石墨炉原子吸收光谱法快速测定血液中铅和镉

建立了石墨炉原子吸收光谱法快速测定血液中铅和镉的方法.使用5％ 硝酸溶液对样品进行脱蛋白处理,然后在旋涡混合器上振摇,离心后取上清液在石墨炉原子吸收光谱仪上进行测定.结果表明,Pb、Cd工作曲线线性关系良好,相关系数均大于0.9994;方法检出限分别为4.32μg/L和0.27μg/L;Pb的加标回收率为91.6％ ～...     

浊点萃取富集-石墨炉原子吸收光谱法同时测定环境水样和中药中超痕量铅和镉

提出了石墨炉原子吸收光谱法同时测定环境水样和中药中超痕量铅与镉的方法.以双硫腙为络合剂,在pH 7.0时,用Triton X-114非离子表面活性剂浊点萃取富集样品溶液中痕量铅和镉.用硝酸镁和磷酸二氢铵的混合液作为基体改进剂测定铅和镉,铅和镉的检出限(3s/k)分别为0.138,0.007μg·L-1,相对标准偏差(n=7)分别为1.90%,2.08%.对于10 mL样品溶液的富集倍数分别为18.3,17.7.应用所提出的方法测定了杨树叶(GBW 07604)和小麦粉(GBW08503)国家标准样品,测定结果与标准值相符.铅和镉的加标回收率分别为97.8%,94.0%(水样);98.0%,94.0%(中药样).     

火焰原子吸收光谱法测定高锑烟尘中的银、铅、镉

建立了火焰原子吸收光谱法测定高锑烟尘中的银、铅、镉的分析方法。试样经王水、高氯酸溶解后,利用四价锑的溴化物沸点较低的性质,将锑挥发除去,以消除基体锑对测定的干扰,在盐酸-高氯酸-硫脲介质中实现了银、铅、镉的连续测定。方法检出限:Ag为0.003 7μg/mL,Pb为0.019 8μg/mL,Cd为0.001 6μg/mL。相对标准偏差(RSD,n=11):Ag为0.92%~1.04%,Pb为1.29%~2.21%,Cd为1.99%~2.22%。加标回收率:Ag为99.30%~101.8%,Pb为98.60%~102.5%,Cd为98.40%~104.0%。方法准确、可靠、简便、快速,完全适用于高锑烟尘中银、铅、镉的测定。     

浊点萃取-石墨炉原子吸收光谱法同时测定生物样品中痕量铅和镉

提出了石墨炉原子吸收光谱法同时测定小鼠肝中痕量Pb和Cd的方法。以8-羟基喹啉为络合剂,在pH 9.0时,用Triton X-100浊点萃取富集样品中的Pb和Cd。用NH4H2PO4作为基体改进剂测定Pb和Cd,Pb和Cd的检出限(3s/k)分别为0.103μg/L和0.0136μg/L,相对标准差(n=6)分别为1.4%,0.73%。对于10 mL样品溶液的富集倍数分别为7.1,9.3。利用该法分别测定了小鼠肝中的Pb和Cd的含量,加标回收率分别为96.4%～97.1%和101.3%～103.2%。     

微波消解-石墨炉原子吸收光谱法测定污水厂污泥和进、出水中的镉、铅

建立了微波消解–石墨炉原子吸收光谱法测定污水处理厂进出水和污泥中重金属Cd,Pb的方法。分别向污水样品中加入5.0 mL硝酸,污泥样品中加入4.0 mL硝酸和2.0 mL双氧水,放入微波消解炉中进行消解。消解好的样品用1%NH_4H_2PO_4作为基体改进剂,在0.5%HNO_3介质中采用塞曼扣除背景,石墨炉程序升温方式进行Cd,Pb的原子化,用石墨炉原子吸收光谱法测定Cd,Pb的含量。Cd,Pb的质量浓度分别在0~2.00μg/L,0~40.0μg/L范围内与其吸收峰高呈良好的线性关系,线性相关系数分别为0.999 1,0.999 6。Cd,Pb检出限分别为0.104 9,0.394 5μg/L,测定结果的相对标准偏差分别为1.34%~3.61%,2.12%~2.80%(n=11),加标回收率分别为98.2%~102.6%,94.0%~100.4%。该方法简单,高效,结果准确度高,重现性好,适用于污水处理厂的进出水和污泥中重金属铅和镉的检测。     

