电感耦合等离子体质谱法测定地质样品中银研究进展

应用电感耦合等离子体质谱（ICP-MS）测定地质样品中银时,锆、铌等元素干扰银的测定,造成准确度低、测定偏差大。采用银的富集、王水偏提取和化学分离法等方法可对干扰元素预分离,从而准确测定样品中银;而应用干扰校正方程及碰撞/反应池（CRC-ICP-MS）、膜去溶（DSN-ICP-MS）、激光剥蚀（LA-ICP-MS）和高分辨质谱（HR-ICP-MS）等新技术,能够更加方便、准确测定地质样品中银。     

EDTA滴定法连续测定锆-铁-钇含量

探讨了准确测定废旧锆钇陶瓷回收时产生的酸性溶液中锆、铁、钇的含量时,乙酰丙酮、三乙醇胺和柠檬酸等铁离子掩蔽剂,以及偶氮砷Ⅲ、甲基百里酚蓝和二甲酚橙等指示剂对测定结果的影响,确定仅以二甲酚橙为指示剂,盐酸羟胺为还原剂,用EDTA滴定法连续测定了溶液中的锆、铁、钇含量,测定结果的RSD<2%。     

紫外导数光谱法直接测定含油污水中的苯胺类

在ｐＨ为２．５的盐酸介质中，用紫外四阶导数光谱法直接测定含油污水中的苯胺类，不需要预蒸馏、萃取、显色等繁杂过程。苯酚、石油类、悬浮物、硫化物等均不干扰测定。含油污水中苯胺类测定的结果与禁乙二胺偶氮比色法的测定结果基本吻合。本方法检出限低、回收率好、操作简便。适用于油矿区污水中苯胺类的监测。     

X射线荧光光谱法测定聚乙烯树脂中微量铬

X射线荧光光谱法应用于各种材料中元素测定,其含量分析范围为1×10-3%～100%,具有测定元素范围广、测定精度高、分析速度快、非破坏性分析等特点.     

气相色谱法测定痕量氟方法的研究

气相色谱法测定有机硅化合物中的痕量氟是60年代末发展起来的,1967年Bock和Semmer^[1]用三乙基氯硅烷等有机硅化合物萃取,用半饱和NaHCO₃反萃测定氟,并建议可用GC法直接测定三乙基氟硅烷,1968年Fressen等^[2]用气相色谱法测定氟,近20年来,气相色谱法测定氟在环境监测、卫生防疫等方面得到应用^[3,4]。     

火焰原子吸收光谱法测定温泉矿泉水中微量元素

用火焰原子吸收光谱仪对乌鲁木齐市水磨沟区温泉矿泉水中的铜、钾、锌、钙、镁等微量元素进行了分析测定,并探讨了酸度、干扰离子对测定的影响.同时用吸光光度法测定了矿泉水中铁,用容量分析法测定了矿泉水中硫化氢,取得较好的结果.     

原子荧光光谱法测定铅精矿中的砷量

研究了原子荧光光谱法测定铅精矿中砷的分析方法;考察了仪器条件、酸度、KBH4浓度及共存元素等对砷测定的影响。该方法适用于铅精矿中砷的测定。     

Easylyte Na/K/Cl电解质分析仪常见故障的排除

叙述Easylyte Na／K／Cl电解质分析仪的常见液路、定标、机械故障，无法测定、测定值不准等故障及故障排除方法。     

电感耦合等离子体质谱法测定水中痕量元素

应用电感耦合等离子体质谱法测定了水样(地下水、地表水、饮用水等)中51项痕量元素,对分析条件包括测定同位素的选择、仪器的工作参数、方法的精密度及检出限的测试等进行了研究。应用此方法测定了混合标准中51项元素,所得测定值与标准值相符,相对偏差(除钨外)均小于±10%,回收率在90%~110%之间。,     

亚硝基R盐分光光度法测定合金钢中钴

本文改进了亚硝基R盐分光光度法测定合金钢中钴的分析方法,并详细探讨了该方法中吸收波长、缓冲溶液、氧化剂、消解酸种类、加热时间、共存离子等测定条件对结果准确度和精密度的影响.结合示差光度法,在不需分离铁、铜、镍、铬等干扰元素的条件下,可适用于测定合金钢中高含量钴,相对误差在3%以下,相对标准偏差小于1%.测定高含量钴标准...     

