微分电位溶出法连续测定饮料中的铜铅镉锌

建立了微分电位溶出法连续测定饮料中痕量铜、铅、镉、锌的新方法。在HAc- Na Ac( p H4 .5)～ 3.5× 1 0 -2 mol·L-1KCl～ 2 .6× 1 0 -5 mol· L-1Hg2 +介质中测定锌 ,然后调节底液为 0 .0 1 mol·L-1HCl,连续测定铜、铅、镉。铜、铅、镉、锌 ,检出限分别为 4 ,0 .1 ,2 ,4 μg· L-1,线性测定范围 Zn2 +:0～ 30 0 μg·L-1,Cu2 +、Pb2 +、Cd2 +:0～ 2 2 0μg· L-1,回收率为 83.4 %～ 1 0 3.3% ,RSD<3.4 % ( n=7)。该法较好解决了金属互化物的影响 ,样品不需消化便可直接测定。     

微波消化-在线固相萃取富集高效液相色谱法测定饲料用灌木中痕量铅镉汞

研究了用微波消化样品,WatersXterraTMRP18(3.9mm×20mm)色谱柱在线固相萃取富集,二极管矩阵检测器检测,高效液相色谱测定饲料用灌木中痕量铅、镉、汞的方法。铅、镉和汞含量在0.1～100μg·L-1范围内与峰面积呈线性关系,方法检出限(S/N=3)为:铅2.0ng·L-1,镉1.5ng·L-1和汞2.0ng·L-1,方法相对标准偏差为2.0%～3.1%,标准回收率为94%～103%,该方法用于测定饲料用灌木中低含量的铅、镉、汞,结果满意。     

氢化物发生HG-ICP-AES测定动物源性水产品中的无机砷含量

建立了氢化物发生电感耦合等离子发射光谱(HG-ICP-AES)测定动物源性水产品中无机砷含量的方法,并对ICP-AES工作参数及氢化物发生条件进行了优化和选择.方法的检出限为0.92 μg·L-1,线性范围为0～100 μg·L-1,相对标准偏差为1.24%;回收率范围为98.5%～101.6%.本法适用于低含量无机砷含量的日常检测测定.     

氢化物原子荧光光谱法测定食品中铅

研究了500 ℃干灰化法氢化物原子荧光光谱法测定食品中微量铅,在 15 g·L-1硼氢化钾还原剂介质和5 g·L-1氢氧化钾溶液中,样品溶液酸度以 0.24 mol·L-1盐酸为最佳。铅浓度在5~30μg·L-1范围内呈线性,相关系数为0.993 7。RSD小于10%,回收率为91%~104%。     

氢化物发生-原子吸收光谱法测定蔬菜中痕量铅

采用微波消化、氢化物发生-原子吸收光谱法测定蔬菜中痕量铅。研究了硼氢化钾用量、酸介质及其酸度对铅的测定影响,采用铁氰化钾-草酸体系可消除金属元素对铅测定的干扰。检出限为0．023μg·L-1,回收率为97．8％～105．6％,RSD为0．8％～1．8％,线性范围为0～40μg·L-1。     

