黄磷中硝酸根测定方法的研究

基于硝酸根离子对靛蓝二磺酸钠的裉色反应,建立了一个简单、灵敏、快速、选择性高的黄磷中硝酸根离子测定方法。在６００ｎｍ处硝酸根的浓度在１０～１５ｕｇ／５０ｍｌ范围内与靛蓝二磺酸钠吸光度的减小（△Ａ）呈线笥关系,黄磷用ＣＳ２溶解,硝酸根离子用水反相萃取,结果满意。     

硝酸中微量氯根测定方法探讨

硝酸生产设备为不锈钢材质,氯根存在加速设备腐蚀,化工操作也根据氯根高低判断是否存在化工介质泄漏,为确保硝酸生产装置安全、稳定运行,必须准确测定硝酸中氯根含量。目前氯根测定有硝酸银滴定法[1]、佛尔哈德法[2]、硫氰酸汞分光光度法[3]。本文分别用3种方法测定实际样品与标样进行对比试验,硝酸银滴定法不能准确测定硝酸中微量氯根,佛尔哈德法和氰酸汞分光光度法能准确测定硝酸中微量氯根。     

溴甲酚紫褪色光度法测定食盐中的碘

在磷酸介质中,碘酸根在溴化钾存在下可使溴甲酚紫褪色, 且褪色的程度与碘酸根的量在一定浓度范围内呈线性关系.据此建立了测定微量碘的新方法.碘酸根浓度在0.4～4.4 μg/mL范围内符合比耳定律,检出限1.08×10-3 μg/mL, 方法简单,用于加碘食盐中碘的测定, 结果令人满意.     

磷酸氢二钠中微量氯根的分光光度法测定

氯根的测定,通常是用硝酸银直接滴定1。对于微量氯根的测定又有电位滴定法2及汞量法3。这些方法在测定磷酸氢二钠中微量氯根时,存在着干扰大、费时、滴定误差大等缺点,影响了分析结果的准确性。由于氯化银的稳定性不易掌握,利用分光光度法测定微量氯根的方法未见报道。本文研究了以HNO3为介质在聚乙烯醇作稳定剂的条件下,用分光光度法测定磷酸氢二钠中的微量氯根。实验结果表明,该方法操作简便,稳定性及重现性好,结果可靠,由此建立了测定微量氯根的新方法。1、实验部分1.1　仪器与试剂分光光度计:7230型,上海分析仪器厂。Cl-标准溶液(1.0m…     

依文思蓝褪色光度法测定亚硝酸根

研究亚硝酸根与依文思蓝的褪色反应,建立一个简单、灵敏、选择性高的亚硝酸根的测定方法。采用紫外分光光度法测定不同条件下的吸光度。实验表明,当依文思蓝与NO2-反应后发生颜色变化,在615 nm波长处发生褪色反应,此波长处,吸光度的变化与溶液中NO2-的浓度成正比,其线性范围在0~20μg/25 mL,摩尔吸光系数为ε=1.4×104L/(mol.cm),相关系数为0.9995。方法具有良好的稳定性和选择性;建立了测定亚硝酸根的新方法;用于环境水样中微量NO2-的测定,结果满意。     

靛蓝胭脂红氧化褪色光度法测定海带中碘

在稀硫酸介质中,碘离子对溴酸根离子氧化靛蓝胭脂红的褪色反应有催化作用,据此建立了氧化褪色光度法测定微量碘的方法。该方法的最大吸收波长为610 nm,碘含量在0.2~1.4μg·mL~(-1)范围有良好的线性关系,其回归线性方程为ΔA=0.1397c-0.00596,相关系数R=0.9997,方法的检出限为0.1312μg·mL~(-1),回收率为98.5%~103.3%。该方法主要应用于海带中碘含量的测定,结果令人满意。     

离子膜法工艺二次盐水及淡盐水中微量碘的测定方法

研究用硫氰酸铁-亚硝酸催化动力学分光光度法测定离子膜法烧碱工艺原料盐水中的碘含量,建立了二次盐水和淡盐水中微量碘的测定分析方法。该方法以碘酸钾溶液为标准溶液,标注曲线绘制过程中加入浓度为0.05 mol/L的还原剂亚硫酸钠溶液0.05 mL,将碘酸根还原为I~-;I~-在有适量亚硝酸存在的稀硝酸溶液中催化硫氰酸铁溶液令其褪色,并且,在一定范围内,碘含量与反应褪色的程度呈线性关系。碘标准工作曲线的线性相关系数可达0.999 4,检出限≤0.27μg/L(质量浓度,下同),测定下限≤0.81μg/L。对生产工艺中二次盐水和淡盐水进行加标回收试验,其回收率为95.00%～104.0%,相对标准偏差低于8.0%。盐水中高浓度的NaCl对碘含量的测定不产生明显的影响。该方法具有无毒、无害、污染小、操作简便等优点,可用于离子膜法烧碱工艺二次盐水和淡盐水中微量碘的测定。     

催化荧光光度法测定痕量镍（Ⅱ）

基于在pH 8.00缓冲溶液中,痕量镍对过氧化氢氧化靛蓝胭脂红的褪色起催化作用,建立了催化荧光光度法测定痕量镍的新方法。发射光谱在417 nm处,方法的线性范围为0.0～60 ng/mL,检出限为5.0×10-10g/L。用于自来水中镍的测定,回收率在98.3%～102.5%,实验结果满意。     

碳酸锂中硝酸根杂质的测定

本文研究了分光光度法测定碳酸锂中硝酸根杂质含量的方法。显色剂靛蓝二磺酸钠为氧化还原指示剂,还原态无色、氧化态呈蓝色,其氧化态可被强氧化剂进一步氧化为靛红及其衍生物,显色深浅与NO3-含量成线性关系。结果显示,NO3-含量在0.0～50μg范围内,符合朗伯―比耳定律,相关系数r为0.9994,精密度(RSD)小于2.25%,加标回收率在98.7%～101.2%之间,符合分析要求。     

甲基橙氧化褪色光度法测定微量碘的研究

基于硫酸介质中,碘酸根在溴化钾的催化作用下对甲基橙有较好的氧化褪色作用。建立了分光光度法测定微量碘的新方法.最大吸收波长为508 nm,表现摩尔吸光系数为3.13×104L/(mol.cm),线性范围为在0~50μg/(50 mL)。用于食品中碘的测定,获得满意结果。     

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.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。