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.

Mass Spectrometry-based Deep Coverage Proteome:Evaluation of Cellular Protein Extraction Methods

The current study comprehensively evaluates four different protein extraction methods based on urea,sodium dodecyl sulfate(SDS),anionic surfactants(BT),and total RNA extractor(Trizol),aiming to optimize the sample preparation workflow for mass spectrometry-based proteomics.Using HeLa cells as an example,we found that the method employing the mass spectrometry-compatible surfactant BT reagent significantly reduces the total time consumed for protein extraction and minimizes protein losses during the sample preparation process.Further integrating the four protein extraction methods,we identified over 7000 proteins from HeLa cells without relying on pre-fractionation techniques,and 2990 of them were quantified using label-free quantification.It is worth noting that the BT and SDS methods demonstrate higher efficiency in extracting membrane proteins,while the Urea and Trizol methods are more effective in extracting proteins from nuclear and cytoplasmic fractions.In summary,this study provides a novel solution for deep proteome coverage,particularly in the context of cellular protein extraction,by integrating mass spectrometry-compatible surfactants with traditional extraction methods to effectively enhance protein identification numbers.

Bacterial Protein Profiling——Comparison of Three Mass Spectrometry Methodologies

Profiling the protein composition of bacteria is essential for understanding their biology,physiology and interaction with environment.Mass spectrometry has become a pivotal tool for protein analysis,facilitating the examination of expression levels,molecular masses and structural modifications.In this study,we compared the performance of three widely-used mass spectrometry methods,i.e.,matrix-assisted laser desorption/ionization(MALDI)protein fingerprinting,top-down proteomics and bottom-up proteomics,in the profiling of bacterial protein composition.It was revealed that bottom-up proteomics provided the highest protein coverage and exhibited the greatest protein profile overlap between bacterial species.In contrast,MALDI protein fingerprinting demonstrated superior detection reproducibility and effectiveness in distinguishing between bacterial species.Although top-down proteomics identified fewer proteins than bottom-up approach,it complemented MALDI fingerprinting in the discovery of bacterial protein markers,both favoring abundant,stable,and hydrophilic bacterial ribosomal proteins.This study represents the most systematic and comprehensive comparison of mass spectrometry-based protein profiling methodologies to date.It provides valuable guidelines for the selection of appropriate profiling strategies for specific analytical purposes.This will facilitate studies across various fields,including infection diagnosis,antimicrobial resistance detection and pharmaceutical target discovery.

Dual mass spectrometry imaging and spatial metabolomics to investigate the metabolism and nephrotoxicity of nitidine chloride

Evaluating toxicity and decoding the underlying mechanisms of active compounds are crucial for drug development.In this study,we present an innovative,integrated approach that combines air flowassisted desorption electrospray ionization mass spectrometry imaging(AFADESI-MSI),time-of-flight secondary ion mass spectrometry(ToF-SIMS),and spatial metabolomics to comprehensively investigate the nephrotoxicity and underlying mechanisms of nitidine chloride(NC),a promising anti-tumor drug candidate.Our quantitive AFADESI-MSI analysis unveiled the region specific of accumulation of NC in the kidney,particularly within the inner cortex(IC)region,following single and repeated dose of NC.High spatial resolution ToF-SIMS analysis further allowed us to precisely map the localization of NC within the renal tubule.Employing spatial metabolomics based on AFADESI-MSI,we identified over 70 discriminating endogenous metabolites associated with chronic NC exposure.These findings suggest the renal tubule as the primary target of NC toxicity and implicate renal transporters(organic cation transporters,multidrug and toxin extrusion,and organic cation transporter 2(OCT2)),metabolic enzymes(protein arginine N-methyltransferase(PRMT)and nitric oxide synthase),mitochondria,oxidative stress,and inflammation in NC-induced nephrotoxicity.This study offers novel insights into NC-induced renal damage,representing a crucial step towards devising strategies to mitigate renal damage caused by this compound.

