几种蔬菜中亚硝酸盐含量的测定

用盐酸萘乙二胺比色法分别测定10种蔬菜中亚硝酸盐的含量,结果表明,在λ=538nm处,该络合物具有最大吸光度,在0～1μg·mL-1范围内,亚硝酸盐含量x(μg)与吸光度A之间具有良好的线性关系,其线性方程为y=0.0282x+0.0015,相关系数r=0.9997.从测定的芫荽等10种蔬菜当中,亚硝酸含量最高的为茄子...     

荧光分析法测定芒果叶总黄酮含量的研究

采用荧光分析法测定芒果叶中总黄酮含量。根据Al3+与黄酮类化合物形成稳定的荧光络合物,以芦丁为标样,采用低共熔溶剂作为提取溶剂,对芒果叶总黄酮进行微波辅助提取,选择激发波长λex=436 nm、发射波长λem=483 nm条件下,测定四种品种的芒果叶中总黄酮含量。该方法检测限为0.12μg/m L,线性范围在0.16~0.80μg/m L之间,线性方程为:y=11.41+1789.2x,线性相关系数为r=0.9989,回收率为97.2%~102.5%,相对标准差(RSD)为1.39%。荧光分光光度法测定芒果叶中总黄酮含量准确度较高,操作简便,成本低。     

HPLC法测定木鳖子中对羟基苯甲酸含量

采用HPLC法测定木鳖子中对羟基苯甲酸含量。色谱条件为:Agela Venusil XBP C18色谱柱(4.6 mm×250 mm,5μm),甲醇-0.1%乙酸为流动相进行梯度洗脱,检测波长254 nm,流速1 mL·min~(-1)。结果表明,木鳖子中对羟基苯甲酸分离良好,分离度为1.75,理论塔板数为126 964;对羟基苯甲酸质量(x)在0.100～0.485μg之间与峰面积(y)线性关系良好,线性方程为y=1000000x-81274(R~2=0.9997);平均加标回收率为107.5%;木鳖子药材中对羟基苯甲酸含量为4.942μg·g~(-1)。该方法简单、高效,可用于木鳖子中对羟基苯甲酸含量测定。     

HPLC测定不同干燥方法亳菊中5种成分的含量

通过高效液相色谱法建立测定不同干燥方法亳菊中绿原酸、3,5-O-二咖啡酰基奎宁酸、木犀草素、木犀草苷和金合欢素的含量的方法。采用菲罗门C18色谱柱(4.6 mm×250 mm,5μm),乙腈-0.1%磷酸水为流动相,梯度洗脱,流速:1.0m L·min~(-1),检测波长325 nm,柱温30℃。绿原酸41.50~0.83×103μg·m L~(-1)木犀草苷2.45~122.50μg·m L~(-1)、3,5-O-二咖啡酰基奎宁酸15.78~1.58×103μg·m L~(-1)、木犀草素327.33~1.96×103μg·m L~(-1)、金合欢素7.62~762μg·m L~(-1)浓度范围内呈良好线性关系,回归方程分别为y=3.3257x-10.6227(r=1.0000)、y=0.9865x+0.1356(r=1.0000)、y=3.6681x-27.6275(r=0.9999)、y=1.2538x-4.3563(r=1.0000)和y=3.6216x-1.2515(r=1.0000)。加样回收率分别为97.97%、97.49%、97.79%、98.27%、98.90%,RSD均小于5%。该方法快速,简便,重复性好,适合于同时测定亳菊中绿原酸、3,5-O-二咖啡酰基奎宁酸、木犀草素、木犀草苷和金合欢素的含量。     

紫外分光光度法阿司匹林肠溶片中阿司匹林的含量测定

文章研究采用紫外分光光度法测定阿司匹林含量。阿司匹林在在276 nm波长处有最大吸收峰,在40~120μg/m L浓度范围内线性关系良好,回归方程为y=0.0059x+0.0206,R2=0.9992(n=5)。稳定性试验RSD为0.65%,精密度试验RSD为0.34%,回收率试验,平均回收率为101.1%,RSD为1.47%。准确度在允许范围内,故本法适用于阿司匹林肠溶片中阿司匹林含量的测定。     

HPLC法检测蔬菜中的阿维菌素

建立了测定蔬菜样品中的阿维菌素含量的HPLC法。检测波长为245 nm,阿维菌素浓度在0.01~10μg/m L范围内呈良好的线性关系,线性回归方程:y=8343x+2621,相关系数为0.9997,检出限为0.01μg/m L,回收率在85.06%~99.91%之间,RSD为1.65%~2.82%。该方法准确度高,重现性好,灵敏快速,操作简便,可满足蔬菜中阿维菌素残留的检测要求。     

铁(Ⅲ)-硫氰酸钾体系褪色光度法测定硫普罗宁含量

酸性介质中,铁(Ⅲ)与硫氰酸钾生成最大吸收波长为445nm的血红色配合物,加入的硫普罗宁将溶液中的Fe(Ⅲ)还原为Fe(Ⅱ),导致溶液吸光度减小。测定配合物溶液与硫普罗宁反应前后的吸光度记为A0、A,吸光度变化值ΔA=A0-A。结果表明,加入的硫普罗宁浓度c(x/mg·m L~(-1))在0~0.14 mg·m L~(-1)范围内,与ΔA(y)有良好的线性关系,其线性回归方程为y=0.8149x+0.0006,线性相关系数r=0.9997。方法用于硫普罗宁肠溶片中硫普罗宁含量的测定,结果与国家药品标准测定结果相近,有一定的应用价值。     

HPLC测双氯芬酸钾干混悬剂的含量

建立了高效液相色谱法测定双氯芬酸钾干混悬剂含量的测定方法。色谱柱为Kromasil C18(250 mm×4.6 mm,2.5μm),流动相:甲醇-水-冰醋酸(80∶20∶0.8,V∶V∶V),检测波长为276 nm,流速为1.0 m L·min-1,进样量为20μL。结果表明:y=40999x+119667(r=0.9995,n=7)线性范围为4.0~6.0μg·m L-1;最低检测限为1.66 ng,定量限为5.56 ng;平均回收率为99.57%。该方法简便、准确、适用于双氯芬酸钾干混悬剂的含量测定。     

高效液相色谱法测定奶嘴中双酚A的含量

采用高效液相色谱法,测定各种品牌奶嘴中的双酚A含量。通过调整色谱条件对检测结果的影响,得出最佳的色谱条件为:甲醇/水(V/V=80:20)作为流动相,流速为0.8m L/min,检测波长为280nm,进样量为20μL。在此优化条件下,采用系列浓度的双酚A标准溶液,绘制其标准曲线,结果显示在1.0~20.0μg/m L范围内线性关系良好,线性方程为y=4816.3x+5322.5,相关系数R2为0.99993,相对标准偏差RSD(n=11)为0.12%,检出限(S/N=3)为0.36μg/m L。将这个方法用在奶嘴中的双酚A的测定,回收率可达85.5%~105%。     

紫外分光光度法测定桃金娘果油脂中熊果酸的含量

建立测定桃金娘果油脂中熊果酸含量的方法。香草醛乙酸溶液和高氯酸为显色体系,采用紫外分光光度法,在最大波长吸光度546 nm下测定熊果酸的含量。结果表明熊果酸质量在10~100μg范围内与吸光度呈良好的线性关系,线性回归方程为:y=0.0107x+0.101(R~2=0.9990)。实验方法简便可靠,精密性好、回收率高,适用于桃金娘果油脂中熊果酸含量的测定。     

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。