共查询到20条相似文献,搜索用时 437 毫秒
1.
2.
流动注射在线离子交换预富集—氢化物发生原子荧光光谱法测定痕量… 总被引:3,自引:1,他引:2
研究了流动注射液在线离子交换预富集及在线氢化物发生法与原子荧光光谱法的联用技术,设计了双柱交替正向富集和反向洗脱的在线离了交换流路系统。在采样频率为30次/h下,灵敏度较常流动注射氢化物发生原子荧光光谱法提高了11倍,应用于环境水样痕量碲的分析,获得了满意的结果。 相似文献
3.
碱性体系在线氢化物发生—原子荧光光谱法测定痕量铋 总被引:4,自引:0,他引:4
提出了一种碱性体系在线氢化物发生-原子荧光光谱法测定痕量铋的分析方法。设计了在线氢化物发生系统流路及操作程序,研究了碱性体系氢化物发生的各项最佳条件。方法操作简便快速,能有效地消除过渡元素的严重化学干扰。应用于黄铜标样中痕量铋的直接测定,获得满意结果。 相似文献
4.
《理化检验(化学分册)》2015,(4)
综述了砷的提取、分离和检测方法的研究进展。主要包括超声提取法、微波辅助提取法、固相萃取法等常用的提取方式;分别用于水样和海产品中砷的富集的共沉淀法和毛细管电泳法;以及高效液相色谱-电感耦合等离子体-质谱法、高效液相色谱-氢化物发生-原子吸收光谱法、氢化物发生-电感耦合等离子体-原子发射光谱法等用于砷形态分析的分离和检测方法(引用文献56篇)。 相似文献
5.
二乙基二硫代氨甲酸银体系流动注射法测定砷 总被引:1,自引:0,他引:1
本文设计了一种AgDDC流动注射-分光光度法测定砷的系统。该系统采用自制的氢化物发生及吸装置,将液体流路和载气流路结合在一起。 相似文献
6.
连续氢化物发生端视ICP-AES法测定水中痕量硒和汞 总被引:11,自引:0,他引:11
报道了用自制的在线氢化物连续发生装置,应用端视ICP-AES法测定水中痕量硒和汞。不需要专用氢化物发生装置,分析成本低。在完成非氢化法测定或氢化法测定时不需拆卸或安装。方法简便、快速。测定水中硒和汞的测定,其检出限分别为2×10-4和1×10-4mg·L-1。 相似文献
7.
8.
9.
10.
氢化物发生石墨炉原子吸收进展 总被引:1,自引:0,他引:1
在氢化物发生原子吸收光谱中,石英管是使用较为广泛的原子化器,但由于其气相干扰比较严重,石英管表面性质对分析灵敏度影响较大,因而又发展了石墨炉原子化器。自提出涂钯石墨管原位富集氢化物以后,氢化物发生石墨炉原子吸收受到人们的重视。现将氢化物发生石墨炉原于吸收的主要方法分述如下: 1 石墨炉在线原子化法 所谓石墨炉在线原子化法,是将生成的氢化物直接通入已经达到原子化温度的石墨管里的方法。氢化物可以从石墨炉内气路通入石墨管,也可以从石墨管进样孔进入石墨管。由于石墨炉原子化的温度较高,因而能大大减小可以形成氢化物元素的气相干扰。文献[1]比较了石英管和石墨管两种原子化器的抗干扰能力,其中有关砷和硒的干扰情况见表1。 相似文献
11.
KHAN MUHAMMAD ASHRAF ZENG XIANCHENG WANG QIAN TIAN ANMIN 《Journal of Dispersion Science and Technology》2013,34(4):389-406
Acrylamide is conveniendy polymerized in aqueous solution lo a water soluble polymer. The measurements of kinetic parameters of polymerization of acrylamide, in aqueous and micellar solution, have been earned out by conduction calorimeter. The polymerization is initiated by sodium sulfite and sulfite-persulfate redox system. The effect of initiator and monomer concentration as well as temperature and surfactants on polymerization rale constant has been investigated. The analog thermogram method has been employed to calculate the rate constants. The activation energy is calculated from Arrhenius relationship and molecular weights are determined by viscometry. Rate equations have been derived and reaction mechanism hove been suggested. The rate of reaction is found to increase with temperature and monomer concentration. 相似文献
12.
13.
原子吸收法测定植物中微量金属元素 总被引:14,自引:3,他引:11
探讨了一种快捷有样品预处理方法,即采用取四氟乙烯高压罐微波消化法处理样品。通过正交试验分析得到较优的消化条件,并在此条件下做锌、铁、锰的加标回收试验,得回收率分别为97.0%、94.3%、90.6%,相对标准偏差1.2%、4.1%,3.4%。另外,还做了扩展试验,与国标法对照的试验。通过试验和比较,证实该消化方法具有安全、省时、方便等优点。 相似文献
14.
The dye-sensitized photooxygenation of t -butyl substituted catechols has been investigated. The primary product from 3,5-di- t -butyl catechol has been isolated and shown to be a hydroperoxydienone by single crystal X-ray diffraction. The absence of sensitizer effects and the faster reaction rate in polar solvents suggest that the reaction proceeds with singlet oxygen as the primary oxygenating species. Charge-transfer or full electron-transfer from the catechol to singlet oxygen is probably involved. Substituent effects are in agreement with this mechanism. The products from thermal breakdown of the hydroperoxydienone are inconsistent with a Baeyer-Villiger mechanism. 相似文献
15.
