NF-κB1,RelA,IRF1,STAT1,and Spi1 play pivotal roles in the secondary injury that occurs after TBI,which further corroborates the functional enrichment for inflammatory factors.Our results suggest that inflammation-related proteins and inflammatory responses are promising targets for the treatment of TBI.

Spatiotemporal pharmacometabolomics based on ambient mass spectrometry imaging to evaluate the metabolism and hepatotoxicity of amiodarone in HepG2 spheroids

Three-dimensional(3D)cell spheroid models combined with mass spectrometry imaging(MSI)enables innovative investigation of in vivo-like biological processes under different physiological and pathological conditions.Herein,airflow-assisted desorption electrospray ionization-MSI(AFADESI-MSI)was coupled with 3D HepG2 spheroids to assess the metabolism and hepatotoxicity of amiodarone(AMI).High-coverage imaging of>1100 endogenous metabolites in hepatocyte spheroids was achieved using AFADESI-MSI.Following AMI treatment at different times,15 metabolites of AMI involved in Ndesethylation,hydroxylation,deiodination,and desaturation metabolic reactions were identified,and according to their spatiotemporal dynamics features,the metabolic pathways of AMI were proposed.Subsequently,the temporal and spatial changes in metabolic disturbance within spheroids caused by drug exposure were obtained via metabolomic analysis.The main dysregulated metabolic pathways included arachidonic acid and glycerophospholipid metabolism,providing considerable evidence for the mechanism of AMI hepatotoxicity.In addition,a biomarker group of eight fatty acids was selected that provided improved indication of cell viability and could characterize the hepatotoxicity of AMI.The combination of AFADESI-MSI and HepG2 spheroids can simultaneously obtain spatiotemporal information for drugs,drug metabolites,and endogenous metabolites after AMI treatment,providing an effective tool for in vitro drug hepatotoxicity evaluation.

Evaluation of allergenic protein profiles in three Chinese high-oleic acid peanut cultivars using NanoLC-Orbitrap mass spectrometry

High oleic-acid peanuts are known for their pre-longed shelf-life and health benefit due to high content of oleic fatty acid.However,the allergenicity and allergenic protein profiles in Chinese high-oleic peanuts have yet to be studied.For this purpose,an Orbitrap Fusion mass spectrometry(MS)-based method that is feasible for identification of putative allergenic protein as well as semi-quantitation of five major allergen protein in three different Chinese high-oleic peanut cultivars(JH 13,JH 16 and JH 18)have been reported.Results show that three Chinese high-oleic acid peanut cultivars selected all contained highly allergenic proteins Ara h1,Ara h 2,Ara h 3 and Ara h 6.The allergenic protein profiles of Chinese high-oleic acid peanut cultivars were very similar to that of conventional peanuts,but the allergenic protein subunits varied greatly among higholeic peanuts.Additionally,a comprehensive peptide-filtering pipeline had been developed for identification of potential peptide markers in peanut allergen proteins.Through the peptide-filtering pipeline,three novel peptide markers,IVQIEAKPNTLVLPK,SSNPDIYNPQAGSLR and AQSENYEYLAFK surrogate to Ara h 1,Ara h 3 with high abundance,good MS response and highly reliability were identified,which can be used as candidate peptide markers for the detection of peanut allergens in different food matrices.

Analysis of Norditerpenoid Alkaloids Extracted from Aconitum sinomantanum Nakai by Electrospray Ionization Tandem Mass Spectrometry

Electrospray ionization mass spectrometry（ESI-MS） was applied simultaneously in determining norditerpenoid alkaloids from the roots of Aconitum sinomantanum Nakai （RAS） based on molecular mass information. The tandem mass spectra（ ESI-MS^n） provided the alkaloidal structural information, through which the existence of these alkaloids was further confirmed. Accordingly, six known norditerpenoid alkaloids were simultaneously determined on the basis of their ESI-MS^n spectra. Furthermore, based on the diagnostic fragmentation pathways of alkaloidal MS^n, a rapid method for direct detection and characterization of alkaloids from an ethanolic extract of RAS was described.

Determination of urine catecholamines and metanephrines by reversed-phase liquid chromatography-tandem mass spectrometry

The measurement of urine catecholamine and metanephrine concentrations is important for biochemical screening and diagnosis of pheochromocytoma.The goal of this work was to develop a simple liquid chromatography-tandem mass spectrometry(LC-MS/MS)method for determining catecholamines and metanephrines in urine to replace an existing liquid chromatographic method using electrochemical detection.Urine samples were prepared using Oasis weak-cation-exchange cartridges.The eluate was analyzed on an Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column in 3 min.Adrenaline,noradrenaline,dopamine,metanephrine,normetanephrine,and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring(MRM).No evidence of ion suppression was observed.The assay was linear up to 5μmol/L for adrenaline,5μmol/L for noradrenaline,6.1μmol/L for dopamine,5.6μmol/L for metanephrine,and 34.6μmol/L for normetanephrine,with lower limits of quantification of 5,5,12,6 and 7nmol/L,respectively.The intra-day and inter-day precisions for all analytes ranged from 0.59%to 4.64%and1.98%to 4.80%,respectively.External quality assurance samples were assayed and showed excellent agreement with the target values.This simple method provides an improved assay for determining urine catecholamines and metanephrines.

