共查询到20条相似文献,搜索用时 187 毫秒
1.
有机化合物中氟的微量测定长期以来沿用容量法,其缺点是不符合化学计量和滴定终点不明显。氟离子电极用于有机化合物中氟的测定方法近年来已有一些文献介绍,一般首先将有机氟化物经燃烧分解转化成氟离子,然后应用氟离子电极以电位滴定法或直接电位法进行测定。但这两种方法,或手续繁复,或因磷、砷元素的干扰等因素影响了分析结果的准确度。我们针对上述缺点,建立一种用石英燃烧瓶分解样品和以氟离子电极标准加入法相结合的测定方法。含氟有机样品经燃烧分解后不必转移,即可在分解样品的石英瓶中测得标准氟离子溶液加入前后的 相似文献
2.
以氟化镧单晶为敏感膜的氟离子选择电极,由于操作简便、干扰离子少,可在许多方面用于氟的定量分析。此法在有机氟元素微量分析中也已被应用。我们采用玻璃燃烧瓶分解样品,以柠檬酸钠为吸收液,用氟离子选择电极测定有机物中氟的含量,用格氏作图法处理数据,得到了较好的结果。实验部分(一)仪器与试剂 1.DD-2型电极电位仪(江苏泰县无线电厂)。 2.氟离子选择电极:CSB-F-1型氟化镧 相似文献
3.
元素分析仪法是测定有机元素含量的现代分析技术,一次进样可以同时测定化合物中的C、H、N等元素的含量,在元素含量分析中发挥了重要作用,但该方法对卤族元素无法测定.氧瓶燃烧分解样品后用电位滴定法或称(容)量法测定有机卤素的含量,是有机卤素分析的经典方法.国家标准测定聚氯乙烯样品中的氯含量采用氧瓶燃烧分解电位滴定法[1].电位滴定法一次只能测定样品中一种卤离子,若多种离子同时存在会产生干扰,影响测定结果,且需要配制多种试剂,费时费力.有机样品或聚合物经氧瓶燃烧法分解后采用离子色谱法一次进样可以同时测定多种元素的含量而互不干扰[2],分析速度和灵敏度都优于传统方法.许多有机化合物或聚合物都含有卤素,离子色谱对卤素离子测定的灵敏度很高,氧瓶燃烧离子色谱法弥补了元素分析仪法的不足,是有机化合物或聚合物卤素含量分析较理想的方法.本实验以间氯苯甲酸元素分析标准样品为对照品,测定了氯化聚乙烯中的氯含量,取得满意结果. 相似文献
4.
提出氧瓶分解-碘离子选择电极法用于有机碘化物中碘的微量分析.方法简便、快速,终点突跃,绝对误差小,氮、氟、硫、磷、砷等元素不干扰测定. 相似文献
5.
6.
王昌益 《高等学校化学学报》1981,2(3):327
提出氧瓶分解-汞离子选择性电极法于有机化合物中汞的微量分析。所拟定方法简便、快速,终点突跃,绝对误差±0.3%,化合物中存在氮、氟、硫、磷、硼、硅、钾、钠等元素不干扰测定。 相似文献
7.
8.
介绍了用氧瓶分解-离子色谱测定胱氨酸标准物质中硫元素含量的方法。以美国进口胱氨酸标准物质为样品,用氧瓶燃烧分解,以碱性吸收液吸收,使硫元素转化为硫酸根阴离子,然后进行离子色谱分析。分析数据与标准物质标称值进行了比较,结果令人满意。 相似文献
9.
10.
建立了自动快速燃烧(AQF)-离子色谱联用测定铜精矿中氟的方法。将 AQF 的自动化特性和离子色谱的灵敏度高、准确性好的特点结合起来,能够实现操作过程的连续自动化。结果表明,线性范围内(1.0?50.0 μg )校准曲线相关系数 r >0. 999,氟的检出限为0.0004%。按照实验方法测定铜精矿样品中氟,结果的相对标准偏差( RSD ,n =6)为2.14 % ?4.24 %。将实验方法用于铜精矿标准样品氟含量测定,测定值与认定值吻合较好;方法对照试验表明,实验方法对氟含量的测定值与国家标准 GB/T 3884. 12—2010的测定值基本一致。 相似文献
11.
