共查询到20条相似文献,搜索用时 78 毫秒
1.
为提高煤、煤矸石和粉煤灰中总锗的测定速度,减少有机萃取剂用量,通过优化仪器工作条件,采用混合酸消解样品、蠕动进样、屏蔽式点火等方法,研究了PISI-AFS法测定煤、煤矸石和粉煤灰中微量锗含量的准确度和精密度。结果表明,该方法检出限为0.0425μg/g,相对标准偏差RSD为1.42%,标准工作曲线的线性范围达到1~400 ng/g,锗的加标回收率为98.92%~103.79%。该法与GB/T 8207—2007中的蒸馏分离-苯芴酮分光光度法的测定值的相对误差小于5%。离子干扰试验中,该法测定值的相对误差未超过±5%,说明PISI-AFS法适用于定量测定煤、煤矸石和粉煤灰中微量锗,准确度和精密度均较高。 相似文献
2.
《洁净煤技术》2015,(5)
为实现煤中多种微量元素的批量快速测定,煤样经高温灰化、盐酸-氢氟酸-高氯酸三元体系溶解、盐酸提取后,使用电感耦合等离子体发射光谱(ICP-OES)同时测定煤中镓钍钒磷铜钴镍锌铅铬镉11种微量元素。在对样品分解方法、射频功率、分析谱线和积分点数合理选择的基础上,通过离峰扣背景法消除了各种光谱干扰对测定的影响,建立了采用ICP-OES同时测定煤中镓钍钒磷铜钴镍锌铅铬镉11种微量元素的实验方法。方法检出限为0.03~1.17μg/g,方法精密度(n=11)0.32%~3.19%,土壤国家标准物质的分析测定值与标准值吻合较好。与传统化学方法相比,该方法快速准确,提高了分析效率,满足煤质分析的一般要求。 相似文献
3.
为准确快速地检测铜尾矿中的铜铅锌银,选择电感耦合等离子体原子发射光谱仪(ICP-OES)对其进行测定,对实验条件、方法检出限、精密度和加标回收率做了研究。铜尾矿样品经氢氟酸-盐酸-硝酸分解后,用ICP-OES同时测定铜铅锌银4种元素,方法的检出限为0.000 62~0.003 5μg·m L-1,精密度为0.67%~3.08%,回收率为90.0%~110.0%。 相似文献
4.
采用HNO3-HF-HClO4湿法消解法、HNO3-HF-HClO4微波消解法、钠系碱法消解法和偏硼酸锂融熔法分别处理粉煤灰标准品和某电厂粉煤灰样品,利用ICP-OES法测定各组样品中K、Na、Ca、Mg、Al、Fe、Si 7种元素的含量,对比4种前处理方法的优劣势,探讨简单、快捷、准确的测定粉煤灰中矿物质元素的前处理方法。研究表明,HNO3-HF-HClO4湿法消解法的回收率范围为101. 00%~118. 20%,标准偏差(RSD)1. 49%; HNO3-HF-HClO4微波消解法的回收率范围为103. 00%~109. 80%,标准偏差(RSD)1. 58%;钠系碱法消解法的回收率范围为102. 34%~108. 61%,标准偏差(RSD)1. 62%;偏硼酸锂融熔法的回收率范围为103. 20%~109. 30%,标准偏差(RSD)1. 68%。4种方法均具有较好的准确度和精密度,但HNO3-HF-HClO4湿法消解法测得的元素含量平均值普遍偏低。所以综合考虑,偏硼酸锂融熔法操作简单、耗时短,与湿法消解法相比,可以避免使用大量酸造成对设备腐蚀和环境污染;与钠系碱法消解法相比,可以避免对K、Na元素的电离效应和基体影响。因而,偏硼酸锂熔融法可作为测定粉煤灰矿物质元素含量较好的前处理方法。 相似文献
5.
建立工业级己二酸中多个无机杂质元素的快速光谱分析方法。己二酸样品经硝酸溶解后直接用电感耦合等离子体发射光谱(ICP-OES)法测定其中的Na、Mg、Al、K、Ca、V、Cr、Mn、Fe、Cu、Zn、Pb等12种无机杂质元素。通过优化仪器工作参数,选择最佳的分析波长,并以Y为内标元素消除了测定过程中的光谱干扰和基体效应。在优化的实验条件下,方法的检出限为0.56~18.20μg·L-1,各元素的加标回收率为92.96%~107.90%,RSD为0.8%~3.3%。方法可实现工业级己二酸中无机杂质元素的快速准确测定。 相似文献
6.
7.
8.
采用X射线荧光光谱法研究伴生放射性地质样品中钛、铀、钍元素的快速测定方法。通过自制标准样品补充并拓宽了各元素的线性范围,探讨样品粒度对测定结果的影响,并进行实际样品和标准物质验证。结果显示,样品粒度应不大于0.097 mm时,经标准物质和实际样品验证,测定结果准确可靠。方法检出限低(Ti 12.35μg/g、U 0.14μg/g、Th 0.12μg/g),准确度好,RSD均小于3%,线性范围宽,简便快速,能实现伴生放射性地质样品中钛、铀、钍元素的快速准确测定。 相似文献
9.
建立了ICP-OES法测定碱石灰中氢氧化钠的含量,通过直接测定样品中的钠元素含量,间接计算获得氢氧化钠的准确含量。样品经硝酸溶液超声溶解过滤后,直接上机分析,外标法定量。结果表明:目标物钠元素在0.051~20.0 mg/L范围内线性关系良好(r=0.999 8),对测试过程中的钠元素分析谱线进行考察,幵对方法的检出限、精密度以及加标回收率进行了试验确认。结果表明方法检出限为0.049g/kg,实际样品重复检测的相对标准偏差为4.1%,加标回收率在94.5%~102%,均满足法规要求。该方法具有前处理简单、干扰少、测定快速、结果准确等优点,可用于碱石灰中氢氧化钠的测定。 相似文献
10.
11.
12.
M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria. 相似文献
13.
Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively.
There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized.
High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without
the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of
fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to
achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic
SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve
F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender
particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing,
and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing
or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually
preserves suspension stability during freezing.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago,
IL. Tied for first place in The John A. Gordon Best Paper Competition. 相似文献
14.
Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae
and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted
in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures
(release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species
(Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species
to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were
exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of
separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles
from the southeastern region of the US. 相似文献
15.
16.
17.
18.
Peter A. Edwards Grant Striemer Dean C. Webster 《Journal of Coatings Technology and Research》2005,2(7):517-527
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins.
Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol.
The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and
cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on
the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to
determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model
amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate
functional group is more reactive than a glycidyl ether group.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago,
IL. 相似文献
19.
Dongjiang Yang Yao Xu Lei Zhang Shangru Zhai Dong Wu Yuhan Sun 《Journal of Coatings Technology and Research》2006,3(2):127-131
A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by 1H MAS NMR. For direct comparison purposes, an SiO2 coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N2 absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals. 相似文献
20.
Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed. 相似文献