高分辨电感耦合等离子体质谱法测定高纯镍中25种痕量元素

镍基高温合金广泛应用于航空发动机的热端部件,其主要原材料高纯镍的纯度对其性能有着重要影响,因此需要测定和控制高纯镍中痕量元素的含量。通过选择合适的同位素克服质谱干扰,选择标准加入法绘制校准曲线克服基体效应,对辅助气流量进行了优化,在高分辨率模式下测定钙和砷,在中分辨率模式下测定其余元素,建立了高分辨电感耦合等离子体质谱法测定高纯镍中镁、铝、磷、钙、锰、铁、铜、锌、镓、锗、砷、硒、银、镉、铟、锡、锑、碲、金、汞、铊、铅、铋、钍、铀共25种痕量元素的方法。在优化的实验条件下,校准曲线线性相关系数均在0.999以上,各元素的方法检出限在0.003～0.15 μg/L之间,定量限在0.010～0.50 μg/L之间。选择3个高纯镍样品(纯度为99.99%),按实验方法对其中25种痕量元素进行测定,同时对同一高纯镍样品进行不同梯度的加标回收试验,结果表明,测定结果的相对标准偏差(RSD,n=8)为3.5%~9.7%,回收率为90%～110%。采用实验方法测定纯镍标准物质,测定值与标准值基本一致。按照实验方法对高纯镍样品中25种杂质元素进行测定,同时采用辉光放电质谱法进行方法比对,结果表明,两种分析方法测定结果吻合度较高。     

Specific metal-oligonucleotide binding studied by high resolution tandem mass spectrometry

BACKGROUND: Benign reactive lymphoid hyperplasia is an uncommon uveal tumor. Misdiagnosis may lead to unnecessary enucleations. Clinical evaluation alone is usually not sufficient to diagnose this tumor. OBJECTIVE: To evaluate the utility of standardized echography in the recognition of this disease. METHODS: Retrospective review of the medical and echographic records of 6 patients with choroidal involvement of benign reactive lymphoid hyperplasia. RESULTS: Extraocular episcleral lymphoid nodules were present in 5 of the 6 patients and were usually seen as a late manifestation of the disease. Two patients had repeated echography after treatment of the tumor and showed marked regression of the episcleral nodules. CONCLUSIONS: A combination of clinical and echographic findings can assist in the accurate diagnosis of this rare uveal tumor. The presence of episcleral nodules on standardized echography supports the diagnosis.     

Accurate peptide sequencing by post-source decay matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Partial 18O-labeling of peptides has been applied to post-source decay experiments in a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. The ions which originate from the carboxyl terminus of a peptide partially retain 18O atoms which have readily been incorporated into the C-terminal carboxyl groups during enzymatic hydrolysis in a buffer containing 40 atom percent H218O. The isotopic resolution of singly charged precursor ions and their product ions obtained for peptides up to ca. 2800 Da has been achieved using the delayed extraction method, which permits the rapid identification and assignment of the 18O-labeled and non-labeled ion species in the PSD spectra. The results obtained from several 18O-labeled peptides, derived from an enzymatic digest, demonstrate the accuracy and reproducibility of the present method, which will be in widespread use for protein identification via database searching or for investigations of totally unknown proteins.     

高分辨电感耦合等离子体质谱法测定电池锌粉中杂质元素

应用高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定电池锌粉中Mg、Mn、Fe、Co、Ni、Cu、As、Mo、Cd、Sb、Pb、Bi 12种痕量元素。考察了试样消解时引入的氯离子、试样中基体锌和共存元素对被测元素的影响及其消除方法。结果表明,高浓度氯离子对Bi、Cd、Mn、Mg、Fe的信号产生抑制作用,但其浓度小于5%时影响较小,因此可以通过控制试液中氯离子浓度来减少氯离子的影响;基体锌和其他共存元素的质谱干扰可以根据被测元素选择不同的质谱分辨率来克服;基体锌的质量浓度达到100 mg/L时,所有被测元素均受基体效应影响,但可以通过选择合适的内标元素进行校正。Bi的检出限为0.003μg/L,Fe的检出限为0.25μg/L,其它10种痕量元素的检出限在0.012~0.074μg/L之间。方法用于电池锌粉12个微量元素的测定,测定结果与其他方法(ICP-AES、GF-AAS、HG-AAS)相符,加标回收率在94.0%~108.6%之间,相对标准偏差(RSD)小于4.2%。     

