铌—钛—钽及铌—钛合金中微量钨、钼的连续催化极谱测定

铌—钛—钽及铌—钛合金中微量钨钼的连续测定用其他方法有一定困难。有色金属研究总院金静如工程师用连续催化极谱测定,方法简便、快速,结果良好。考虑了测定中各种因素的影响,她拟定的最佳示波极谱测定的底液条件。该条件为0.7N硫酸—0.25％苦杏仁酸—3％氯酸钾—0.08％辛可宁—0.0015％8-羟基喹啉。在此体系中0—10微克钨,0—6微克钼(50毫升体积)浓度与波高成比例关系。200倍钼不干扰钨的测定,20倍钨不干扰钼的测定。400     

钼—羟胺—5-Br-PADAP三元络合物分光光度法测定钨矿中微量钼

前文报导了用钼—羟胺—(5—Br—PADAP)三元络合物分光光度法测定微量钼,并对八种不同的标准钢样和两个管理矿样中的微量钼进行了测定,得到满意的结果。证明本法的应用范围较广泛,灵敏度亦高,准确性也好。我们应用于几个钨矿中微量钼的直接测定,也得到较满意的结果。 试剂:混合掩蔽剂,取74.4克EDTA、10克环已烷二胺四乙酸、121.5克柠檬酸铵,加水和几颗氢氧化钠进行溶解并用水稀至1升;其它试剂的配制同前文。     

8-羟基喹啉一钼(Ⅵ)吸附波测定钢铁中微量钼

钼的催化极谱测定国内外已有不少报导,但在硝酸—硝酸钠底液中,8—羟基喹啉—钼配合物在悬汞电极上吸附催化还原,测定钢铁中微量钼还少见。本文研究了在0.7M NaNO_3—0.01M HNO_3—3×10~(-4)M8—羟基喹啉体系中(pH～1.9),8—羟基喹啉—钼配合物的吸附催化波,其导数峰电位     

氧屏蔽空气-乙炔火焰原子吸收法测定钢中的钼

文献首先报导原子吸收分光光度法测定钼,并指出必须使用富燃气空气—乙炔火焰。但当应用于微量钼分析时,由于灵敏度低而难以实现。同时各共存元素对测定钼的干扰也是相当复杂的。用笑气—乙炔火焰测定钼效果更好,如果选择最佳条件时,可成功地测定钢中0.001～6％的钼,且比空气—乙炔火焰测定钼时干扰少。但鉴于笑气昂贵,气源供应不便,我们对氧屏蔽空气—乙炔火焰测定钢中钼进行了研究。由于氧屏蔽空气—乙炔火焰有较高的温度及较强的还原性,所以测定钼的灵敏度虽     

矿石中钼的快速示波极谱测定

我们经常分析的选矿试样要求测定含量0.00X～X%的钼.现行硫氰酸盐比色法需预先分离干扰元素,测定手续较为麻烦.国内有些单位利用钼的极谱催化波测定矿石中微量钼,但不适宜测定较高浓度的钼.J.B.Headridge等研究了在0.5M柠檬酸—0.025M硫酸—0.05M硝酸钍(pH3.5)介质中钼的极谱波[2],指出钼在此体系中有Mo(Ⅵ→Ⅴ)和Mo(Ⅴ→Ⅲ)的两个波,并利用钼的第一个波测定铌基合金中约4%的钼.关于硫酸—柠檬酸底液在钼的矿石分析中的应用,尚未见到资料介绍.本文研究了钼在硫酸—柠檬酸体系中的第     

钼(Ⅵ)-4,5-二溴苯基荧光酮——不同表面活性剂显色反应的研究及其分析应用

研究了4,5-二溴苯基荧光酮(DBPF)在不同表面活性剂存在下和钼的反应特性,选择了最佳显色体系Mo(VI)-DBPF-OP;同时研究了显色反应条件及干扰情况,提出了直接光度测定钢铁及其他合金中微量钼的方法。该法适于0.x～0.005％含量范围钼的测定。     