Liquid Chromatography-tandem Mass Spectrometry for Analysis of Acylcarnitines in Dried Blood Specimens Collected at Autopsy from Neonatal Intensive Care Unit

Objective To investigate the feasibility of analyzing acylcarnitine in dry filter-paper blood spots by liquid chromatography-tandem mass spectrometry(LC-MS/MS) which could be applied to detect inborn errors of metabolism in neonates.Methods We obtained filter-paper blood from 26 dead infants from a neonatal intensive care unit(NICU) between October 1,2008 and September 30,2009.Acylcarnitine and amino acid profiles were obtained with LC-MS/MS.Four infants underwent routine autopsy.The postmortem blood specimens were compared with newborn blood specimens,and with specimens obtained from older infants with metabolic disorders.Results Of all the 26 patients,5(19.2%) were diagnosed as having different kinds of diseases:3 with methylmalonic acidemia(the concentration of C3,and the ratio of C3/C16,C3/C2 increased),1 with maple syrup urine disease(the concentration of leucine and isoleucine increased),and 1 with isovaleric aci-demia(the concentration of C5 increased).Conclusions Postmortem metabolic test can explain infant deaths and provide estimates of deaths attributable to inborn errors of metabolism in NICU.LC-MS/MS is suitable for analysis of postmortem specimens and can be considered for routine application in NICU autopsy.

Detection of 36 antibiotics in coastal waters using high performance liquid chromatography-tandem mass spectrometry

Among pharmaceuticals and personal care products released into the aquatic environment, antibiotics are of particular concern, because of their ubiquity and health effects. Although scientists have recently paid more attention to the threat of antibiotics to coastal ecosystems, researchers have often focused on relatively few antibiotics, because of the absence of suitable analytical methods. We have therefore developed a method for the rapid detection of 36 antibiotic residues in coastal waters, including tetracyclines （TCs）, sulfanilamides （SAs）, and quinolones （QLs）. The method consists of solid-phase extraction （SPE） and liquid chromatography-tandem mass spectrometry （LC-MS/MS） analysis, using electrospray ionization （ESI） in positive mode. The SPE was performed with Oasis HLB and Oasis MCX cartridges. Chromatographic separation on a Cr8 column was achieved using a binary eluent containing methanol and water with 0.1% formic acid. Typical recoveries of the analytes ranged from 67.4% to 109.3% at a fortification level of 100 ng/L. The precision of the method, calculated as relative standard deviation （RSD）, was below 14.6% for all the compounds. The limits of detection （LODs） varied from 0.45 pg to 7.97 pg. The method was applied to detemaine the target analytes in coastal waters of the Yellow Sea in Liaoning, China. Among the tested antibiotics, 31 were found in coastal ＇waters, with their concentrations between the LOD and 212.5 ng/L. These data indicate that this method is valid for analysis of antibiotics in coastal waters. The study first reports such a large number of antibiotics along the Yellow Sea coast of Liaoning, and should facilitate future comprehensive evaluation of antibiotics in coastal ecosystems

Development of an analytical method for multi-residue quantification of 18 anthelmintics in various animal-based food products using liquid chromatography-tandem mass spectrometry

In this study,we developed a simple screening procedure for the determination of 18 anthelmintics(including benzimidazoles,macrocyclic lactones,salicylanilides,substituted phenols,tetrahydropyrimidines,and imidazothiazoles)in five animal-derived food matrices(chicken muscle,pork,beef,milk,and egg)using liquid chromatography-tandem mass spectrometry.Analytes were extracted using acetonitrile/1% acetic acid(milk and egg)and acetonitrile/1% acetic acid with 0.5 mL of distilled water(chicken muscle,pork,and beef),and purified using saturated n-hexane/acetonitrile.A reversed-phase analytical column and a mobile phase consisting of(A)10 mM ammonium formate in distilled water and(B)methanol were used to achieve optimal chromatographic separation.Matrix-matched standard calibration curves(R^(2)≥0.9752)were obtained for concentration equivalent to ×1/2,×1,×2,×3,×4,and×5 fold the maximum residue limit(MRL)stipulated by the Korean Ministry of Food and Drug Safety.Recoveries of 61.2e118.4%,with relative standard deviations(RSDs)of ≤19.9%(intraday and interday),were obtained for each sample at three spiking concentrations(×1/2,×1,and ×2 the MRL values).Limits of detection,limits of quantification,and matrix effects were 0.02e5.5 mg/kg,0.06e10 mg/kg,and -98.8 to 13.9%(at 20 μg/kg),respectively.In five samples of each food matrix(chicken muscle,pork,beef,milk,and egg)purchased from large retailers in Seoul that were tested,none of the target analytes were detected.It has therefore been shown that this protocol is adaptable,accurate,and precise for the quantification of anthelmintic residues in foods of animal origin.

Liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry for Simultaneous Determination of Metformin and Glimepiride in Beagle Dog Plasma and Bioequivalence Study

A sensitive and selective liquid chromatography-electrospray ionization tandem mass spectrometry（LC- ES1-MS/MS） was used for the simultaneous determination of metformin and glimepiride in beagle dog plasma with glipizide as internal standard（IS）. After simplified protein precipitation with methanol, both the analytes and IS were chromatographed on a Zorbax CN column via gradient elution with methanol（containing 5 mmol/L ammonium ace- tate） and 5 mmol/L aqueous ammonium acetate as the mobile phase. Detection was performed by multiple reaction monitoring（MRM） scanning via ESI source operated in positive ionization mode. Specificity, linearity, accuracy, pre- cision, recovery, matrix effect and stability were validated for metformin and glimepiride in beagle dog plasma. The calibration curves were linear in a concentration range of 10-10000 ng/mL for metformin and 4-4000 ng/mL for glimepiride with both correlation coefficients higher than 0.99. The recoveries obtained for the analytes and IS were all between 82.7% and 101.2%. The method exhibited excellent performance in terms of selectivity, robustness, short analytical time and simplicity of sample preparation. Finally, the proposed method was applied to a bioequivalence study of self-made bilayer tablet and commercial formulation containing 500 mg of metformin and 1 mg of glimepi- ride in beagle dogs.

Liquid chromatography tandem mass spectrometry method for the estimation of lamotrigine in human plasma:Application to a pharmacokinetic study

A reliable,selective and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of lamotrigine in human plasma using lamotrigine13C3,d3 as an internal standard.Analyte and internal standard were extracted from human plasma by solid-phase extraction and detected in positive ion mode by tandem mass spectrometry with electrospray ionization（ESI） interface.Chromatographic separation was performed on a Chromolith s SpeedROD;RP-18e column（50-4.6 mm i.d.） using acetonitrile：570.1 mM ammonium formate solution（90：10,v/v） as the mobile phase at a flow rate of 0.500 mL/min.The calibration curves were linear over the range of 5.02-1226.47 ng/mL with the lower limit of quantitation validated at 5.02 ng/mL.The analytes were found stable in human plasma through three freeze（-20℃）-thaw（ice-cold water bath） cycles and under storage on bench-top in ice-cold water bath for at least 6.8 h,and also in the mobile phase at 10℃ for at least 57h.The method has shown good reproducibility,as the intra-and inter-day precisions were within 3.0%,while the accuracies were within 76.0% of nominal values.The validated LC-MS/MS method was applied for the evaluation of pharmacokinetic and bioequivalence parameters of lamotrigine after an oral administration of 50mg lamotrigine tablet to thirty-two healthy adult male volunteers.

Determination of Sex Hormones in Antler Velvet by High Performance Liquid Chromatography Tandem Mass Spectrometry

Eighteen sex hormones in antler velvet were determined by high performance liquid chromatography tandem mass spectrometry.The solid phase extraction was applied to eliminating the matrix effect.The experimental conditions were examined and optimized.Under the optimal conditions,the proposed method provides the good linearities and determination limits（0.2―1.0 μg/kg） of the analytes investigated.The recoveries ranging from 72.3% to 149.5% were obtained for the target analytes at two concentration levels.This method was applied to the determination of eighteen sex hormones in different kinds of antler velvet samples and the obtained results are satisfactory.The results indicate that the proposed method is suitable for the determination of sex hormones in antler velvet samples.

Rapid analysis of fifteen sulfonamide residues in pork and fish samples by automated on-line solid phase extraction coupled to liquid chromatography–tandem mass spectrometry

The aim of this work was to develop an automated on-line solid phase extraction(SPE)with liquid chromatography-tandem mass spectrometry method for the detection of fifteen sulfonamides in pork and fish samples.Samples were extracted with 0.2%formic acid acetonitrile solution,purified by on-line SPE device with HLB column,then separated by XBridge C18 column,using 0.1%formic acid solution and acetonitrile as the mobile phase.Mass spectrometric data was acquired under multiple reaction monitoring(MRM)mode using positive ionization electrospray.Internal standard method was used in the quantification,good linear relationship was got in range of 0.1–100 ng/mL and correlation coefficient was higher than 0.9990.The limits of detection were in the range of 0.125–2.00g/kg and the limits of quantitation were in the range of 0.250–5.00g/kg.Recoveries of the method were in range of 78.3%–99.3%,relative standard deviation were lower than 10%.The method was simple,sensitivity,and could be used for routine supervision and analysis of fifteen sulfonamides in pork and fish.