ICP-AES法测定钢中的铈

建立了离子体发射光谱仪测定钢中铈元素的方法。为消除共存元素对铈分析游线的光谱干扰,选择Ce413．380nm作为分析线,铈含量在0．005％-0．50％之间工作曲线线性良好。对于含量范围在0．005％-0．10％的铈元素,回收率为85．6％-12．5％,测定结果的相对标准偏差小于9．74％（n=8）;对于含量范围在0．10％-0．50％的铈元素,回收率为99．5％-103．0％,测定结果的相对标准偏差小于3．52％（n=8）。该方法适宜钢中含量范围在O．005％-0．50％的铈元素的测定。     

离子色谱法测定水中总氮

用离子色谱法检测水中总氮,检测波长为205nm,整个分析过程仅需7min。方法的检出限为0．03mg／L．测定结果的相对标准偏差为2．1％～3．5％(n=7),加标回收率为99．0％～103．5％。用离子色谱法和分光光度法对水样进行测定,两种方法测定结果的相对偏差不大于2．1％。     

微波消解平台石墨炉原子吸收法测定活性污泥中的铜和铅

建立了一种微波消解样品,平台石墨炉原子吸收法测定活性污泥中Cu、Pb含量的方法,该方法的样品加标回收率Cu为95．6％～98．3％,Pb为92．3％～97．0％,相对标准偏差RSD（%）：Cu为1．0％～2．0％,Pb为2．0％～2．9％,检验限Cu为0．0052ng／g,Pb为0．0073ng／g,该方法应用于活性污泥中Cu,Pb的分析,实验所需时间短,取样量少,空白值低,实验过程中样品损失少,准确度和灵敏度高,结果令人满意．     

火焰原子吸收光谱法测定貉被毛中铜、锌含量的研究

摘要：为建立测定被毛中铜、锌含量的方法,采用火焰原子吸收光谱法测定了貉被毛中铜、锌含量。结果表明,该法测定铜、锌的加标回收率为97．78％和97．32％,相对标准偏差为1．19％和2．46％。方法可行。     

橡胶材料的X射线荧光多元素分析

建立了一种橡胶材料中多元素X射线荧光定量分析的方法。用标准物质对此方法进行检验,相对标准偏差为0．30％－0．58％。该方法用于橡胶样品的测定,相对标准偏差为0．33％－0．62％。     

染毒粮食中7种化学战剂的气相色谱分析方法

为了研究染毒粮食（大米、面粉）中７种化学战剂的检测方法,建立了相应的气相色谱分析方法。该法采用火焰光度检测器检测,ＢＰ－１０毛细管色谱柱分离,二氯甲烷萃取。模拟染毒大米、面粉中化学战剂测定相对误差为２．０％～１２．０％、８．１０％～２７．３％。相对标准偏差分别为０．９％～６．１０％、３．９５％～１６．８％。方法的最低检出浓度为０．０１～２μｇ／ｇ。所建方法操作简便,灵敏度高。     

微波消解-火焰原子吸收法测定土壤中的钴

建立了微波消解一火焰原子吸收法测定土壤中钴的方法：用微波消解土壤、电热板加热驱酸的方法对土壤样品进行前处理,优化了微波消解条件。方法的加标回收率为93．0％～106．0％,检出限为3．0μg/g,测定结果的相对标准偏差为2．1％～4．9％（n=6）。     

反相高效液相色谱法同时测定保健口服液中20种甾体激素的研究

建立了利用反相高效液相色谱法同时测定保健口服液中２０种甾体激素的方法,进行了色谱条件的优化和样品预处理方法的探讨,并应用于市售保健口服液中微量激素的测定。最低检出量为０．１６～３．１８ｎｇ,回收率为８０．５％～１０３．１％,相对标准偏差为３．４％～９．２％。     

高效毛细管电泳法测定罂粟壳中生物碱的含量

采用高效毛细管电泳法测定罂粟壳中可待因、吗啡和罂粟碱的含量,结果表明可待因的加样回收率为９６．６１％,吗啡为９５．９０％,罂粟碱为９５．３７％。方法简便、准确、重现性好,可作为生物碱的质量控制方法。     

高效液相色谱法与酶联免疫试剂盒测定海水中痕量氯霉素

详细报道了海水样品中氯霉素的高效液相色谱检测方法及酶联免疫试剂盒检测方法。应用高效液相色谱法测定海水中氯霉素，方法的线性范围为5～50ng，检出限为0．064ng，回收率为96．2％-118．4％，相对标准偏差小于8．9％。酶联免疫试剂盒测定海水中的氯霉素背景值偏高，在加标浓度为10ng／mL时回收率为101．0％，相对标准偏差为8．32％。     

