反相高效液相色谱法分离测定生孢乳杆菌发酵液中的乳酸

采用反相高效液相色谱法测定了生孢乳杆菌发酵液中的乳酸.在EclipseXDB-C8,(4.6 mm i.d.×150 mm,5 μm)色谱柱上,以0.005 mol/L硫酸(pH值2.5)溶液作流动相,流速为1 mL/min,以示差折光检测器检测信号,峰面积(Y)与乳酸的质量浓度(X,g/L)的线性相关方程为Y=292.08x+4.6967,线性相关系数r为0.999 9,线性范围为0.75～9.0g/L,检测限为0.2μg(3倍信噪比).结果表明,实验方法简便、快速、可靠,精密度为0.22%(n=5),回收率99%以上.     

离子色谱测定硫酸二甲酯中亚硫酸二甲酯含量

将硫酸二甲酯用氢氧化钠水溶液处理,采用配有电导检测器的离子色谱检测.色谱条件:IonpacA22色谱柱;流动相4.5mmol/L Na2CO3+ 1.4 mmol/L NaHCO3;流速1.00mL/min;柱温25C.结果表明,在此条件下,亚硫酸二甲酯在0～6.0mg/L与相应的峰面积具有良好的线性关系(R=0.9997)线性回归方程为y=16.24×+ 6.4回收率87.59％～95.73％.     

高效液相色谱法分析甲基丙烯酰氧乙基三甲基氯化铵中的阻聚剂

利用反相高效液相色谱法 (HPLC) ,采用ExtendC18柱、以甲醇 -水 ( 0 .0 5 %高氯酸 )为流动相 (体积比为 5 5 :45 ) ,二极管阵列检测器对甲基丙烯酰氧乙基三甲基氯化铵 (简称DMC)中的阻聚剂对羟基苯甲醚进行了检测。试验结果证明 ,对羟基苯甲醚在0 .0 2mg/mL～ 2mg/mL浓度范围内与峰面积呈良好的线性关系。方法回收率为 98.9%～ 10 1.6% ,相对标准偏差为 1.3 2 % ,最低检测限为 5× 10 - 4mg/mL。     

苯哒嗪钾关键中间体氯苯哒嗪甲酯的高效液相色谱分析

建立测定苯哒嗪钾关键中间体氯苯哒嗪甲酯含量的高效液相色谱法.采用Kromasil C8色谱柱,以乙腈-水(体积比50:50)为流动相,检测波长274 nm,流速1.0 mL/min.方法的线性范围为30.0～70.0 mg/L(相关系数为0.9996),最低检测限为0.09 mg/L,定量限为0.3 mg/L,回收率在98.0%～100%之间,相对标准偏差为0.37%～1.56%.     

氟蚁腙的高效液相色谱分析

建立了反相高效液相色谱测定氟蚁腙原药的分析方法. 色谱柱为Hypersil ODS 柱;流动相为乙腈-三乙胺水溶液(体积比85∶15),流速1.2 mL/min ;紫外检测波长295 nm ;柱温30 ℃;氟蚁腙的质量浓度为24.38～390.04 mg/L时,峰面积与质量浓度具有良好的线性关系,相关系数为0.998. 方法的检出限(S/N≥3)为0.01 mg/L,相对标准偏差(RSD)为0.30,平均回收率为99.8%.     

花生中乙草胺残留的免疫亲和柱净化-高效液相色谱分析

建立了免疫亲和柱净化-高效液相色谱 -紫外检测器测定花生中乙草胺含量的方法. 样品经过纯甲醇提取浓缩,用含有乙草胺抗体的免疫亲和柱(IAC)净化,甲醇洗脱. 以C18柱为分离柱,乙腈-水(体积比75∶25,pH值3)为流动相对洗脱液进行高效液相色谱分离及紫外检测,紫外检测波长为215 nm. 结果表明:乙草胺IAC柱的吸附容量为0.556 mg;仪器的检测限为15 mg/L,方法检测限为3 mg/L;乙草胺的质量浓度为20～500 mg/L时与峰面积呈良好的线性关系,相关系数为0.9969;在5～50 mg/kg添加水平下,经过IAC柱浓缩净化提取物,测得回收率在94.06%～102.5%之间,变异系数在2.55%～7.95%之间.     

反相高效液相色谱法分离测定产琥珀酸放线杆菌发酵液中的琥珀酸

采用反相高效液相色谱法测定了产琥珀酸放线杆菌发酵液中的琥珀酸.在EclipseXDB-C8(4.6 mm i.d.×150 mm,5μm)色谱柱上,以0.005 mol/L硫酸(pH值2.5)溶液做流动相,流速为1 mL/min,示差折光检测器检测信号.峰面积(Y)与乳酸的质量浓度(X,g/L)的线性相关方程为Y=151.1x-0.666 1,线性相关系数r为0.999 9,线性范围为2.0～10.0g/L,检测限为0.9(μ)g(3倍信噪比).结果表明,实验方法简便、快速、可靠,精密度为0.22%(n=5),回收率99%以上.     

反相高效液相色谱法测定碱性橙Ⅱ

运用HPLC法对食品中非法添加剂的碱性橙II的定量定性的分析,并对方法进行优化。结果表明:用C18色谱柱,流动相为乙腈-0.02mol/L的乙酸铵,流速为1mL/min,定性检测限为0.02mg/L,定量检测限为0.07mg/L。本方法灵敏度高、重现性好、分析速度快,可为食品质量监控提供技术支持。     

反相高效液相色谱DAD法测定尿囊素及其相关物的含量

为了确定高效液相色谱法测定尿囊素及其相关物含量的方法,采用流动相超声溶解样品,用ZORBAX SB-Aq分离,流动相为A(甲醇与0.2mol/L磷酸水溶液体积比1:9)-B(超纯水),梯度洗脱,在190nm波长下检测,外标法定量,测定尿囊素及其相关物的含量。结果表明:尿素质量浓度在0.2～5mg/mL内呈良好的线性关系,检测限为20μg/mL;甘脲在0.1～2.5mg/mL内呈良好的线性关系,检测限为2μg/mL;缩二脲在0.2～5mg/mL内呈良好的线性关系,检测限为4μg/mL。该方法快速、灵敏、准确,可同时测定尿囊素、尿素、甘脲及缩二脲的含量。     

石化废水中几种常见有机酸的测定

建立了用离子色谱测定石化废水中常见有机酸:乙酸、丙烯酸、环己甲酸、苯甲酸和对甲基苯磺酸的新方法。采用IonPac AS11-HC阴离子色谱柱,淋洗液为30 mmol/L的NaOH水溶液,淋洗液流速1 mL/min,抑制电流75 mA。样品中其他有机物和常规无机阴离子对乙酸、丙烯酸、环己甲酸、苯甲酸和对甲基苯磺酸的测定干扰小。5种有机酸的峰面积检测下限分别为0.024、0.025、0.094、0.075、0.059 mg/L,峰高检测下限分别为0.029、0.007、0.045、0.025、0.070 mg/L;峰面积的相对标准偏差分别为1.2%、1.1%、5.3%、2.7%、3.3%,峰高相对标准偏差分别为1.7%、0.4%、2.8%、1.6%、4.5%。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.