极谱测定苯胺中微量硝基苯的方法研究

通过正交实验和验证实验确定极谱测定苯胺中微量硝基苯的最佳条件,同时对悬汞电极、静态滴汞电极、滴汞电极等3种电极模式以及微分脉冲极谱和经典直流极谱2种极谱类型进行了实验比较,得出相应的结论。     

氟伐他汀钠的电化学行为和测定

研究了在pH值为5.10的醋酸-醋酸钠缓冲液中,氟伐他汀钠在玻碳电极上的电化学行为,并依此建立了氟伐他汀钠的微分脉冲伏安测定法。在微分脉冲伏安模式下,于 0.64 V(vs.Ag/AgCl)电位处产生一灵敏的阳极氧化峰,用循环伏安法、线性扫描极谱法、微分脉冲伏安法等手段研究了其电化学行为和机理。结果表明,该峰电流值与氟伐他汀钠的质量浓度在2.0~40 mg/L范围内呈良好的线性关系,其最低检测限为0.24 mg/L,该法应用于来适可胶囊中氟伐他汀钠含量的测定,回收率达到98.0%~101.2%,并讨论了氟伐他汀钠在玻碳电极上的电极过程。     

微机化多功能电分析仪测定农药杀菌剂三环唑

报道了农药杀菌剂三环唑有效体的脉冲极谱测定新方法。三环唑硝化产物的极谱波在磷酸缓冲溶液中 (Na3 PO4 H3 BO3 NaOH) ,其峰电位Ep =-0 .5 5V (Ag/AgCl电极 ) ,其浓度和峰高在 :1× 10 - 5mol/L～ 3.4×10 - 5mol/L时线性关系良好 ,利用该法测定了粉剂中的三环唑 ,其结果与GLC法吻合。另外 ,对极谱电极反应机理进行了较详细的论证 ,实验结果与理论推导一致性很好。     

离子液体-石墨烯修饰碳纤维微电极电化学研究

实验制备了离子液体-石墨烯修饰碳纤维微电极,采用循环伏安法和差分脉冲伏安法测定对乙酰氨基酚(ACOP)在该修饰电极上的电化学行为。结果显示,修饰后电极的稳定性和重现性明显增加。ACOP在修饰电极上的氧化峰电流与扫速的平方根基本成正比,氧化过程受扩散控制。采用差分脉冲伏安法测定ACOP标准品梯度浓度溶液,在5×10-7~1×10-4mol/L浓度范围内,其氧化峰电流与其浓度呈现良好的线性关系良好。     

极谱法测定金矿石中的砷

在氢氧化钠-硼砂的底液体系中对金矿石进行极谱测定,在峰电位-0.35 V,砷的质量浓度在2～400μg/mL之间时砷的浓度与峰电流成线性关系。选用含有甘露醇的氢氧化钠硼砂的底液测定砷,精度好,准确度高,检出限为0.002μg/mL。     

示差脉冲极谱法测定柠檬黄

建立了示差脉冲极谱法测定饮料中的合成色素柠檬黄的新方法。在pH 6.00的磷酸盐缓冲溶液中,柠檬黄在-0.59 V处产生一灵敏的还原峰,在1.25×10-6～4.37×10-5 mol/L浓度范围内,其峰电流与浓度呈线性关系,线性回归方程为ip（μA）=2.46×106 c（mol/L）＋11.4（相关系数r=0.970）,实验检出限为0.27μg/mL。利用该方法测定了两种市售饮料中柠檬黄,加标回收率在87.5%～109.6%之间。     

离子液体中的相互作用对硝基苯扩散系数的影响

应用紫外吸收光谱法和循环伏安法研究了离子液体中的相互作用及对离子液体中硝基苯的扩散系数的影响。结果表明,硝基苯的紫外光谱受离子液体EMimBF₄(1-甲基-3-乙基咪唑四氟硼酸盐)与其相互作用的影响,硝基的吸收峰红移,210 nm以下的末端吸收消失,而苯环的吸收基本不变;离子液体与硝基苯之间的作用主要发生在硝基上。在离子液体中电还原,硝基苯的扩散系数受硝基苯与离子液体、水与离子液体的相互作用的影响。同一离子液体中,随硝基苯浓度增加,扩散系数减小。相同硝基苯浓度时,不同离子液体的咪唑阳离子侧链越长扩散系数越小,但扩散系数减小得越缓慢;同一离子液体中,随着水浓度增加,硝基苯扩散系数增大;不同离子液体中,咪唑侧链越长,随着水的浓度增加,硝基苯扩散系数增加越快。     

多菌灵在多壁碳纳米管-聚4-(2-吡啶偶氮)间苯二酚膜修饰电极上的电化学行为及测定

制备了多壁碳纳米管-聚4-(2-吡啶偶氮)间苯二酚膜修饰电极,利用扫描电镜对新的复合膜修饰电极(PAR-MWNT/GCE)进行表征,研究了在多菌灵的循环伏安曲线以及它的差分脉冲伏安曲线。结果表明,该修饰电极对多菌灵具有良好的电催化作用。在8.0×10-6~2.06×10-4 mol/L浓度范围内,多菌灵的差分脉冲伏安法的峰电流和浓度呈现良好的线性关系,相关系数为0.997 11,检出限为2.5×10-7 mol/L(S/N=3)。PAR-MWNT/GCE复合物修饰电极可快速、简洁、方便的测定多菌灵的浓度。     

基于铍试剂Ⅲ二阶导数极谱法测定壳聚糖含量

在pH 3.5的六次甲基四胺-盐酸缓冲溶液中,铍试剂Ⅲ在峰电位-0.318V(vs.SCE)处能产生一灵敏尖锐的二阶导数极谱波,当在体系中加入一定量的壳聚糖时,该二阶导数极谱波峰电流会降低,在选定的最佳条件下,其峰电流的降低值与加入的壳聚糖的质量浓度在0.5～6mg/L的范围内呈线性关系,线性回归方程为Δip=-4.06+84.89c,相关系数r=0.997 1,检出限0.4mg/L。     

二元离子液体OMImBF4/HMImPF6中硝基苯的电化学还原

将离子液体OMImBF₄与HMImPF₆二元复合,研究了离子液体复合前后电导率、红外谱峰等的变化,在不同体积比的OMImBF₄/HMImPF₆体系中采用循环伏安法(CV)、计时电流法(CA)和电化学原位红外光谱法(In-situ FTIRS)等方法探究了硝基苯在铂电极上的电化学还原行为。研究结果表明,OMImBF₄/HMImPF₆的电导率随HMImPF₆体积比的增大而减小,红外谱峰较单一离子液体变化明显;硝基苯在体积比为3:1的二元离子液体OMImBF₄/HMImPF₆体系中的还原峰电位及还原峰电流均优于单一离子液体,且主要产物偶氮苯的选择性及硝基苯的转化率都要优于单一离子液体。硝基苯在此二元离子液体体系中的还原过程受扩散控制,扩散系数D为 2.024×10^-7 cm²·s^-1。     

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。