四丁基溴化铵—碘化钾—盐酸底液中微量镉的示波极谱测定

极谱测定微量镉,前人已作过许多工作,其中盐酸—碘化钾—四乙基碘化铵极谱测定微量镉的体系,灵敏度比氨性底液的方法提高了很多,选择性也好,但在 2微克以下线性关系不好,且铟等的干扰较大。我们在此基础上作了改进,采用四丁基溴化铵—碘化钾—盐酸体系测定微量镉,灵敏度又有提高,在25毫升体积中,0.2～6微     

邻羟基萘基荧光酮—CTMAB光度法测定微量钼

本文介绍了邻羟基萘基荧光酮—CTMAB光度法测定微量钼。所生成的配合物在波长514nm处的摩尔吸光系数ε=1.17×10~5。在钼浓度0～10.0μg/25ml范围内符合比尔定律。该法有很好的选择性,许多其它金属离子不干扰测定。它已直接用于测定钢和合金中钼,获得了令人满意的结果。     

导数分光光度法测定钢中的磷

本文采用磷钒钼蓝—罗丹明B—明胶—OP体系以一阶导数分光光度法测定了碳素工具钢和低合金钢中的磷。对三种标准钢样测定的结果,最大相对标准偏差为5.8％,回收率在94～107％之间。     

砷钒钼杂多酸—乙基紫—OP—10分光光度法测定微量砷

三苯甲烷类碱性染料——乙基紫已广泛用于萃取光度法。目前,乙基紫已用於测定微量锑、铼、铊、银、金、汞、钽、碘和磷。但萃取光度法操作手续麻烦,而且易引进误差。近年来也有人用砷钼蓝—孔雀绿水相分光光度法测定微量砷(c=7.5×10~4。我们采用胶束增溶法即以乙基紫作显色剂,OP—10作增溶剂,使砷钒钼杂多     

An increase in purity of ammonium perrhenate solutions with respect to molybdenum(IV) with the sorption recovery of rhenium(VII) from Mo-containing solutions

The possibility of the additional purification of ammonia rhenium desorbates with respect to molybdenum in the course of the sorption recovery of rhenium from Mo-containing solutions with the help of Purolite A170 and Purolite A172 weak base anion-exchange resins is considered. The pH-dependence of sorption of Re(VII) and Mo(VI) on these anion-exchange resins is investigated in static conditions with the 1 M (NH₄)₂SO₄ background in the solution. It is shown that the range of pH, in which anion-exchange resins retain the ability to sorb Re(VII), is also spread to a weakly basic region. A substantial decrease in the adsorption of Re(VII) starts already with an increase in pH above 7.5. The capacity of anion-exchange resins with respect to Mo(VI) starts to decrease noticeably with an increase in pH of solutions above 5.0, and molybdenum almost ceases to sorb by both anion-exchange resins upon reaching pH ~ 7.0. In order to decrease the Mo(VI) content in rhenium desorbates with the sorption recovery of Re(VII) from Mo-containing solutions on weak base anion-exchange resins, the following flowsheet is suggested. Initially, the main amount of sorbed Mo(VI) is desorbed by contacting the saturated anion-exchange resin with the ammonium sulfate solution upon mixture stirring and holding constant pH of the solution in limits of 7.0–7.5 due to the addition of dosed amounts of ammonia solution. Then anion-exchange resin is separated from the ammonium sulfate solution containing Mo(VI), washed with water, and Re(VII) is desorbed by ammonium solution in dynamic conditions. The verification of the proposed method for the resins saturated by sorption from the model solution of the composition, g/L, 98 H₂SO₄, 4 Mo(VI), and 0.5 Re(VII) showed the occurrence of desorption of no less than 90% sorbed molybdenum during the treatment of anion-exchange resins with ammonium sulfate solution. Herewith, concentration ratio Re(VII) : Mo(VI) in ammoniacal rhenium desorbates when using A170 anion-exchange resin increases 11-fold and when using A172 anion-exchange resin, it increases 20-fold compared with that attained without the additional washing of Mo(VI). Losses of Re(VII) with the Mo-containing desorbate (reversible) do not exceed 5.2% of the amount of sorbed Re(VII).     