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 13 preservatives in cosmetics by high performance liquid chromatography and verification by mass spectrometry

A method using high performance liquid chromatography(HPLC)was developed for the s imultaneous determination of 13 preservatives(levulinic acid,p-hydroxyacetophenone,raspberry ketone,p-anisic acid,caprylhydroxamic acid,hydroxyethoxyphenyl butanone,methylisothiazolinone,phenoxyethanol,b e n z oic acid,methylparaben,chlorphenesin,dehydroacetic acid,and 5-bromo-5-nitro-1,3-dioxane)in cosmetics.Different types of samples were ultrasonically extracted by methanol,then the separation of 13 preservatives was carried out on a column of Agilent ZORBAX Eclipse XDB-C18(250 mm×4.6 mm,5μm)by gradient elution at a flow rate of 1.0 mL/min,using 0.1%phosphoric acid solution and acetonitrile as mobile phases.The column temperature was 30℃,and the detection was completed by a diode array detector with the wavelengths at 275,230 and 210 nm.Suspected positive samples were further confirmed by liquid chromatography-tandem mass spectrometry or gas chromatography-mass spectrometry.The linear regression analysis data shows good linearity for 13 preservatives in the respective mass concentration range,with their correlation coefficients(r)greater than 0.9998.The limits of detection(LODs)and limits of quantitation(LOQs)of the method are in the ranges of 0.4-100.0 mg/kg and 1.2-250.0 mg/kg,respectively.At three spiked levels,the average recoveries for 13 target compounds in three kinds of matrix samples are within 84.0%-115.4%,and the relative standard deviations(RSD)are within 0.5%-4.8%(n=6).This method is convenient,efficient,and precise,which can be used for qualitative and quantitative analysis of common preservatives in daily cosmetics.

Improved isochronous mass spectrometry with tune measurement

In conventional isochronous mass spectrometry(IMS)performed on a storage ring,the precision of mass measurements for short-lived nuclei depends on the accurate determination of the revolution times(T)of stored ions.However,the resolution of T inevitably deteriorates due to the magnetic rigidity spread of the ions,limiting the mass-resolving power.In this study,we used the betatron tunes Q(the number of betatron oscillations per revolution)of the ions and established a correlation between T and Q.From this correlation,T was transformed to correspond to a fixed Q with higher resolution.Using these transformed T values,the masses of ^(63)Ge,^(65)As,^(67)Se,and ^(71)Kr agreed well with the mass values measured using the newly developed IMS(Bρ-IMS).We also studied the systematics of Coulomb displacement energies(CDEs)and found that anomalous staggering in CDEs was eliminated using new mass values.This method of T transformation is highly effective for conventional IMS equipped with a single time-of-flight detector.

^(13)C NMR、FT-IR、Raman和建模技术对烟煤和无烟煤分子结构的应用研究

【目的】探究高精度煤的结构演化及其机理的定量表征。【方法】通过显微组分鉴定、镜质体反射率、工业品质、元素分析和光谱分析,确定了烟煤(FS1)和无烟煤(ZY1)碳骨架结构、官能团的赋存状态等信息,并通过计算机辅助分子设计建立2个分子结构模型。【结果】结果表明,随着煤化作用的进行,烟煤到无烟煤过程中,亚甲基的损失速率比甲基的损失速率快,芳香性增强,芳香环的脂肪族链变短且支化度较高,含氧官能团逐渐减少,煤结晶程度增强,煤的化学结构趋于成熟稳定,且煤中的脂肪碳减少,芳香碳增加,甲基碳和亚甲基碳含量减少。经过多次尝试确定了芳香炭、脂肪族侧链和氧官能团之间的键合模式,获得最终的分子结构模型:C_(175)H_(162)O_(13)N_(2)(FS1)、C_(190)H_(159)O_(5)N_(3)(ZY1).该模型较好地反映煤的真实结构,模拟的^(13)C NMR光谱与实验光谱具有良好的一致性。上述研究为不同变质程度煤的分子结构演化提供了理论参考,为建立高可信度的分子结构表征提供了方法。

Mapping conformational changes on bispecific antigen-binding biotherapeutic by covalent labeling and mass spectrometry

