化学发光法测定饮用水中痕量Al(Ⅲ)

<正>铝广泛存在于食品、水和医药品中。该元素是导致多种疾病的重要因素。过多的铝逐渐沉积在人的大脑和骨骼中,导致铝性脑病及骨病[1],当大脑中铝含量大于4mg/g(脑干重)即可引起神经纤维变性[2]。我国生活饮用水卫生标准中规定了水中铝的含量不能超过0.2mg/L[3]。     

空气-乙炔火焰原子吸收法测定锌合金中铝

在原子吸收分光光度法中,由于铝易形成难离解的氧化物,灵敏度非常低,一般不能使用空气-乙炔火焰法,而是采用能提供较高原子化温度的一氧化二氮-乙炔火焰法或石墨炉法进行铝的测定.但在操作一氧化二氮-乙炔火焰时较危险,以及用石墨炉法测含铝大于0.x%的样品时,对试液要进行高倍数的稀释,操作比较费时,文献[3]对空气-乙炔火焰原子吸收法测铝进行了初步探讨.文献[4]报道了以含氮化合物作为增敏剂对铝的测定.本文采用空气-乙炔火焰原子吸收法和CTMAB作增敏剂进行铝的测定研究.可使铝的灵敏度提高5～6倍,检出限为10μg·ml~(-1).实现了空气-乙炔火焰法测定锌合金中铝,结果满意.1 试验部分1.1 仪器与试剂PF2380型原子吸收分光光度计     

石墨炉原子吸收光谱法测定复合疏松剂中铝

提出了石墨炉原子吸收光谱法测定复合疏松剂中铝含量的方法.制备了涂钽石墨管以消除铝在石墨管中的记忆效应,采用硝酸镁和硝酸钯的混合溶液作为基体改进剂,灰化温度从700℃升至1 300℃.对升温程序作了详细的叙述.铝的质量浓度在80μg·L-1范围内与其吸光度呈线性关系,检出限(3σ)为0.02μg·L-1.应用此法分析了普通泡打粉和无铝泡打粉中的铝含量,加标回收率分别为91%,95%,相对标准偏差(n=6)分别为8.3%,7.9%.     

低氧低分压环境下聚氨酯泡沫塑料富集-电感耦合等离子体质谱法测定地质样品中微量金

金具有良好的稳定性,不容易迁移富集,在岩石矿物中含量较低。微量金的分析方法主要有化学光谱法[1-2]、石墨炉原子吸收光谱法[3-4]、分光光度法[5-6]和电感耦合等离子体质谱法[7-8]等。化学光谱法和分光光度法存在流程长、工作强度大等缺点;石墨炉原子吸收光谱法稳定性差、线性范围窄,不适合     

石墨炉原子吸收光谱法测定食品中的铝含量

建立了食品中铝含量的石墨炉原子吸收光谱方法。样品经消化后,在396.2 nm分析波长下,不加基体改进剂,直接用石墨炉原子吸收光谱法测定食品中的铝。线性范围为0～200μg/L,相关系数r=0.9986,测定结果的相对标准偏差(RSD)小于4%。用该方法对有证标准物质进行测定,测定结果与标准值相符合。该法能满足各类食品中铝含量检测的要求。     