Effect of cationic monomer on properties of fluorinated acrylate latex

Cationic fluorinated acrylate latex was prepared via semi-continuous emulsion copolymerization of cationic monomer and other monomers.The resultant latex and its film were characterized with dynamic light scattering detector and contact anglc meter. Influences of amount of DMDAAC on the propcrtics of resultant latex and its film were investigated in detail.Results show that the particle size of the latex has the minimum value and the zeta potential of the latex is increased when the amount of DMDAAC is increased.In addition,the particle size of the latex is unimodal distribution when the amount of DMDAAC is not more than 2.5%. However,the particle size of the latex is bimodal distribution when the amount of DMDAAC is more than 2.5%.The contact angle is varied slightly with the increase of amount of DMDAAC when it is not more than 2.5%.Nevertheless,the contact angle is decreased with the increase of the amount of DMDAAC when it is more than 2.5%.     

毛细管电泳叠加对比法测定阿片粉中吗啡的含量

 用毛细管区带电泳 ,以叠加对比法对阿片粉中的吗啡进行了定量分析 ,样品的回收率为 10 0 .6 % ,峰迁移时间的相对标准偏差 (RSD)不大于 2 .4 % ,相对迁移时间的RSD不大于 1.1% ,相对峰面积的RSD不大于 0 .5 1%。与内标对比工作曲线法作了比较 ,实验表明两种分析方法的结果无显著性差异 ,叠加对比法具有简便、快速、准确的优点 ,可用于样品中有效成分的快速定量。     

长链烷基冠醚在烯烃环氧化反应中的相转移催化作用

为了实现温和条件下烯烃的环氧化,近年来模拟细胞色素P-450单加氧酶催化烃类氧化的研究十分活跃,其中以金属卟啉/NaOCl(CH_2Cl_2/H_2O)模拟体系研究最多.从近年文献看,在Meunier等建立的该两相催化反应体系中,通过改变催化剂的结构、各种助剂及氧源浓度等可达到较好的催化效果,其相转移剂一般选用季铵盐类化合物.有文献报导以聚乙二醇取代季铵盐,结果证明聚乙二醇的相转移作用也很明显.本文将一类新型的非离子型表     

Synthesis of 1,4,5,6,7,7-hexachloro- and hexabromobicyclo-[2,2,1]-5-heptene-2-carboxylic acid vinyl esters and copolymerization with acrylonitrile

1,4,5,6,7,7-Hexachloro- and hexabromobicyclo-[2,2,1]-5-heptene-2-carboxylic acid vinyl esters have been prepared by esterification of the Diels-Alder addition products of hexachloro- and hexabromocyclopentadiene with acrylic acid. These monomers have been copolymerized with acrylonitrile to yield flame-retardant polymers. Copolymers having a chlorine content up to 18.35% or a bromine content up to 6.35% burn, but copolymers containing 25.0% or more of chlorine or 9.83% or more of bromine do not support combustion.     

Towards the automatic analysis of NMR spectra: part 6. Confirmation of chemical structure employing both 1H and 13C NMR spectra

A method of comparing predicted and experimental chemical shifts was used to confirm or refute postulated structures. 1H NMR spectra returned all true positives with a false positive rate of 4%. When an analogous procedure was adopted for 13C NMR spectra, the false positive rate dropped to 1%, whereas the more practical HSQC data yielded a false positive rate of 2%. If the HSQC results were combined with 1H results, a false positive rate of 1% resulted, 4 times more accurate than 1H alone.     

Fluorination of aromatic compounds with F2 and acetyl hypofluorite: synthesis of 18F-aryl fluorides by cleavage of aryl-tin bonds [1]

Elemental fluorine and acetyl hypofluorite, labeled with ¹⁸F, were added to eight simple aryl-tin derivatives. Both reagents gave good radiochemical yields of labeled aryl fluorides. Overall, acetyl hypofluorite gave more consistent yields (～70%), while F₂ gave more variable yields (54% – 95%).     

Rheological, mechanical and transport properties of blown films of high density polyethylene nanocomposites

In this work, high density polyethylene (HDPE) was mixed in a twin screw extruder with organophilic treated clay, Cloisite 20A, and a compatibility agent, a HDPE grafted with maleic anhydride (PEMA). The screw profile was changed from a less dispersive (Profile 1) to a high dispersive configuration (Profile 2). A masterbatch procedure was used to obtain a final organoclay concentration of 5 wt.%. Both profiles allowed the intercalation of the HDPE into the clay, increasing the clay’s gallery distance to 3.7 nm. However, the samples produced with Profile 2 (Nano 2 samples) were more elastic and had a more stable structure than the samples produced with Profile 1. Therefore, two kind of blown films of Nano 2 samples were made: FN1 and FN2. The last one was blown at a higher screw velocity than the FN1. Both films had an increase of 95% in the elastic modulus and a reduction of 60% and 45% in O₂ and water vapor permeability rates, respectively, compared to the film of pure HDPE. However, the FN2 structure was more unstable than the FN1 structure. It was concluded that both screw profiles gave the same level of HDPE intercalation in the clay; however, the more dispersive profile produced more time-stable and elastic structures. The increase in the elongation rate during the film blowing process produced also more time-stable morphologies; however, this higher orientation created matrix/filler interfacial defects.     