Development of quadrupole mass spectrometers using rapid prototyping technology

In this report, we present a prototype design of a quadrupole mass filter (QMF) with hyperbolic electrodes, fabricated at the University of Liverpool using digital light processing (DLP), a low-cost and lightweight 3D rapid prototyping (RP) technique. Experimental mass spectra are shown for H₂⁺, D₂⁺, and He⁺ ions to provide proof of principle that the DLP mass filter is working as a mass analyzer in the low-mass range (1 to 10 amu). The performance of the DLP QMF has also been investigated for individual spectral peaks. Numerical simulations of the instrument were performed by coupling CPO and Liverpool QMS-2 programs to model both the ion source and mass filter, respectively, and the instrument is shown to perform as predicted by theory. DLP thus allows miniaturization of mass spectrometers at low cost, using hyperbolic (or other) geometries of mass analyzer electrodes that provide optimal ion manipulation and resolution for a given application. The potential of using RP fabrication techniques for developing miniature and microscale mass analyzers is also discussed.     

Characterization of five [C4H7O]+ Ion structures. Fragmentation of the 2-pentanone molecular ion

The [C₄H₇0]⁺ ions [CH₂?CH? C(?OH)CH₃]⁺ (1), [CH₃CH?CH? C(?OH)H]⁺ (2), [CH₂?C(CH₃)C(?OH)H]⁺ (3), [Ch₃CH₂CH₂C?O]⁺ (4) and [(CH₃)₂CHC?O]⁺ (5) have been characterized by their collision-induced dissociation (CID) mass spectra and charge stripping mass spectra. The ions 1–3 were prepared by gas phase protonation of the relevant carbonyl compounds while 4 and 5 were prepared by dissociative electron impact ionization of the appropriate carbonyl compounds. Only 2 and 3 give similar spectra and are difficult to distinguish from each other; the remaining ions can be readily characterized by either their CID mass spectra or their charge stripping mass spectra. The 2-pentanone molecular ion fragments by loss of the C(1) methyl and the C(5) methyl in the ratio 60:40 for metastable ions; at higher internal energies loss of the C(1) methyl becomes more favoured. Metastable ion characteristics, CID mass spectra and charge stripping mass spectra all show that loss of the C(1) methyl leads to formation of the acyl ion 4, while loss of the C(5) methyl leads to formation of protonated vinyl methyl ketone (1). These results are in agreement with the previously proposed potential energy diagram for the [C₅H₁₀O]⁺˙ system.     

Investigation of lacidipine,a new 1,4-dihydropyridine antihypertensive agent and three chemically related compounds by means of chemical ionization,mass spectrometry and collision-induced dissociation

Chemical ionization of two 1,4-dihydropyridines, lacidipine and its Z-isomer, and their corresponding pyridines in three different reagent gases and the collision-induced dissociation (CID) of their respective mass-selected protonated molecular ions in the collision energy range 10–200 eV were performed on a multiple quadrupole instrument. The weakness of the Breasted acid NH₄⁺ as a protonating agent is clearly manifested in one of the ammonia positive-ion chemical ionization (CI⁺) mass spectra which displays the addition ion, [M + NH₄]⁺, as the favoured reaction channel. The stereochemistry of the precursor molecules, the exothermicity of the protonation process and the threshold of certain dissociation channels as a function of the collision energy are among the arguments invoked to explain some of the observed differences between the CI⁺ mass spectra and the CID data of the different isomers investigated. In an attempt to present a more comprehensive study, some high-performance liquid chromatographic retention times and resolutions are also given.     