布洛芬注射液包材相容性研究中铅、镉、砷、锑的测定

建立中性硼硅玻璃包材加速试验后布洛芬注射液中铅、镉、砷、锑含量的检测方法。采用微波消解仪以硝酸分解样品,用石墨炉原子吸收光谱仪测定铅、镉含量,测定波长铅为283.3 nm,镉为228.8 nm,铅、镉分别在5.0~50.0,0.5~5.0μg/L范围内有良好的线性,相关系数分别为0.999 7,0.996 2,检出限分别为0.26,0.01μg/L,测定结果的相对标准偏差分别为1.06%,2.40%(n=6),加标回收率分别为100.2%~101.9%,97.1%~105.1%。用原子荧光光谱仪测定砷、锑含量,测定波长砷为193.7 nm,锑为217.6 nm,砷、锑在1~10μg/L范围内均有良好的线性,相关系数分别为0.999 9,0.999 5,检出限分别为0.03,0.01μg/L,测定结果的相对标准偏差分别为1.04%,2.65%(n=6),加标回收率分别为94.2%~96.5%,92.6%~96.5%。该测定方法快速,灵敏度高,适用于内包装材料加速试验后药品中重金属元素含量变化的研究。     

流动注射双硫腙在线共沉淀预浓集石墨炉原子吸收光谱法测定人血中微量镉

本文用流动注射分析技术为石墨炉原子吸收光谱法测定人血中超微量金属元素建立了一个有效的在线共沉淀分离预浓集系统。基于痕量镉与双硫腙(DTZ)在弱酸性水溶液中共沉淀。沉淀收集在一编结反应器及一微型过滤器上,用60μL甲基异丁基酮(MIBK)溶洗沉淀,然后送入石墨炉进行测定。分析速度24样/h,样品消耗为1.4mL,获得的富集倍率为11。检出限(3σ)为0.003μg/L,浓度为0.06μg,/L镉时,测定精度为2.6%(n=7),测定人体血样标准参考物(GBW09132～GBW09134)中镉,结果与标准值一致。     

固相萃取-石墨炉原子吸收法测定海水中铅、镉和铜

采用C8固相萃取柱,建立了固相萃取-石墨炉原子吸收测定海水中Pb,Cd,Cu的方法,优化了固相萃取的吸附和解析条件。测定Pb,Cu线性范围为0~100μg/L,Cd线性范围为0~4μg/L,相关系数(r)不低于0.9993。Pb,Cd,Cu检出限(3σ,n=11)分别为0.66,0.023和0.48μg/L;标准偏差分别为4.0%,0.84%和4.4%;加标回收率分别为102%,96%和97.3%。方法能有效克服海水中复杂基体干扰问题,已用于海水样品中痕量Pb,Cd,Cu的测定。     

微波消解-石墨炉原子吸收法快速检测葡萄酒中铅、镉

葡萄酒样品采用电热消解仪140 ℃预消解30 min后,经过微波消解仪处理,消解条件为:V(HNO3)∶V(H2O2)＝7∶1,180 ℃,800 W,10 min,然后采用石墨炉原子吸收法对其中铅、镉含量进行测定.研究表明,将本法应用于葡萄酒样品中Pb、Cd的测定,结果令人满意,Pb和Cd的检测限分别为3.0 μg/L和0.5 μg/L,RSD均小于5.0%,回收率Pb 74.5%～101.5%,77.3%～104.3%.     

微波消解-石墨炉原子吸收光谱法测定鱼肉和河蚌中的重金属

建立微波消解样品,石墨炉原子吸收光谱法测定鱼肉和河蚌中重金属Pb,Cd,Cr,Cu,Ni含量的方法。优化了石墨炉原子吸收光谱法测定条件,在最佳实验条件下,选用磷酸二氢铵作为Pb,Cd,Cr,Cu的基体改进剂,抗坏血酸作为Ni的基体改进剂。Pb,Cd,Cr,Cu,Ni的检出限分别为0.05,0.01,0.05,0.05,0.07μg/g,实际样品测定结果的相对标准偏差为6.3%~14.5%(n=6),加标回收率为84.5%~113.0%。测定了牡蛎标准参考样,测定值在标准值可接受范围内。该方法检出限低、准确度高,适用于鱼类、河蚌样品中重金属含量的分析。     

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.