极化电极电位滴定法直接测定镍基电热合金中镍

镍基合金中镍可以用丁二酮肟乙醇溶液直接滴定,以恒电流电位滴定法指示终点。所用的极化电极系统为,极电电流为2uA。滴定在PH11的氨性缓冲溶液中进行,温度保持在40～50℃左右。滴定曲线在等当点有—个尖锐的峰。大量的普通金属离子:Mn~(2+)、Fe~(2+)、Al~(3+)、Fe~(3+)、RE~(3+)、Ti~(4+)、Sn~(4+)、V(V)、Mo(Ⅵ)、W(Ⅵ)、Cr(Ⅵ)及适量的Cr~(3+)、Cu~(2+)、Co~(2+)以及阴离子均不干扰,滴定具有较高的选择性。     

A comparison of the extraction capacity of trioctylamine and its radiolytic products dioctylamine and primary octylamine for the elements U(VI), Mo(VI), Zr(IV) and Sr(II)

The percentage extraction of the elements U(VI), Mo(VI), Zr(IV) and Sr(II) from 1–6 M nitric acid by trioctylamine (TOA) and its radiolytic degradation products dioctylamine (DOA) and primary octylamine (POA) in xylene have been measured. TOA and DOA showed similar extraction capacities for Zr(IV), but DOA was less effective than TOA for U(VI) and Mo(VI), Sr(II) was not extracted by any of these amines. These results suggest that the use of the “Zirconium number” is in itself not sufficient when considering the resistance of TOA to radiation.     

Kinetic isotope effects and electron transfer in the reduction of xanthine oxidoreductase with 4-hydroxypyrimidine. A comparison between oxidase and dehydrogenase forms

Isolated from bovine milk, xanthine oxidase (XO) and xanthine dehydrogenase (XDH) are two interconvertible forms of the same protein, differing in the number of protein cysteines versus cystines. Most differences between XO and XDH are localized to the FAD center, the site at which the oxidizing substrates NAD and molecular oxygen react. A comparative study of the reduction of XO and XDH has been performed to assess differences in reactivity of the molybdopterin site, as well as subsequent electron-transfer events from molybdenum to 2Fe/2S and FAD centers. The compound 4-hydroxypyrimidine (4-OH-P) was chosen as reducing substrate because its higher Km value raised the possibility of binding weak enough to measure kinetically, and its high kcat value could allow detection of intramolecular electron-transfer reactions. As measured by stopped flow spectrophotometry, XO and XDH react with the first equivalent of 4-OH-P via similar mechanisms, differing in the magnitude of rate and dissociation constants. Using [2-2H]4-OH-P as substrate, a D(k/Kd) isotope effect of 1.9 to 2.3 suggests that movement of the hydrogen abstracted from substrate appreciably limits the rate of initial enzyme reduction from Mo(VI) to Mo(IV). Monitoring the visible spectrum of the enzymes, the first observed step is reduction of a single 2Fe/2S center and presumably re-oxidation of Mo(IV) to Mo(V). This suggests a common pathway for electron transfer involving reduction of a 2Fe/2S center prior to reduction of the second 2Fe/2S and FAD centers. Rates of the first electron transfer from molybdenum to the 2Fe/2S center are rapid, 290 s-1 with XO and 180 s-1 with XDH, and are consistent with rates measured by flash photolysis (Walker, M. C., Hazzard, J. T., Tollin, G., and Edmondson, D. E. (1991) Biochemistry 30, 5912-5917) allowing discrete observation of the electron-transfer reactions that occur during turnover. This step also exhibits a modest primary kinetic isotope effect of 1.5 to 1.6 when [2-2H]4-OH-P is used, possibly due to deprotonation of the molybdenum center prior to electron transfer. A second one-electron transfer, presumably oxidizing Mo(V) to Mo(VI), follows in a step coincident with product dissociation, consistent with a role for product release in controlling electron transfer events. The kinetics of this complex system are described and interpreted quantitatively in models that are consistent with all the data.     

Determination of vitamin C in effervescent tablets containing other vitamins together with trace elements

A simple, rapid method is reported for the determination of vitamin C in effervescent tablets containing other vitamins and several trace elements such as Mg(II), Zn(II), Fe(II), Mn(II), Cu(II) and Mo(VI). The procedure was developed on the basis of the bromate ion-iodide ion-ascorbic acid clock reaction (Landolt reaction). Interference effects of air oxygen and metal ions and the role of pH are discussed in detail.     