Characterization of N‐methylated amino acids by GC‐MS after ethyl chloroformate derivatization

Methylation is an essential metabolic process in the biological systems, and it is significant for several biological reactions in living organisms. Methylated compounds are known to be involved in most of the bodily functions, and some of them serve as biomarkers. Theoretically, all α‐amino acids can be methylated, and it is possible to encounter them in most animal/plant samples. But the analytical data, especially the mass spectral data, are available only for a few of the methylated amino acids. Thus, it is essential to generate mass spectral data and to develop mass spectrometry methods for the identification of all possible methylated amino acids for future metabolomic studies. In this study, all N‐methyl and N,N‐dimethyl amino acids were synthesized by the methylation of α‐amino acids and characterized by a GC‐MS method. The methylated amino acids were derivatized with ethyl chloroformate and analyzed by GC‐MS under EI and methane/CI conditions. The EI mass spectra of ethyl chloroformate derivatives of N‐methyl ( 1–18 ) and N,N‐dimethyl amino acids ( 19–35 ) showed abundant [M‐COOC₂H₅]⁺ ions. The fragment ions due to loss of C₂H₄, CO₂, (CO₂ + C₂H₄) from [M‐COOC₂H₅]⁺ were of structure indicative for 1–18 . The EI spectra of 19–35 showed less number of fragment ions when compared with those of 1–18 . The side chain group (R) caused specific fragment ions characteristic to its structure. The methane/CI spectra of the studied compounds showed [M + H]⁺ ions to substantiate their molecular weights. The detected EI fragment ions were characteristic of the structure that made easy identification of the studied compounds, including isomeric/isobaric compounds. Fragmentation patterns of the studied compounds ( 1–35 ) were confirmed by high‐resolution mass spectra data and further substantiated by the data obtained from ¹³C₂‐labeled glycines and N‐ethoxycarbonyl methoxy esters. The method was applied to human plasma samples for the identification of amino acids and methylated amino acids. Copyright © 2016 John Wiley & Sons, Ltd.     

The synthesis of novel crown ethers,part X, 4‐propyl‐and 3‐ethyl‐4‐methylchromenone‐crown ethers

Starting from ethyl propionylacetate, and ethyl 2‐ethylacetoacetate we prepared 4‐propyl‐7,8‐, 4‐propyl‐6,7‐, 3‐ethyl‐4‐methyl‐7,8‐ and 3‐ethyl‐4‐methyl‐6,7‐dihydroxy‐2H‐chromenones which were allowed to react with the bis‐dihalides or ditosylates of glycols in DMF/Na₂CO₃ to afford the 6,7‐ and 7,8‐chromenone derivatives of 12‐crown‐4, 15‐crown‐4 and 18‐crown‐6. The products were identified using ir, ¹³C and ¹H nmr, ms and high resolution mass spectroscopy. The cation selectivities of chromenone crown ethers with Li⁺, Na⁺ and K⁺ cations were estimated from the steady state emission fluorescence spectra of free and cation complexed chromenone macrocyclic ethers in acetonitrile.     

APCI as an innovative ionization mode compared with EI and CI for the analysis of a large range of organophosphate esters using GC‐MS/MS

Organophosphate esters (OPEs) are chemical compounds incorporated into materials as flame‐proof and/or plasticizing agents. In this work, 13 non‐halogenated and 5 halogenated OPEs were studied. Their mass spectra were interpreted and compared in terms of fragmentation patterns and dominant ions via various ionization techniques [electron ionization (EI) and chemical ionization (CI) under vacuum and corona discharge atmospheric pressure chemical ionization (APCI)] on gas chromatography coupled to mass spectrometry (GC‐MS). The novelty of this paper relies on the investigation of APCI technique for the analysis of OPEs via favored protonation mechanism, where the mass spectra were mostly dominated by the quasi‐molecular ion [M + H]⁺. The EI mass spectra were dominated by ions such as [H₄PO₄]⁺, [M–R]⁺, [M–Cl]⁺, and [M–Br]⁺, and for some non‐halogenated aryl OPEs, [M]^+● was also observed. The CI mass spectra in positive mode were dominated by [M + H]⁺ and sometimes by [M–R]⁺, while in negative mode, [M–R]⁻ and more particularly [X]^‐ and [X₂]^‐● were mainly observed for the halogenated OPEs. Both EI and APCI techniques showed promising results for further development of instrumental method operating in selective reaction monitoring mode. Instrumental detection limits by using APCI mode were 2.5 to 25 times lower than using EI mode for the non‐brominated OPEs, while they were determined at 50‐100 times lower by the APCI mode than by the EI mode, for the two brominated OPEs. The method was applied to fish samples, and monitored transitions by using APCI mode showed higher specificity but lower stability compared with EI mode. The sensitivity in terms of signal‐to‐noise ratio varying from one compound to another. Copyright © 2016 John Wiley & Sons, Ltd.     