一种用于快速成型工艺的红光光敏树脂的性能研究

合成了一种吸收波长为 6 80nm的菁染料 有机硼盐复合物光引发剂CDBC ,以 6 80nm激光二极管发射的激光作为光源 ,研究了由CDBC、EA6 12、POTMPTA组成的红光光敏树脂在快速成型工艺中的应用 ,考察了影响树脂几个主要性能即粘度、光固化速度、体积收缩率的因素 .结果表明 ,EA6 12含量高 ,POTMPTA含量低 ,树脂粘度大 ,体积收缩率小 ;相反 ,EA6 12含量低 ,POTMPTA含量高 ,则树脂粘度低 ,体积收缩率大 ;光引发剂CDBC含量 5 %以内时对树脂粘度和体积收缩率没有影响 ,CDBC含量增加 ,树脂的表固速度加快 ,但当CDBC含量大于 3%时 ,表固速度基本不变 .预聚物EA6 12质量分数 70 % ,单体POTMPTA质量分数 2 7% ,光引发剂CDBC质量分数 3%时 ,树脂粘度为 4 2 0mPa·s ,表固时间为 1 0s ,固化体积收缩率为 4 0 % ,具有较好的综合性能 .     

Pesticide residues on fruits and vegetables from Ontario, Canada, 1991-1995

For the 5-year period 1991 to 1995, 1536 vegetable and 802 fruit samples were analyzed. The purpose of this study was to determine if pesticides were present on Ontario-produced fruits and vegetables, and if so, to determine if residues violated maximum residue limits (MRLs). Overall, 31.5% of the samples had no detectable pesticide residues, whereas 68.5% contained one or more residues. Most of the residues were present at very low concentrations; 48% of the detections were < 0.1 parts per million (ppm), and 86% were < 1 ppm. However, violations of MRL were observed in only 3.2% of the vegetables samples and 3.1% of the fruit samples. In addition, 4.8% of the samples contained a "technical" violation, that is, there was no specified MRL for the pesticide-commodity combination and the residues exceeded 0.1 ppm. Of the detectable residues, 63% were < 10% of the MRL, whereas 89% were < 50% of the MRL. More fruit samples (91.4%) had a detectable residue, compared with vegetable samples (56.6%). Fruit is often treated close to harvest or post harvest to ensure that wholesome produce reaches the consumer. Forty-six percent of the samples contained 2 or more residues, and 2% of all samples had more than 5 different pesticides detected; fruit samples tended to have more multiple residues. The most frequently found pesticides were captan, the dithiocarbamate fungicides, endosulfan, azinphos-methyl, phosmet, parathion, and iprodione. These pesticides were also used in the greatest quantity for crop production. Overall, the data agree fairly closely with those reported for the U.S. Department of Agriculture Pesticide Data Program because the 2 programs have similar analytical goals and objectives.     

Spectroscopically distinct sites present in methyltrioxorhenium grafted onto silica-alumina, and their abilities to initiate olefin metathesis

Deposition of CH3ReO3 onto the surface of dehydrated, amorphous silica-alumina generates a highly active, supported catalyst for the metathesis of olefins. However, silica-alumina with a high (10 wt %) Re loading is no more active than silica-alumina with low (1 wt %) loading, while CH3ReO3 on silica is completely inactive. Catalysts prepared by grafting CH3ReO3 on silica-alumina contain two types of spectroscopically distinct sites. The more strongly bound sites are responsible for olefin metathesis activity and are formed preferentially at low Re loadings (< or =1 wt %). They are created by two Lewis acid/base interactions: (1) the coordination of an oxo ligand to an Al center of the support and (2) interaction of one of the adjacent bridging oxygens (AlOSi) with the Re center. At higher Re loadings (1-10 wt %), CH3ReO3 also interacts with surface silanols by H-bonding. This gives rise to highly mobile sites, most of which can be observed by 13C solid-state NMR even without magic-angle spinning. Their formation can be prevented by capping the surface hydroxyl groups with hexamethyldisilazane prior to grafting CH3ReO3, resulting in a metathesis catalyst that is more selective, more robust, and more efficient in terms of Re use.