吸附伏安法测定痕量锡

在0.2 mol·L~(-1)硫酸条件下,锡-苯芴酮-溴代十六烷基三甲基铵体系中,络合物在-0.56 V呈现一灵敏络合物吸附波,检测下限为2.0×10~(-10)mol·L~(-1)线性范围为1.0×10~(-9)～1.0×10~(-7)mol·L~(-1),用于罐头食品中微量锡的测定,得到满意结果。     

格氏作图法测定废水中的铅

本文提出一个直接快速测定水体中痕量铅的最佳体系: 0.02 mol·L~(-1)KSCN-0.06 mol·L~(-1)CH_3COONH_4-0.02 mol·L~(-1)CH_3COOH-0.1 mol·L~(-1)NaNO_3-5×10~(-3)mol·L~(-1)KI-30 mg/50 mlVo-4％CH_3COCH_3 在该体系中采用格氏作图法可以检测出几个ppb的铅。将该法用于水体样品测定,获得满意结果,方法灵敏度好,准确度高,尤其适用于复杂水样的测定(包括有色、浑浊水样均能直接测定)。     

核黄素的循环伏安法分析

介绍了在 NH3 · H2 O- NH4 Cl( PH=1 0 )缓冲溶液中的核黄素 (维生素 B2 )循环伏安图 ;核黄素在 - 0 .545V( VS.Ag Cl/Ag)产生一个阴极峰 ;在 - 0 .50 6 V产生一个阳极峰。其波高与核黄素溶液的浓度分别在 6× 1 0 - 7～ 7× 1 0 - 6mol· l- 1和 4× 1 0 - 7～ 8× 1 0 - 6mol· l- 1范围内成线性关系 ,检测限分别为 4× 1 0 - 7mol· l- 1和 2× 1 0 - 7mol· l- 1。     

亚胺基二乙酸树脂对镨的吸附性能及其机理

研究了镨离子在亚胺基二乙酸树脂(D401)上的吸附行为,在pH5.73时吸附最佳。测得静态饱和吸附容量为162mg·g~(-1)(树脂);用0.1～3.0mol·L~(-1)_HCl可定量洗脱;表观速率常数k_(298)=2.96×10~(-5)s~(-1);表观活化能E_a=7.18kJ·mol~()-1;等温吸附服从Freundlich经验式;吸附热力学参数△H=10.4kJ·mol~(-1),△S=45.4J·mol~(-1)·K~(-1),△G=-3.10kJ·mol~()-1;树脂功能基与镨离子的配位摩尔比为3:1;用化学和红外光谱等方法探讨了吸附机理。     

化学修饰碳糊电极对环境水样中微量铅、镉离子的连续电化学测定

报道了用8-羟基喹啉作碳糊电极的修饰剂,测定环境体系中微量铅、镉离子的电化学方法.该电极在KNO3(pH=4.0)中,用吸附溶出伏安法测定Pb2+、Cd2+,在-0.56V(vs,SCE)和-0.84V处有灵敏溶出峰,峰电流与铅的浓度在(3.0×10-8～4.5×10-6)mol/L的范围内呈良好的线性关系,与镉的浓度在(4.0×10-8～3.5×10-6)mol/L的范围内呈良好的线性关系,该方法用于水样中铅、镉的测定,检出限为3.0×10-9mol/L(Pb2+)和5.0×10-9mol/L(Cd2+).     

铋膜玻碳电极阳极溶出伏安法测定异烟肼的研究

研究了异烟肼在铋膜玻碳电极上的电化学行为检测方法。在0.1mol/L pH=4.5的HAc—NaAc缓冲溶液的底液中,通过富集,用铋膜玻碳电极进行阳极溶出伏安法测定异烟肼。异烟肼的阳极峰电位为-1.02V(vs.SCE),峰电流与异烟肼的浓度在1.6×10~(-7)～8.0×10~(-5)mol/L范围内呈良好的线性关系。该方法的检出下限为8.0×10~(-8)mol/L。对异烟肼含量用本法进行了测定,获得了满意的结果。本方法的优点是成本低,操作方便,重现性好以及检测下限低。     

乙二胺四乙酸二钠修饰碳糊电极测定铜(Ⅱ)

制备了乙二胺四乙酸二钠(EDTA)修饰碳糊电极并研究了铜在该电极上的阳极溶出伏安行为,提出了一种测定铜的新方法。实验发现,在pH=3.6的醋酸钠-醋酸缓冲溶液中,铜离子于-500 mV(vs.SCE)处被吸附还原,富集在该修饰电极表面。从-150 mV以120 mV/s的速率正向扫描至200 mV,铜在约90 mV处出现一灵敏的阳极溶出峰。峰电流与铜的浓度在1.0×10-8~2.0×10-6mol/L范围内呈良好的线性关系,检出限为1.0×10-9mol/L。并进行了回收率测试,回收率为93%~105%,相对标准偏差小于4%。     

新显色剂4-(2-吡啶偶氮)-邻苯二酚吸光光度法测定微量Cd(Ⅱ)

研究了新显色剂4-(2-吡啶偶氮)-邻苯二酚(PAPC)与Cd(Ⅱ)的显色反应。在有机溶剂DMF及pH=10.08Na_4B_4O_7-NaOH缓冲溶液中,试剂与Cd(Ⅱ)反应生成稳定的橙色配合物,其最大吸收波长为498nm,表观摩尔吸光系数为4.9×10~5L·mol~(-1)·cm~(-1),镉含量在0～3.5×10~(-6)mol·L~(-1)范围内服从比耳定律,该方法应用于长江水与自来水中微量镉的测定,结果令人满意。     

核黄素(VB2)在液体石蜡碳糊电极上的伏安特性及脉冲伏安法测定

以液体石腊碳糊电极为工作电极,在0.1 mol/L NaCl(pH=2.5)底液中研究VB2的伏安特性.VB2有一对氧化还原峰,峰电位为氧化峰(I)-110 mV/还原峰(Ⅱ)-160 mV,结果表明溶液中VB2的电极过程主要受VB2表面吸附控制.VB2溶液受光照后,增加一对光色素的氧化还原峰,其峰电位为氧化峰(Ⅳ)-220mV/还原峰(Ⅲ)-280 mV.采用微分脉冲伏安法进行VB2的定量分析,线性范围为1×10-5～6.0×10-8moL/L,检测下限为2.00×10-8moL/L.测定复合VB药片中的VB2,RSD为2.1%,回收率为96.8～104%,其结果与药典中标准方法测定结果一致.     

新型荧光钙试剂fura—3的合成及其性质的研究

报道了新型荧光钙试剂 fura-3的详细合成方法,研究了 fura-3及其钙配合物的荧光和紫外光谱的性质。fura-3-Ca~(2+)配合物的不稳定常数为8.97×10~(-9),ε为3.64×10~5L·mol~(-1)·cm~(-1),摩尔比为1:1。检测下限为 10~(-8)mol/L。试剂在大量镁存在下对钙有较好的选择性。     

Insect antifeedant properties of anthranoids from the genusVismia

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.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

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.     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

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.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。