基体未分离高分辨电感耦合等离子体质谱法测定钢中痕量元素

为了满足钢铁产品日益严格的质量需求,将钢铁产品中痕量元素的测定下限降低至μg/g级也日显重要。本研究工作利用高分辨率的等离子质谱仪快速、准确测定了钢中μg/g级的B,Al,P,Cr,Pb,Sn,Sb,As,Bi等多种元素。钢铁样品用硝酸、盐酸、氢氟酸在电热板上加热或微波消解,溶液经稀释后未经基体分离,未加内标直接用电感耦合等离子体质谱法(ICP-MS)测定。该方法检测下限:P为0.145μg/g,其余元素低于0.1μg/g。精密度好,相对标准偏差(n=10):Bi为10·5%,其余元素小于5%。回收率:A     

Source identification of urban airborne polycyclic aromatic hydrocarbons by gas chromatographic mass spectrometry and high resolution mass spectrometry

Polycyclic aromatic hydrocarbons formed during the combustion of three common fuels (coal, wood and kerosene) were separated and identified by capillary-column gas chromatographic mass spectrometry and were compared to airborne polycyclic aromatic hydrocarbons from Indianapolis, a high coal consuming area, and Boston, a low coal consuming area. High resolution mass spectral data were utilized in the construction of alkyl homolog plots for the comparison of alkyl distribution within each sample.     

高分辨电感耦合等离子体质谱法测定纯铁和低合金钢中痕量磷

研究了用高分辨电感耦合等离子体质谱(HR-ICP-MS)法测定纯铁及低合金钢中痕量磷的方法。在优化的仪器条件下,采用基体匹配,并用Sc为内标对基体效应进行校正。由于磷存在较严重的15N16O,14N16O1H,12C18O1H等多原子离子干扰,利用仪器的高分辨性能,选择中分辨率扫描可消除这些离子对测定磷的影响。磷含量在0.000 2%~0.005 0%(w/%)范围内线性良好,相关系数为0.999 5。检测下限为0.000 08%。方法用于纯铁和低合金钢标准样品中磷的测定,结果同认定值相一致,相对标准偏差     

Peptide and protein identification by matrix-assisted laser desorption ionization (MALDI) and MALDI-post-source decay time-of-flight mass spectrometry

The potential of matrix-assisted laser desorption ionization (MALDI) and MALDI-post-source decay (PSD) time-of-flight mass spectrometry for the characterization of peptides and proteins is discussed. Recent instrumental developments provide for levels of sensitivity and accuracy that make these techniques major analytical tools for proteome analysis. New software developments employing protein database searches have greatly enhanced the fields of application of MALDI-PSD. Peptides and proteins can be easily identified even if only a partial sequence information is determined. Derivatization procedures have been optimized for MALDI-PSD to increase the structural information and to obtain a complete peptide sequence even in critical cases. They are fast, simple and can be performed on target. MALDI-PSD is also a very powerful tool to characterize or elucidate post-translational or chemically induced modifications. In association with database searches, proteins issued from electrophoretic gels can be identified after specific enzymatic cleavages and peptide mapping.     

Structural characterization of the cyanelle peptidoglycan of Cyanophora paradoxa by 252Cf plasma desorption mass spectrometry and fast atom bombardment/tandem mass spectrometry