铝氟联合中毒大鼠骨、脑、血、尿中多元素含量动态检测

同批断乳两周的Wistar雄性大鼠59只,随机分为3个组,用同一病家的高岭土拌煤烘干与柴烘玉米加入配合饲料喂养.饲料含氟、铝3.9×10-6,12.4×10-6;107×10-6,40.4×10-6;212,66.8×10-6.实验11、20周分两批股动脉放血处死.检测了大鼠骨、脑、血、尿中多种元素.结果表明,血清钙一直较高,磷降低.实验11周,Ⅱ、Ⅲ组骨氟分别增高6、10倍,尿氟增高4、6倍;骨、脑、全血铝均随摄氟、铝量的增多而递减,尿铝递增.尿中其它元素多一直减少.骨中金属元素随骨铝的递减而递减.Ⅱ组全血锌显著下降.实验20周,Ⅱ、Ⅲ组骨氟是Ⅰ组的3.5和8.2倍,为实验11周时的58.1%和80.7%;尿氟是1.4和3倍.骨、脑铝随氟、铝摄入量的递增而递增,骨中金属元素含量也随之递增,骨磷降低.全血磷递增,锌均升高.本实验多元素含量由低向高变化的逆反过程与骨软化向硬化的病理转换相吻合;铝和氟彼此可影响对方的体内过程和在骨骼中的蓄积并引起多元素含量和相关性的显著变化.提示消化道内源性无机盐排泄过多;低龄动物的骨、脑对铝有排斥反应,但有铝危害表现.     

用左旋多巴-示差脉冲伏安法间接测定生物样品中的铝

人体内摄入过多的铝可能导致或促进阿尔茨海默氏病 ( Alzheimer s disease)、帕金森氏病( Parkinson s disease)及透析脑病 ( Dialysis encephalopathy)的发病 [1] .原子吸收光谱法、能量分布 X射线光谱法、 X射线微探针分析法、激光微探针质量分析法和核显微法曾用于测定脑铝 .这些方法在样品制作过程中易被污染 [2 ,3] ,仪器昂贵 ,灵敏度不高 ,而且均不能用于人体液和脑铝的在体检测 .由于铝的还原电位约 - 1 .7V,易受 H+干扰 ,直接测定铝有困难 .吸附伏安法利用铝与染料的配合物的电化学响应来测定环境和生物制品中的铝 ,检测下限达 1…     

原子吸收光谱法测定催化剂中高含量镍

加氢催化剂在我国炼油工业中一直起着十分重要的作用。其主要成分有硅、铝、钼、镍、磷等元素 ,这些金属元素在催化剂中大多以金属氧化物形式存在 ,该催化剂过去通常用硫酸溶解试样 ,光度法分析其中金属元素含量。但使用该溶样方法 ,无法进行原子吸收光谱法测定。本法在聚四氟乙烯压力溶弹内 ,用王水作溶剂溶解样品 ,具有试剂用量少 ,免受污染等优点。目前应用较为广泛的测定镍的方法有分光光度法[1] 、石墨炉原子吸收光谱法[2 ] 、电感耦合等离子体发射光谱法[3] 。分光光度法需较长时间 ,操作复杂 ,所用试剂比较多 ;石墨炉原子吸收光谱法…     

影响面粉中铝含量测定因素分析

目的探讨了江苏省疾控[2009]97号文件附录A《面制品及海蜇中铝的测定方法》测定面制食品中铝含量。方法样品经干法消化后,在乙二胺-盐酸缓冲溶液中,三价铝在十六烷基三甲基溴化铵阳离子表面活性剂存在下,与铬天青S形成绿色三元体系,其吸光度与铝的含量在一定含量范围内成正比。结果样品消化液在定容30 min时测定结果接近中位值,方法线性系数r=0.999 7,相对标准偏差在3.3%~3.7%之间,样品回收率在88.9%~96.4%。结论该法操作简便,灵敏度高,适用于各实验室开展检测。     

石墨炉原子吸收光谱法测定人尿和血以及发中铝

铝在临床医学领域内日益引起人们的兴趣和关注,在职业性危害中吸入铝的粉尘和烟能引起“铝尘肺”;测定铝的方法过去采用比色法,费工耗时,火焰原子吸收光谱法灵敏度不够,采用石墨炉原子吸收光谱法测定,大大提高了灵敏度,而且需样量少,可作为一种在临床上有较高应用价值的诊断手段。 将制备好的样品,注入石墨炉原子化器中,原子化后,待测元素的基态原子吸收来自同种元素,空心阴极灯发出的特征潜线(Al 309.3nm),Al在一定范围内,吸光度与其含量成正比,与标准系列比较进行定量。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.