Frost RL Weier M Martens WN 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(3):685-689
Raman microscopy has been used to study the molecular structure of a synthetic goudeyite (YCu(6)(AsO(4))(3)(OH)(6) x 3H(2)O). These types of minerals have a porous framework similar to that of zeolites with a structure based upon (A(3+))(1-x)(A(2+))(x)Cu(6)(OH)(6)(AsO(4))(3-x)(AsO(3)OH)(x). Two sets of AsO stretching vibrations were found and assigned to the vibrational modes of AsO(4) and HAsO(4) units. Two Raman bands are observed in the region 885-915 and 867-870 cm(-1) region and are assigned to the AsO stretching vibrations of (HAsO(4))(2-) and (H(2)AsO(4))(-) units. The position of the bands indicates a C(2v) symmetry of the (H(2)AsO(4))(-) anion. Two bands are found at around 800 and 835 cm(-1) and are assigned to the stretching vibrations of uncomplexed (AsO(4))(3-) units. Bands are observed at around 435, 403 and 395 cm(-1) and are assigned to the nu(2) bending modes of the HAsO(4) (434 and 400 cm(-1)) and the AsO(4) groups (324 cm(-1)). 相似文献
12.
Molten salt reactions of NH4H2AsO4, H3BO3, and MX (M = Li, Na, K, Rb Cs, NH4 and X = F, Cl, Br) yield numerous new alkali metal and alkali metal salt templated three-dimensional boroarsenate and fluoroboroarsenate frameworks. The structures of these materials are formed from BO4 (BO3F) and As(O,OH)4 tetrahedra defining channels and interlayer regions containing either simple alkali metal cations or both cations and halide anions. These boroarsenate-based frameworks are unusual in comparison with other oxotetrahedral-based materials in that terminal OH, on As, may be present, decorating the inner surfaces of the channels, as in the 12-membered rings of K2[B(AsO3O)2H]. This unit also permits coordination to nonframework anions as well as cations, so that (Cs2[BAsO3OH]8[AsO4]2[CsCl4]Cl)2 (and its Br analogue) contains layers of [CsCl4]3- and Cl- ions separated and coordinated by the protonated boroarsenate framework. 相似文献
13.
A rapid and simple general complexometric method was presented for the determination of lead, cadmium and thallium or mercury or arsenic(V) in laboratory synthesized mixtures similar to those of some ores, minerals and alloys of such metals. The precision and accuracy attainable in successive titrations of Pb(2+), Cd(2+) and Tl(3+) or Hg(2+) or AsO(3-)(4) (As(5+)) with 0.05 and/or 0.01 mol 1(-1) solutions of disodium ethylenediaminetetraacetate (Na(2)EDTA) and standard Pb(NO(3))(2) of the same concentration using Bromo-Cresol Orange (BCO) as a new metallochromic indicator with visual endpoint indication were studied. For the analysis of a three component mixtures of the aforementioned ions, Tl(3+) was at first directly titrated with Na(2)EDTA at pH 0.5-1 (HNO(3)) using BCO as indicator. At the thallium endpoint an excess of Na(2)EDTA was added and the pH was adjusted at pH approximately 4.8 using hexamine-HNO(3) buffer (solution A). The excess EDTA was back-titrated with standard solution of Pb(NO(3))(2). 1,10-Phenanthroline (1,10-phen) was added to release the EDTA combined with Cd(2+), while thiosemicarbazide (TSC) was used to liberate the EDTA from the mercury-EDTA chelate. To determine AsO(3-)(4) ion in such type of mixtures the pH of (solution A) was raised to a value of 10 using ammonia buffer. Excess standard Mg(2+) solution was added and the formed precipitate of MgNH(4)AsO(4) was separated, dissolved and its magnesium content equivalent to AsO(3-)(4) was determined complexometrically using Eriochrome Black-T (EBT) indicator. The interference caused by different anions, cations and organic acids was investigated. A comparison of the indicators BCO and Xylenol Orange (XO) for successive titration of the studied metal ions was carried out. The proposed successive titration method was applied successfully to some real samples of ores, minerals and alloys of the studied metal ions and the results were satisfactory and agreed with those obtained by AAS. 相似文献
14.
Frost RL Xi Y Tan K Millar GJ Palmer SJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2012,85(1):173-178
Some minerals are colloidal and show no X-ray diffraction patterns. Vibrational spectroscopy offers one of the few methods for the determination of the structure of these minerals. Among this group of minerals is pitticite, simply described as (Fe, AsO(4), SO(4), H(2)O). In this work, the analogue of the mineral pitticite has been synthesised. The objective of this research is to determine the molecular structure of the mineral pitticite using vibrational spectroscopy. Raman and infrared bands are attributed to the AsO(4)(3-), SO(4)(2-) and water stretching and bending vibrations. The Raman spectrum of the pitticite analogue shows intense peaks at 845 and 837cm(-1) assigned to the AsO(4)(3-) stretching vibrations. Raman bands at 1096 and 1182cm(-1) are attributed to the SO(4)(2-) antisymmetric stretching bands. Raman spectroscopy offers a useful method for the analysis of such colloidal minerals. 相似文献
15.
16.