A strategy for the structural characterization of the four major NaBH4-reduced peptidoglycan monomers derived from muramidase-digested peptidoglycan from the cyanelles of the flagellate Cyanophora paradoxa Korschikoff is described. Initial molecular weight determination of these glycopeptides was performed by positive and negative ion plasma desorption mass spectrometry. Due to the presence of two pairs of disaccharide tripeptide and disaccharide tetrapeptide monomers differing in mass by 112 units, respectively, an as yet unknown peptidoglycan modification either at the carbohydrate or at the peptide moiety was assumed. beta-Elimination of the disaccharide unit from the unreduced peptidoglycan monomers yielded the corresponding (modified) N1-lactyltripeptides and -tetrapeptides, respectively. These peptides, N-terminally blocked with lactic acid, unambiguously showed the modification to be located on the peptide moiety. By positive ion fast atom bombardment/hybrid tandem mass spectrometry of the reduced peptidoglycan monomers as well as of the corresponding deglycosylated monomers (= N1-lactylpeptides) the modification was determined to be linked to the glutamic acid moiety. Based on combined data from plasma desorption mass spectrometry, tandem mass spectrometry, accurate mass measurement and amino acid analysis of the acid hydrolysate after derivatization with o-phthaldialdehyde by high-performance liquid chromatography we could establish the structure of the modification as N-acetylputrescine. Finally, the confirmation of the linkage of the glutamic acid to diaminopimelic acid via the gamma-COOH was based on the presence of a-type peptide backbone fragment ions in the positive ion plasma desorption mass spectra of the modified N1-lactylpeptides.     

高分辨电感耦合等离子体质谱分析地质样品中痕量元素的应用进展

高分辨电感耦合等离子体质谱(HR-ICP-MS)是以电感耦合等离子体为离子源、以扇形磁场质谱为检测器的元素及同位素分析技术,具有灵敏度高、检出限低、多元素同时分析等优点.作为克服质谱干扰最简单、最有效的技术,HR-ICP-MS已被逐渐应用于地质、环境、冶金、生物等领域.文章对HR-ICP-MS的工作原理及技术特点进行了...     

Protein conformational changes determined by matrix-assisted laser desorption mass spectrometry

Caldesmon is an actin/calmodulin/tropomyosin protein located in the thin filaments of smooth muscle cells and microfilaments of nonmuscle cells. Two isoforms of caldesmon, h- and l-types, shown to exist in vertebrate smooth and nonmuscle cells respectively, are produced by alternative splicing of the caldesmon mRNA encoded by a single gene. To study the expression of smooth muscle specific h-caldesmon during the differentiation of mesenchymal cells into smooth muscle cells, soluble protein and total RNA from the gizzard primordium in the gut region of 5-day and gizzards of 7-, 9-, 13-, 17- and 21-day embryos and 2-days post-hatch chicks were extracted and analyzed for caldesmon expression at both protein and mRNA levels. Western blot analysis of proteins and immunofluorescence microscopy of tissue section were carried out using an antibody specific for h-caldesmon. Total RNA was analyzed by Northern blotting using a caldesmon cDNA probe, and h- and l-caldesmon cDNAs were identified due to the difference in their molecular sizes (4.8 and 4.1 kb respectively). The mRNA was also analyzed by reverse transcribed-polymerase chain reaction (RT-PCR) and Southern blot analysis. Our results show that the I-caldesmon mRNA was expressed at higher levels in the gizzard primordium during the early stages of development, and decreased gradually during growth. The h-caldesmon protein and mRNA, not expressed at day 5, is minimally expressed at day 7 and is fully turned on by day 9. Additionally, sequence analyses of the RT-PCR products of I-caldesmon showed that it lacked the spacer region, as predicted. RT-PCR analysis of total RNA gave two h-caldesmon fragments. These two fragments were identified as two different isoforms of h-caldesmon since they both contained the spacer region. They also showed homology in the region of exon 4 had differences in the region of exon 3b.     

电感耦合等离子体质谱法测定钢中痕量酸溶铝

采用硝酸溶解样品,建立了电感耦合等离子体质谱法(ICP-MS)测定钢中痕量酸溶铝(Als)的方法,并对其测定条件进行了优化。实验表明:采用纯化后硝酸溶解样品可以降低对检测结果的影响;高纯铁基体效应对测定的影响不可忽略,故采用待测样品作为基体的标准加入法绘制校准曲线以消除该影响;采用石英烧杯进行样品溶解,测定结果比玻璃烧杯更稳定;采用塑料容量瓶对硅钢标准样品溶液定容,测定结果相对于玻璃容量瓶更接近认定值;对样品前处理的条件进行了优化,最终选择硝酸用量为5mL,溶解时间为10min;选择⁴⁵Sc作为内标对硅钢标准样品进行测定,结果较选用⁸⁹Y为内标更接近认定值;采用2%(体积分数)硝酸冲洗管路8s,可基本消除记忆效应。以²⁷Al质量浓度为横坐标,²⁷Al与内标元素响应值的比值为纵坐标绘制标准加入法校准曲线,校准曲线方程的相关系数为0.9998;方法对样品的测定下限为0.00006%。采用实验方法对5个钢标准样品和2个合金钢实际样品进行测定,测定值与认定值基本一致,相对标准偏差(RSD,n=5)在1.6%~4.5%之间。     