煤中微量元素间依存关系的聚类分析 总被引:9,自引:2,他引:9
通过对四种不同类型煤中灰分、硫分和16种微量在不同密度级中呈的R型聚类分析,研究了煤中微量元素间的依存关系。结果表明:煤中碱土 金属Be、Sr、Ba彼此间的依存关系一般较弱,与所研究的其它元素的相关性也较北:稀土元素La、Ce、Y、Se经常相伴而生;V总与灰分显著相关;As、Co、Ni等元素民黄铁矿硫的存在密切相关。 相似文献
16.
17.
CaO固硫反应机理研究的新进展 总被引:7,自引:5,他引:7
CaO固硫反应的机理研究一直是高温钙基固硫的难点,最近研究认为CaO固硫反应分为两个阶段:前期为表面化学反应阶段,后期为产物层扩散控制阶段。前期反应生成的CaSO4不仅堵塞了CaO颗粒之间的微孔,也逐渐包覆了CaO颗粒,致使后阶段固硫反应转化率明显降低。传统上认为是SO2和O2通过CaSO4产物层向内扩散与CaO进行反应,依此机理提出了核收缩模型和等效粒子模型。新的研究结果认为,固硫反应后期的产物层扩散控制阶段,主要发生的反应是Ca2+通过产物层CaSO4扩散至表面与SO2和O2进行反应,而与传统的机理不同。本文主要介绍了两种实验技术在CaO固硫机理研究中的应用,并在实验现象基础上,对固硫机理提出了新认识。最后对在CaO中添加了不同添加剂能明显提高固硫率的试验数据作了新的机理解释。 相似文献
18.
Abstract— The excited states of bilirubin (BR) in a variety of environments have been studied by 347 nm laser flash photolysis. Quantum yields of formation of triplet BR have been shown to be less than 0.005 in solution in water ( p H 9–11), methanolic ammonia, 10% aqueous mulgofen and in cetyl trimethyl-ammonium bromide. In benzene the quantum yield was 0.01 although this diminished to less than 0.005 on addition of triethylamine. Permanent products are formed with benzene and with 1% methanolic ammonia. With BR in HSA a transient decaying with k = 3.5 × 105 s-1 is formed by a monophotonic process together with a permanent product. Neither species is affected by oxygen or by iodide ion. Both originate from BR molecules in the strongest binding site in the HSA. The yields of both species are unaffected by salt but are temperature dependent. The decay of the transient is strongly temperature dependent corresponding to an activation energy of about 50–60 kj mol-1 . If this transient is a triplet it is formed with a quantum yield of 0.13 ± 0.01. The relevance of these results to an understanding of the photo therapeutic process is discussed. 相似文献
19.
Abstract— The pathways and quantum yields of direct photoisomerization of unprotonated and pro-tonated n-butylamine Schiff bases (SB and PSB) of isomeric retinylideneacetaldehyde (C22 aldehyde) were determined in n-hexane, acetonitrile and methanol for the former and in acetonitrile and methanol for the latter. The results are compared with those of the Schiff bases of isomeric retinal (C20 SB and C20 PSB) reported previously (Koyama et al., Photochem. Photobiol. 54 , 433–443, 1991). The isomerization pathways and quantum yields of C22 SB are more or less similar to those of C20 SB, but conspicuous differences in the isomerization pathways are found between C22 PSB and C20 PSB. The homogeneous (exclusive) isomerization of the retinylidene chromophore from all-trum to 11-cis in retinochrome is rationalized not by C22 PSB but by C20 PSB.
Almost complete one-way isomerization from cis to trans of C22 SB (in n-hexane) is ascribed to isomerization via the T1 state, while mutual isomeritation between cis and tram of C22 PSB is ascribed to isomerization via the S1 (Bu ) state. The TI potential of C22 SB and the S1 potential of C22 PSB are discussed based on photostationary state compositions. 相似文献
Almost complete one-way isomerization from cis to trans of C22 SB (in n-hexane) is ascribed to isomerization via the T
20.
MODE OF COACTION OF PHYTOCHROME AND BLUE LIGHT PHOTORECEPTOR IN CONTROL OF HYPOCOTYL ELONGATION 总被引:4,自引:0,他引:4
Abstract The rate of hypocotyl longitudinal growth in seedlings of Sesamum indicum L. is strongly inhibited by continuous blue light (cBL)† and slightly by continuous far-red light while continuous red light (cRL) or red light pulses are hardly effective from 60 h after sowing onwards. Between 36 and 60 h after sowing the growth rate responds to red light pulses the effect of which is fully reversible by long wavelength far-red light. When seedlings are kept in cBL for 3 days and then treated with red light hypocotyl growth rate responds strongly. However, RL effectiveness decreases with time after transfer from BL to RL. BL → darkness transfer experiments with different levels of Pfr established at the beginning of darkness show that after a BL pretreatment phytochrome (Pfr ) alone is capable of fully controlling growth rate. When white light (WL) is given no BL effect is detectable in weak WL. Only high light fluxes maintain a typical BL growth rate. At medium WL fluxes elongation rate returns gradually to the dark rate. The simplest explanation of the data is that light absorbed by a separate BL photoreceptor is necessary to maintain responsivity to Pfr . With increasing age of the seedlings the requirement for BL increases strongly. On the other hand, brief light pulses—given to demonstrate photoreversibility of phytochrome—remain equally effective provided that responsivity to Pfr exists. 相似文献