流动注射-化学发光法测定痕量锇(Ⅳ)的研究及应用

基于丙酮在吐温４０一氢氧化钾一过氧化氢一O_ｓ（Ⅳ）体系中增强Ｏ_ｓ（Ⅳ）的化学发光,采用流动注射进样技术,建立了测定痕量锇（Ⅳ）的新的化学发光分析法．方法的线性范围为１．０Ｘ１~－８～１．０Ｘ１０~－６Ｏ（Ⅳ）／ｍＬ检出限为２．０Ｘ１０~－９ｇ／ｍ,对１０Ｘ１０~－７ｇ／ｍＬＯｓ（Ⅳ）标准溶液测定１１次的相对标准偏差为３．０％．拟定方法用于贵金属精矿中痕量锇的测定,结果满意。本文还进行了增敏机理的探讨．     

A characterization of permolybdate and its effect on cellular tyrosine phosphorylation, gap junctional intercellular communication and phosphorylation status of the gap junction protein, connexin43

Biological and analytical characterizations of permolybdate (a mixture of H2O2 and molybdate) were done. Molybdate (10 mM) and molybdenum(V) chloride (3 mM) did not affect gap junctional intercellular communication (GJIC), phosphorylation status of connexin43 (Cx43) or cellular tyrosine phosphorylation in early passage hamster embryonic cells (mainly fibroblast-like). High concentrations of H2O2 (3-10 mM) affected some of the parameters. Acidified permolybdate was clearly more stable than the unadjusted permolybdate. The maximum biological potency of acidified permolybdate was found at a molar ratio of 2:1 (H2O2:molybdate). The mixtures of molybdenum(V) chloride and H2O2 gave a maximum effect at 4:1 molar ratio (H2O2:molybdenum(V)). This can be explained by decomposition of H2O2 and by the generation of less biologically active compounds. Spectrophotometric analyses of the mixtures corroborated the biological results. The Mo(V) electron spin resonance spectrum disappeared upon addition of H2O2 to Mo(V) solutions, and no spectrum appeared when H2O2 was mixed with Mo(VI). Thus, permolybdate is probably diperoxomolybdate, a Mo(VI) compound. Regardless of the parent metal salt, the H2O2/metal salt mixtures showed concentration-dependent biphasic responses with an initial decrease in GJIC followed by an increase. A dissociation between alteration in Cx43 phosphorylation status and GJIC was obtained under certain conditions. The biological activities of permolybdate were only partially mimicked by phenylarsine oxide, an alternative protein tyrosine phosphatase inhibitor.     

人工神经网络解析分光光度法同时测定钨和钼

用单纯形法优化了钨、钼－二溴羟基苯基荧光酮－ＣＴＭＡＢ显色体系的实验条件。应用三层ＡＮＮ－ＢＰ网络解析钨和钼的吸收光谱,分光光度法同时测定了钨和钼并与偏最小二乘法、因子分析、Ｐ－矩阵法、卡尔曼滤波、主成分回归等化学计量学方法的解析结果进行了比较,表明神经网络方法优于其它方法。使用改进的ＢＰ算法,避免了神经网络学习过程中可能产生的麻痹现象。提出了目标向量的简单变换方法及便于网络参数选择的收敛评价函数。     

Mechanism of synergistic extraction of rhenium(VII) by primary amines and neutral phosphorus esters

It has been found in the present study that Re(VII) can be quantitatively separated from Mo(VI) in alkaline solutions by synergistic extraction with primary amine and neutral phosphorus esters. The mechanism of synergistic extraction was studied. Results of extraction with combinations of different donor and acceptor solvents indicated that during extraction hydrogen bonds were formed between perrhenic acid and active hydrogen atoms of primary amines as well as between the acid and active phosphoryl oxygen of neutral phosphorus esters. The composition of the synergistic extraction adduct was studied and its structure was also proposed. This newly found extraction system is important to the extraction and separation of Re(VII) and also to the studies of mechanism of synergistic extraction.