Identification of pollutants in a municipal well using high resolution mass spectrometry

An elevated incidence of childhood cancer was observed near a contaminated site. Trace amounts of several isomeric compounds were detected by gas chromatography/mass spectrometry (GC/MS) in a concentrated extract of municipal well water. No matching library mass spectra were found and Fourier transform IR and NMR analyses were not feasible due to the low concentration of the compounds. Mass peak profiling from selected-ion-recording data (MPPSIRD) provided the sensitivity and scan speed necessary to acquire mass peak profiles at mass resolutions of 10,000 to 20,000 for the molecular ion (M+) and 10 fragment ions as capillary GC peaks eluted. Using a profile generation model (PGM), the elemental composition of the molecular ion was determined from the exact masses and abundances of the M, M + 1 and M + 2 profiles. Fragment ion compositions were determined from their exact masses based on the elements in the molecular ion. Exact mass differences between the molecular and fragment ions corresponded to unique combinations of atoms for the neutral losses. Consequent reduction of the number of possible structures for the fragment ions simplified mass spectral interpretation. After inspecting library mass spectra for smaller molecules, isomeric structures were hypothesized with cyano and alkylcyano groups attached to tetralin. A literature search found such isomers produced by an industrial polymer synthesis. Three isomers in a standard form polymerization of styrene and acrylonitrile provided the same mass spectra and GC retention times as isomers in the extract.     

微波消解-基体匹配高分辨电感耦合等离子体质谱法测定煤中钽铀镱

煤中Ta、U、Yb的测定对煤炭地球化学研究和产地溯源具有重要意义。在采用高分辨电感耦合等离子体质谱(HR-ICP-MS)测定煤中Ta、U、Yb时,基体效应较为严重,导致测定结果偏高。采用8 mL HNO₃-1 mL HF微波消解煤炭样品,优化了消解体系、消解程序、复溶时间等前处理条件,选用¹⁸¹Ta、²³⁸U、¹⁷²Yb为测定同位素,采用低分辨率模式测定U,高分辨率模式测定Ta、Yb,以Rh内标结合基体匹配法克服基体效应,实现了煤中Ta、U、Yb的HR-ICP-MS测定。在优化的实验条件下,在1.000~20.00 μg/L范围内,被测元素与内标元素信号强度的比值与被测元素质量浓度呈现良好的线性相关,相关系数不小于0.999 9,各元素的检出限在0.002~0.008 μg/g之间,定量限在0.007~0.027 μg/g之间。将实验方法应用于煤炭标准样品中Ta、U、Yb的测定,测定值与认定值基本一致,相对标准偏差(RSD,n=6)为2.3%~4.3%。选取俄罗斯其他烟煤及无烟煤、澳大利亚其他烟煤、蒙古炼焦煤、印度尼西亚褐煤及其他烟煤6个代表性样品,按照实验方法进行测定,测定结果表明,Ta、U在俄罗斯其他烟煤样品中含量最高,Yb在澳大利亚其他烟煤样品中含量最高,印度尼西亚褐煤中3种元素含量均最低。     

Characterisation of proteins from two-dimensional electrophoresis gels by matrix-assisted laser desorption mass spectrometry and amino acid compositional analysis

Amino acid compositional analysis and peptide mass fingerprinting by matrix assisted laser desorption mass spectrometry have been used to characterise proteins obtained from two-dimensional electrophoresis (2-DE) separations of human cardiac proteins. A group of twelve protein spots was selected for analysis. The identities of eight of the proteins had been determined by conventional protein characterisation methods, two were unknown proteins and two had putative identities from protein database spot comparison. Amino acid analysis and peptide mass fingerprinting gave corresponding identities for seven of the twelve proteins, which also agreed with our initial identifications. Three proteins which had been identified previously were not confirmed in this study and putative identities were obtained for the two unknown proteins. The advantages, problems and use of amino acid analysis and peptide mass fingerprinting for the analysis of proteins from 2-DE are discussed. The data highlight the need to use orthogonal techniques for the unequivocal identification of proteins from 2-DE gels.     