Biotherapeutic's higher order structure(HOS)is a critical determinant of its functional properties and conformational relevance.Here,we evaluated two covalent labeling methods:diethylpyrocarbonate(DEPC)-labeling and fast photooxidation of proteins(FPOP),in conjunction with mass spectrometry(MS),to investigate structural modifications for the new class of immuno-oncological therapy known as bispecific antigen-binding biotherapeutics(BABB).The evaluated techniques unveiled subtle structural changes occurring at the amino acid residue level within the antigen-binding domain under both native and thermal stress conditions,which cannot be detected by conventional biophysical techniques,e.g.,near-ultraviolet circular dichroism(NUV-CD).The determined variations in labeling uptake under native and stress conditions,corroborated by binding assays,shed light on the binding effect,and highlighted the potential of covalent-labeling methods to effectively monitor conformational changes that ultimately influence the product quality.Our study provides a foundation for implementing the developed techniques in elucidating the inherent structural characteristics of novel therapeutics and their conformational stability.

Determination of 14 Organophosphorus Pesticide Residues in Mutton by Gel Permeation Chromatography-Gas Chromatography-Mass Spectrometry(GPC-GC-MS)

[Objectives]This study was conducted to purify mutton samples by gel permeation chromatography(GPC).[Methods]Fourteen organophosphorus pesticide residues in samples were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry(GC-MS)in selective ion scanning mode(SIM).[Results]The organophosphorus pesticide standard solutions showed good linearity in the mass concentration range of 0.1-10.0μg/ml with correlation coefficients(r)not lower than 0.999,and the detection limits(S=3 N)ranged from 0.01 to 0.05 mg/kg.The average recovery values were in the range of 80.2%-99.7%,with relative standard deviations(RSDs,n=3)in the range of 1.8%-6.3%,at the addition levels of 0.5,1.0 and 2.0 mg/kg.[Conclusions]The method is simple,sensitive and accurate,and can be used for the determination of organophosphorus pesticide residues in mutton.

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.

Chemical profiling of bioactive compounds in the methanolic extract of wild leaf and callus of Vitex negundo using gas chromatographymass spectrometry

BACKGROUND The investigation of plant-based therapeutic agents in medicinal plants has revealed their presence in the extracts and provides the vision to formulate novel techniques for drug therapy.Vitex negundo(V.negundo),a perennial herb belonging to the Varbanaceae family,is extensively used in conventional medication.AIM To determine the existence of therapeutic components in leaf and callus extracts from wild V.negundo plants using gas chromatography-mass spectrometry(GCMS).METHODS In this study,we conducted GC-MS on wild plant leaf extracts and correlated the presence of constituents with those in callus extracts.Various growth regulators such as 6-benzylaminopurine(BAP),2,4-dichlorophenoxyacetic acid(2,4-D),α-naphthylacetic acid(NAA),and di-phenylurea(DPU)were added to plant leaves and in-vitro callus and grown on MS medium.RESULTS The results clearly indicated that the addition of BAP(2.0 mg/L),2,4-D(0.2 mg/mL),DPU(2.0 mg/L)and 2,4-D(0.2 mg/mL)in MS medium resulted in rapid callus development.The plant profile of Vitex extracts by GC-MS analysis showed that 24,10,and 14 bioactive constituents were detected in the methanolic extract of leaf,green callus and the methanolic extract of white loose callus,respectively.CONCLUSION Octadecadienoic acid,hexadecanoic acid and methyl ester were the major constituents in the leaf and callus methanolic extract.Octadecadienoic acid was the most common constituent in all samples.The maximum concentration of octadecadienoic acid in leaves,green callus and white loose callus was 21.93%,47.79%and 40.38%,respectively.These findings demonstrate that the concentration of octadecadienoic acid doubles in-vitro compared to in-vivo.In addition to octadecadienoic acid;butyric acid,benzene,1-methoxy-4-(1-propenyl),dospan,tridecanedialdehyde,methylcyclohexenylbutanol,chlorpyrifos,n-secondary terpene diester,anflunine and other important active compounds were also detected.All these components were only available in callus formed in-vitro.This study showed that the callus contained additional botanical characteristics compared with wild plants.Due to the presence of numerous bioactive compounds,the medical use of Vitex for various diseases has been accepted and the plant is considered an important source of therapeutics for research and development.