区域地球化学样品中磷、钒、铬、镍、硒等13元素的高效测定方法研究

本文采用硝酸、氢氟酸、高氯酸等三种混合酸预消解,再用王水、盐酸分两次复溶提取,电感耦合等离子体质谱仪（ICP-MS）测定钴、铜、钼、铅、镉,电感耦合等离子体发射光谱仪（ICP-OES）测定磷、钒、铬、锌、钾、镍、锰,原子荧光发射光谱仪（AFS）测定硒,最终实现区域地球化学样品中磷、钒、铬等13元素的准确、高效、组合测定。在选定的实验条件下,各元素的检出限分别为：磷8.42μg·g-1、钒2.55μg·g-1、铬2.00μg·g-1、镍0.50μg·g-1、锌2.00μg·g-1、氧化钾0.05μg·g-1、锰8.00μg·g-1、钴0.20μg·g-1、铜0.80μg·g-1、钼0.10μg·g-1、镉0.01μg·g-1、铅1.70μg·g-1、硒0.01μg·g-1;准确度分别为：砷0.000~0.011、钒0.001~0.002、铬0.001~0.002、镍0.002~0.012、锌-0.008~0.009、氧化钾-0.001~0.005、锰0.003~0.006、钴0.005~0.008、铜0.001~0.006、钼-0.003~0.002、镉0.002~0.020、铅0.003~0.007、硒-0.007~0.008;精密度分别为：磷1.11%~2.95%、钒1.91%~2.52%、铬1.02%~3.41%、镍1.89%~5.56%、锌1.37%~3.05%、氧化钾1.99%~3.47%、锰0.51%~1.98%、钴3.01%~3.28%、铜2.31%~2.77%、钼2.01%~7.20%、镉5.81%~7.76%、铅2.01%~3.65%、硒3.98~7.43%;均满足或优于《多目标区域地球化学调查规范（1：250000）》要求,该方法具有操作简单、多元素同时测定、方法检出限低、测定线性范围宽、准确度高、精密度好等优点,尤其是协同高效,大大节约水、电、试剂等特点,适合实验室广泛推广应用。     

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痕量铂和钯

以聚氨酯泡沫塑料为吸附剂于静态操作条件下,对痕量铂和钯的选择性吸附分离的方法进行了研究。试验表明,泡塑在3.6～4.8mol·L-1HCl溶液与40g·L-1SnCl2溶液构成的吸附介质中,对铂、钯的吸附性能很好,饱和吸附容量为12.90～19.24mg·g-1,钯平均吸附率为95.81%,铂平均吸附率为98.35%,吸附到泡塑中的铂、钯可用灰化法回收,富集倍数可达100倍。结合电感耦合等离子体质谱法,可用于地质样品中痕量铂、钯的富集分离和测定。方法经标准样品分析验证,铂、钯的测定结果与推荐值吻合,标样及样品分析的RSD≤6.5%(n=12)。     

高效液相色谱-电感耦合等离子体质谱法测定饮用水中碘酸根和碘离子

提出了高效液相色谱-电感耦合等离子体质谱法测定饮用水中碘酸根和碘离子的方法。饮用水样品通过Dionex IonPac AS14阴离子交换柱及AG14保护柱分离碘酸根和碘离子,用50mmol.L-1碳酸铵溶液(用氨水调至pH 9.9)作流动相进行淋洗。于洗脱液中用电感耦合等离子体质谱法分别测定碘酸根和碘离子的含量,两者的线性范围均为0.20～300μg.L-1,检出限(3S/N)依次为0.09μg.L-1和0.13μg.L-1。以饮用水为基体加入两个不同浓度水平的标准溶液按方法分析后,求得方法的回收率及精密度为①碘酸根回收率在100.5%～113.0%,相对标准偏差(n=8)在1.2%～2.8%之间;②碘离子回收率在101.9%～110.7%,相对标准偏差(n=8)在1.3%～2.0%之间。     

高效液相色谱-电感耦合等离子体质谱法测定烟草及其制品中3种铅形态

建立了高效液相色谱-电感耦合等离子体质谱法(HPLC-ICP-MS)测定烟草及其制品中无机铅[Pb(Ⅱ)]、三甲基铅(TML)和三乙基铅(TEL)含量的方法.将烟草样品粉碎后,加入体积比为60∶40的1 mmol·L-1 1-戊烷磺酸钠溶液和甲醇的混合溶液(流动相)15 mL,于40℃超声萃取20 min,离心,上清液...     

离子色谱法测定微量碘的检测器应用研究

以NaOH为淋洗液 ,分别使用电导、直流安培和紫外检测器优化了碘的离子色谱分离和测定条件 ,检出限分别为 30 ,1和 2 5 μg·L- 1。选用安培检测法测定了奶粉中低于 10 0 μg·L- 1的微量碘 ,回收率达到 89.0 %     

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.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.