C-terminal peptide sequencing via multistage mass spectrometry

Results are presented showing the ability to obtain C-terminal sequence information from peptides by multiple stages of mass spectrometry. Under typical low-energy collision-induced dissociation conditions of quadrupole ion trap and ion cyclotron resonance mass spectrometers, lithium- and sodium-cationized peptides dissociate predominantly by reaction at the C-terminal peptide bond or an adjacent bond. For the majority of cases studied, the dominant reaction is a rearrangement process that results in the loss of the C-terminal residue and formation of a product ion that is one amino acid shorter than the original peptide ion. Using the multistage MS/MS capabilities of quadrupole ion trap and ion cyclotron resonance mass spectrometers, a subsequent stage of MS/MS can be performed to determine the identity of the new C-terminal residue. Up to eight stage of MS/MS have been performed with both quadrupole ion trap and ion cyclotron resonance mass spectrometers. In general, the same dissociation pathways are observed with both instruments, although occasionally there are significant differences in the branching ratios of competing pathways.     

乙二酸对电感耦合等离子体质谱的增强效应(英文)

研究了不同浓度下乙二酸对元素电感耦合等离子体质谱(ICP-MS)行为的影响。结果表明,低浓度乙二酸对所分析元素的灵敏度具有显著的增敏效应,尤其是对电离电位在9~11eV的Be,Zn,Se,As,Sb,Hg等高电离电位元素。作为一种增敏剂,乙二酸可以补偿由于无机基体的存在对高电离电位元素所产生的信号抑制现象,从而提高其分析灵敏度2~10倍。采用所建立的方法测定了水标准物质中的Be,Zn,Se,As,Sb和Hg,其测定结果与标准物质的认定值基本一致。     

电感耦合等离子体质谱法测定高纯锌中7种痕量元素

高纯锌中铁、铜、镉、锑、铅、锡、砷元素含量低,基体和多原子离子干扰严重,这使得溶样后直接采用电感耦合等离子体质谱法(ICP-MS)对这7种元素进行测定的难度较大。实验表明:采用15 mL硝酸(1+2)低温溶解0.100 0 g样品,不进行基体分离,通过优化仪器参数、选择合适的同位素避免质谱干扰,采用标准加入法绘制校准曲线消除基体效应,可实现电感耦合等离子体质谱法(ICP-MS)对高纯锌中铁、铜、镉、锑、铅、锡和砷共7种痕量元素的测定。各元素校准曲线的相关系数在0.995 8到0.999 7之间,方法检出限为0.05~7.53 μg/L。采用实验方法对高纯锌实际样品中铁、铜、镉、锑、铅、锡和砷进行分析,测得结果的相对标准偏差(RSD,n=11)为2.4%~5.3%,加标回收率为96%~109%。按照实验方法测定纯锌样品中7种痕量元素,砷测得结果与电感耦合等离子体原子发射光谱法(ICP-AES)基本一致,锡和锑与原子荧光光谱法(AFS)基本一致,铁、铜、镉和铅与采用锌基体分离—ICP-MS基本一致。     

Identification of urinary oligosaccharides by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

A new method of urinary oligosaccharides identification by matrix-assisted laser desorption time-of-flight mass spectrometry is presented. The method involves three steps: coupling of the urinary oligosaccharides with 8-aminonaphthalene-1,3,6-trisulfonic acid; fast purification over a porous graphite carbon extraction column; and mass spectrometric analysis. Identification of urinary oligosaccharides is based on the patterns and values of the pseudomolecular ions observed. We report here the patterns in urines from patients with Pompe disease, alpha and beta mannosidoses, galacto-sialidosis, and GM1 gangliosidosis. The protocols described here allowed facile and sensitive identification of the pathognomonic oligosacchariduria present in lysosomal diseases and can be extended to any pathological oligosacchariduria.