Separation of arsenic species by capillary electrophoresis with sample-stacking techniques 总被引:1,自引:0,他引:1
A simple capillary zone electrophoresis procedure was developed for the separation of arsenic species (AsO(2)(2-), AsO(4)(2-), and dimethylarsinic acid, DMA). Both counter-electroosmotic and co-electroosmotic (EOF) modes were investigated for the separation of arsenic species with direct UV detection at 185 nm using 20 mmol L(-1) sodium phosphate as the electrolyte. The separation selectivity mainly depends on the separation modes and electrolyte pH. Inorganic anions (Cl(-), NO(2)(-), NO(3)(-) and SO(4)(2-)) presented in real samples did not interfere with arsenic speciation in either separation mode. To improve the detection limits, sample-stacking techniques, including large-volume sample stacking (LVSS) and field-amplified sample injection (FASI), were investigated for the preconcentration of As species in co-CZE mode. Less than 1 micromol L(-1) of detection limits for As species were achieved using FASI. The proposed method was demonstrated for the separation and detection of As species in water. 相似文献
17.
Frost RL Weier M Martens W 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(1):60-65
Raman spectroscopy has been used to identify whether or not a selection of minerals labelled as mixites (formula BiCu6(AsO4)3(OH)6.3H2O) are correctly marked. Of the four samples, two samples are shown to be potentially mixites because of the presence of the characteristic Raman spectra of (AsO4)3- units and (HAsO4)- units, characterised by bands at around 803 and 833 cm(-1). Two of the minerals are shown to be predominantly carbonates. Bands are observed at 3473.9 and 3470.3 cm(-1) for the two mixite samples. Bands observed in the region 880-910 cm(-1) and in the 867-870 cm(-1) region are assigned to the AsO stretching vibrations of (HAsO4)2- and (H2AsO4)- units. Whilst bands at around 803 and 833 cm(-1) are assigned to the stretching vibrations of uncomplexed (AsO4)3- units. Intense bands observed at 473.7 and 475.4 cm(-1) are assigned to the nu4 bending mode of AsO4 units. Bands observed at around 386.5, 395.3 and 423.1 cm(-1) are assigned to the nu2 bending modes of the HAsO4 (434 and 400 cm(-1)) and the AsO4 groups (324 cm(-1)). Raman spectroscopy lends itself to the identification of minerals on host matrices and is especially useful for the identification of mixites. 相似文献
18.
Bazán B Mesa JL Pizarro JL Aguayo AT Arriortua MI Rojo T 《Chemical communications (Cambridge, England)》2003,(5):622-623
The new orthorhombic Fe(AsO4) phase has been synthesized by thermal treatment at 525 degrees C of a new (NH4)[Fe(AsO4)F] compound, with a [Fe(AsO4)F]- skeleton showing channels where the ammonium cations are located. The crystal structure of Fe(AsO4) has been solved from single-crystal data. The structure is formed by layers of edge-sharing dimeric octahedra, and interconnected by chains of alternating FeO6 octahedra and AsO4 tetrahedra. 相似文献
19.
The molecules AsOCl and SbOCl are formed by reactions of silver with mixtures of AsCl3 and O2 or SbCl3 and O2 respectively at about 1300 K. After condensation in an argon matrix at 15 K the two stretching vibrations of AsOCl can be observed in the IR spectrum: 984.4 cm−1 [ν(AsO)] and 378.7 cm−1 [ν(AsCl)]. This assignment is confirmed by the measured 16O/18O and 35Cl/37Cl isotopic shifts. The calculated AsO force constant shows that there is a real AsO double bond in this molecule.
We failed in the characterisation of SbOCl by the same method, because this molecule is only stable at 1350 K in the presence of gaseous Sb4O6 and therefore the absorptions of SbOCl are superimposed by the very strong bands of Sb4O6. 相似文献
20.
Frost RL Palmer SJ Xi Y 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,83(1):444-448
Some minerals are colloidal and are poorly diffracting. Vibrational spectroscopy offers one of the few methods for the assessment of the structure of these types of minerals. Among this group of minerals is zykaite with formula Fe(4)(AsO(4))(SO(4))(OH)·15H(2)O. The objective of this research is to determine the molecular structure of the mineral zykaite using vibrational spectroscopy. Raman and infrared bands are attributed to the AsO(4)(3-), SO(4)(2-) and water stretching vibrations. The sharp band at 3515 cm(-1) is assigned to the stretching vibration of the OH units. This mineral offers a mechanism for the formation of more crystalline minerals such as scorodite and bukovskyite. Arsenate ions can be removed from aqueous systems through the addition of ferric compounds such as ferric chloride. This results in the formation of minerals such as zykaite and pitticite (Fe(3+), AsO(4), SO(4), H(2)O). 相似文献