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.

三七治疗骨关节炎机制:基于UHPLC-QE-MS、网络药理学及分子动力学模拟

背景:课题组前期研究发现三七能够修复骨细胞的形态结构,对于治疗骨关节炎具有良好的应用前景,但目前对于三七的具体作用机制尚不清楚。目的:采用超高效液相色谱-四极杆-静电场轨道阱串联质谱(ultra-high performance liquid chromatography-Q exactive-mass spectrometry,UHPLC-QE-MS)技术鉴定三七的主要成分,并结合网络药理学、分子对接和分子动力学模拟探究三七治疗骨关节炎的作用机制。方法:利用UHPLC-QE-MS技术鉴定三七的主要成分后,运用TCMSP数据库筛选活性成分,通过TCMSP和Uniprot数据库查找活性成分靶点,通过疾病数据库筛选骨关节炎靶点。在药物靶点与疾病靶点取交集后,导入STRING数据库和Cytoscape软件构建蛋白互作网络筛选关键靶点,通过“活性成分-作用靶点”网络筛选关键活性成分。再对关键靶点进行富集分析,并对关键活性成分和关键靶点进行分子对接验证,最后选取结合能最低的结果进行分子动力学模拟。结果与结论:①在三七溶液中共鉴定出57种活性成分,成分靶点与疾病靶点交集50个,关键活性成分5个(槲皮素、熊脱氧胆酸、山奈酚、柚皮素和红藻氨酸),关键靶点5个(白细胞介素6、基质金属蛋白酶9、白细胞介素1β、白蛋白和趋化因子配体2);②基因本体功能富集642个条目,其中620个条目代表生物过程,21个条目代表分子功能,1个条目代表细胞成分;京都基因与基因组百科全书通路分析63条通路,主要涉及雌激素信号通路、白细胞介素17信号通路和高糖基化终末产物-高糖基化终末产物受体信号通路;③分子对接显示关键活性成分和关键靶点结合活性良好,分子动力学模拟提示槲皮素和基质金属蛋白酶9间的相互作用稳定;④对三七成分进行了较全面研究,初步阐明了其药效物质基础,预测三七可通过多组分、多靶点、多途径和多通路发挥抗炎、软骨保护和免疫调节作用来治疗骨关节炎。

木材炭化机理的FT-IR光谱分析研究

结合炭化物的性质,采用傅立叶变换红外光谱,对木材炭化过程中碳网构造、表面官能团变化情况进行分析,揭示了其演变规律.结果表明:FT-IR光谱中1600cm-1附近芳环振动吸收强度的变化和波数的位移、3100～3200cm-1间v(Ar-H)及900～650 cm-1间v(Ar-H)的吸收强度的变化,与炭化过程中碳网构造的变化是相对应的.随炭化温度升高,炭化物聚合度升高,表面官能团也发生了明显变化.600～700℃间,炭化物中发生了大量-OH的脱水反应,碳网构造开始迅速发达.700℃之后,碳网的平面有序化并进一步生长.慢速升温有利于形成结构更规整的平面碳网,炭化物的表面官能团更少.

东胜长焰煤热解含氧官能团结构演化的^(13)C-NMR和FT-IR分析

以东胜煤田色拉一号井田2号煤层长焰煤为研究对象,利用浮沉离心法富集其镜质组。基于工业分析、元素分析、13C-NMR、FT-IR、谱图分峰拟合技术和化学分析测试,求取镜煤及一系列热解煤含氧官能团结构与含量参数,从不同角度研究了含氧官能团的分布规律与演化特点。镜煤中羧基、羰基含量分别为8.91~10.90 mol/kg、1.61~1.79 mol/kg,随热解温度升高羧基显著减少。热解作用促使以端基形式连接在脂肪链或脂肪环结构氧上的甲基和亚甲基首先脱去,且在温度高于350℃后基本稳定。氧在热解过程赋存状态的变化是芳香体系与脂肪体系相互竞争的结果,510℃热解煤中芳香类氧和脂肪类氧的含量分别为7.49、3.45 mol/kg。羟基的演化过程与热解过程中氧的赋存状态密切相关。随着热解过程的进行,在热解温度低于440℃时,各种羟基含量均减少,热解过程对于大分子网络的破坏干扰了各种氢键作用,而羟基π作用则暂时增强,至510℃时各种氢键含量均降为最低。东胜长焰煤中含氧官能团化学活性顺序为:[COOH]>[R-O]>[Ar-O-Ar,Ar-O-C,C-O-C]>[C=O]。镜煤非活性醚键含量为0.68 mol/kg,活性醚键为0.48 mol/kg,主要为非活性醚键。