Study of synthetic aliphatic copolyamides by time-of-flight matrix assisted laser desorption/ionization mass spectrometry

Synthetic copolyamides based on aliphatic diamines (1,3-propanediamine and 1,4-butanediamine) and dichlorides of aliphatic carboxylic acids (adipic and sebacic acid dichlorides) were investigated using time-of-flight matrix assisted laser desorption/ionization mass spectrometry. Their mass spectra showed peaks for cationized (Na⁺ and K⁺) and protonated (less intense peaks) oligomers with NH₂-NH₂, NH₂-COOH, or COOH-COOH end groups. No cyclic oligomers were detected in the samples. The compositions of oligomers were determined, and the relative reactivities of homologous comonomers in polycondensation were estimated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1320–1324, July, 2007.     

Fast atom bombardment (FAB) mass spectrometry of piperidine N-oxide derivatives and free radical quenching under FAB conditions

Mechanisms are proposed for the formation of M⁺, [M + 2H]⁺ and [M + 3H]⁺ ions in the fast atom bombardment (FAB) mass spectra of 4-(2,2,6,6-tetramethyl-1-oxyl)-piperidol and its carboxylates. Free radical quenching induced by the fast atom beam has been observed. The effects of temperature on the radical quenching and of acid on the FAB mass spectra are discussed. The experiment showed that the volatile liquid samples with vapour pressures higher than that for glycerol produced M⁺ even-electron molecular ions, and the FAB mass spectra were similar to the corresponding electron ionization mass spectra. For the solid samples, it was found that the free radicals were quenched during the FAB process so that the mononitroxide and dinitroxide compounds produced [M + 2H]⁺ and [M + 3H]⁺ ions, respectively. Further experiments showed that the intensities and stabilities of [M + 2H]⁺ and [M + 3H]⁺ ions could be improved by addition of acids.     

Enhanced positive secondary ion emission from substituted polynuclear aromatic hydrocarbon/sulfuric acid solutions

Secondary ion mass spectra of singly substituted aromatic hydrocarbon/H₂SO₄ solutions showed intense aromatic molecular ion and protonated aromatic molecule peaks characteristic of dissolved aromatic compounds from a number of aromatic compound classes, including acids, aldehydes, ketones, nitriles and nitrogen heterocycles. The presence of simultaneously abundant peaks for molecular ions and protonated molecules in secondary ion mass spectra of each aromatic compound/sulfuric acid solution is consistent with known or expected gas-phase proton transfer chemistry. The ratio of intensities, M⁺˙:[M + H]⁺, appears to be determined by sulfuric acid solution chemistry of the compound. Spectra obtained from 1–2 μl samples were relatively free from chemical noise and persisted for up to 20 min. Detection limits for some substituted aromatic compounds are estimated to be 10^?12.     

Characterization of [peptide+(Ag)n]+ complexes using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Silver ion complexes of peptides [M + (Ag)_n]⁺, M = angiotensin I or substance P where n = 1–8 and 17–23 for angiotensin I and n = 1–5 for substance P, are identified and characterized using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). The Ag⁺ coordination number exceeds the number of available amino acid residues in angiotensin I whereas the number of observed complexes in substance P is less than the number of amino acid residues in it. The larger coordination number of angiotensin I with Ag⁺ indicates the simultaneous binding of several Ag⁺ ions to the amino acid residue present in it. The lower number of observed complexes in substance P suggests the binding of two or more residues to one Ag⁺ ion. The presence of trifluoroacetic acid in the peptide samples reduces the Ag⁺ coordination ability in both the peptides which indicates that the basic residues in it are already protonated and do not participate in the Ag⁺‐binding process. The Ag⁺ ion also forms a complex with the α‐cyano‐4‐hydroxycinnamic acid (CHCA) matrix and is observed in the MALDI mass spectra and the formation of [CHCA + Ag]⁺, [CHCA + AgNO₃]⁺ and [(CHCA)₂ + Ag]⁺ ions is due to the high binding affinity of Ag⁺ to the CN group of CHCA. Copyright © 2010 John Wiley & Sons, Ltd.