FT-IR法研究聚氨酯的固化行为

用 FT- IR研究了 TDI- PPG- MOCA体系的固化动力学 ,得到了不同温度下固化反应速度、反应程度与固化时间的关系及反应的活化能。讨论了固化剂用量、温度对固化动力学参数、交联反应的影响。结果表明 ,固化剂的用量、温度对固化动力学参数、交联反应有较大影响 。

Determination on Heavy Metals Content of Achyranthes bidentata Blume. through Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

[Objective] The inductively coupled plasma mass spectrometry(ICP-MS)was constructed to determine the contents of lead,cadmium,mercury and arsenic in Archyranthes bidentata Blume.[Method]Under the optimum operation condition of ICP-MS,the samples were digested by microwave.The element 114In was taken as an internal standard element to compensate body effect and ICP-MS method was used to determine the contents of lead,cadmium,mercury and arsenic.[Result]For the determined elements,the correlation coefficient(r)of standard curve was over 0.9995 and recovery rate was from 96.7% to 106.4% while RSD was less than 11.2%.The result of determination showed that the heavy metal content in Archyranthes bidentata Blume.beyond standard was serious.[Conclusion]The constructed ICP-MS method with simple operation,rapid response,accuracy and high sensitivity in this experiment could be used for quality control of Chinese medicinal materials by detecting heavy metal contents in different Chinese medicinal materials from original places.

不同类型的CO_3^(2-)替换羟基磷灰石固溶体晶体化学FT-IR研究

利用FT-IR结合XRD对不同类型的CO32-替换磷灰石固溶体进行了晶体化学研究,结果表明:B型替换碳羟磷灰石(CHAP)的替换方式是犤CO3·OH犦四面体替换犤PO4犦四面体;A型替换CHAP的替换方式是犤CO3犦三角形配位体替换通道位置的OH-;AB混合型替换CHAP的FT-IR谱中非对称伸缩振动ν3分裂为ν3-1、ν3F、ν3-4,高斯函数法拟合表明ν3F峰是A型替换的ν3-2与B型替换的ν3-3的叠合。当WCO2-33.34%时,随CO32-含量增加,A型替换量增大,替换指数(SI)增大,且当WCO2-3=3.34%时,SI达最大值,当3.34%<WCO2-37.52%时,随CO32-含量增加,SI减小,B型替换量增大,且当WCO2-3=7.52%时总固溶量饱和。

纸浆ECF和TCF漂白过程中纤维形态变化和FT-IR分析

通过SEM观察发现,未漂竹浆抄成的纸张,暴露于表面的长纤维较少,纤维形状扁平,纤维之间空隙很少。经氧脱木素后,纸张表面细小纤维减少,纤维间空隙较多,而经二氧化氯漂白后,纸张表面保留了一部分形态扁平的纤维,纤维间空隙相对较少;未漂浆纤维较粗,纤维表面光滑,结构密实,而经氧脱木素后,纤维变细,纤维表面轻微帚化,结构较疏松。浆料经CEH漂白后纤维受到较大程度的破坏,而经OQP和DQP漂白后,纤维也受到一定程度的破坏,但相对较小,两者相比较,DQP漂白浆的纤维完整性保持较好。FT-IR分析表明,随着漂白的进行,木素结构中苯环的特征峰逐渐减弱以至消失,羰基等发色基团也逐步减少,纸浆白度提高。