流动注射法同时测定海水中氨氮和磷酸盐

采用流动注射法同时测定海水中氨氮和磷酸盐的含量。在优化的试验条件下,氨氮和磷酸盐的线性范围分别为0.25 mg·L-1和0.30 mg·L-1以内,检出限(3S/N)分别为0.42μg·L-1和0.56μg·L-1。氨氮和磷酸盐加标回收率分别在85.0%~103%和86.7%~103%之间,测定值的相对标准偏差(n=6)分别在0.43%~5.3%和0~4.1%之间。方法用于分析标准物质,测定结果与分光光度法的结果一致。     

电感耦合等离子体原子发射光谱法测定大气颗粒物中的12种重金属元素含量

采用电感耦合等离子体原子发射光谱法测定大气颗粒物中12种重金属元素的含量。用石英滤膜收集大气颗粒物中的12种重金属元素,分别采用电热板和微波消解法处理样膜。电热板消解时,12种重金属元素的检出限在0.001~0.07 mg·L~(-1)之间,测定下限在0.004~0.28mg·L~(-1)之间,测定值的相对标准偏差(n=6)在0.78%~5.8%之间。微波消解时,12种重金属元素的检出限在0.001~0.05mg·L~(-1)之间,测定下限在0.004~0.20mg·L~(-1)之间,测定值的相对标准偏差(n=6)在0.46%~4.5%之间。应用该方法分析了标准样品,所得测定值与认定值相符。     

气相色谱-质谱法测定酒中16种邻苯二甲酸酯

应用气相色谱-质谱法测定酒中16种邻苯二甲酸酯的含量。样品经乙酸乙酯提取,所得提取液用DB-5MS UI色谱柱分离,在全扫描/选择离子监测共用模式下测定。16种邻苯二甲酸酯的质量浓度均在0.5~10.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.01~0.10mg·L-1之间。日间加标回收率在83.7%~114%之间,日间相对标准偏差(n=6)在3.4%~9.8%之间;日内加标回收率在81.9%~113%之间,日内相对标准偏差(n=6)在1.5%~6.7%之间。     

改进的重铬酸盐法测定水和废水中化学需氧量

对重铬酸盐法测定水和废水中化学需氧量的国家标准方法作了改进。改进方法较原方法的取样量由20.00mL减少为10.00mL,氯离子掩蔽剂硫酸汞由固体改为溶液;改进方法受氯离子干扰的程度与国标方法相似,当氯离子质量浓度小于1 000mg·L-1时对测定结果无影响。改进方法的检出限为3 mg·L-1,对标准物质和标准溶液进行测定,测定结果的相对误差在0.96%~2.70%之间,标准偏差在0.80~5.6 mg·L-1之间,相对标准偏差(n=6)在0.80%~5.9%之间。方法应用于水样的测定,测定值与国标法测定值相符,测定值的标准偏差在0.94~20.5mg·L-1之间,相对标准偏差(n=6)在0.53%~11%之间。     

超高效液相色谱法测定羊栖菜中岩藻甾醇的含量

采用超高效液相色谱法测定羊栖菜中岩藻甾醇的含量。羊栖菜试样(2.000 0g)经甲醇-二氯甲烷(1+1)混合液提取,所得提取液以YMC-Pack ODS-A色谱柱为分离柱,以甲醇-乙腈(3+7)混合液为流动相,在检测波长210nm处进行测定。岩藻甾醇的质量浓度在0.5~400mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.16mg·L~(-1)。在25,50,100mg·L~(-1)等3个浓度水平进行加标回收试验,回收率在91.2%~96.8%之间。测定值的日内及日间相对标准偏差(n=6)分别在1.1%~5.4%,2.8%~7.0%之间。     

同位素稀释-气相色谱-质谱法测定白酒中23种邻苯二甲酸酯类化合物

提出了同位素稀释-气相色谱-质谱法测定白酒中23种邻苯二甲酸酯类化合物含量的方法。样品用正己烷-乙酸乙酯(1+1)混合液提取后,经DB-5MS毛细管色谱柱分离,采用电子轰击离子源选择离子反应监测模式进行质谱测定,同位素内标法进行定量分析。23种邻苯二甲酸酯类化合物的线性范围在0.2~3.0mg·L-1之间,测定下限(10S/N)在0.05~0.1mg·kg-1之间。加标回收率在73.2%~122%之间,相对标准偏差(n=6)在0.49%~11%之间。     

气相色谱法测定食品中仲丁灵残留量

提出了气相色谱法测定食品中仲丁灵残留量的方法。样品用正己烷-丙酮(1+1)混合液提取,提取液经凝胶渗透色谱和固相萃取净化。用DB-1701色谱柱分离,电子捕获检测器测定。仲丁灵的质量浓度在10.0~500μg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)为1.4μg·kg-1。添加10,20,50μg·kg-1 3个浓度水平进行加标回收试验,回收率在84.2%~97.2%之间,测定值的相对标准偏差(n=8)在3.8%~15%之间。     

气相色谱-硫化学发光检测器法测定车用汽油中6种硫醚

采用气相色谱测定车用汽油中6种硫醚的含量。用DB-1毛细管色谱柱(60 m×0.32mm,0.50μm)分离和硫化学发光检测器检测。6种硫醚的质量浓度均在0.5~150mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.03~0.26mg·kg-1之间。方法用于车用汽油的分析,加标回收率在76.6%~120%之间,测定值的相对标准偏差(n=7)在0.50%~6.4%之间。     

顶空-气相色谱-质谱法测定地表水和废水中55种挥发性有机物含量

采用顶空-气相色谱-质谱法测定地表水和废水中55种挥发性有机物的含量。选择顶空平衡温度和时间分别为65℃和50min。在气相色谱分离中用DB-624色谱柱为固定相,在质谱分析中采用全扫描和选择离子监测模式。以氟苯和1,2-二氯苯-D4为内标物。55种挥发性有机物的线性范围均为10.0~400μg·L-1。全扫描模式下,检出限在0.8~6.8μg·L-1之间,加标回收率在81.3%~116%之间,测定值的相对标准偏差(n=6)在0.40%~15%之间。在选择离子监测模式下,检出限在0.2~1.1μg·L-1之间,加标回收率在81.0%~117%之间,测定值的相对标准偏差(n=6)在0.40%~6.5%之间。     

甲基紫探针吸收光谱法测定阿魏酸钠

在pH 4.2的乙酸-乙酸钠缓冲溶液中,甲基紫与阿魏酸反应生成具有负吸收峰的紫色络合物。其最大负吸收波长位于565nm,阿魏酸的质量浓度在0.1~3.9mg·L-1范围内与吸光度呈线性关系,服从比耳定律,表观摩尔吸光率(ε)为4.36×104L·mol-1·cm-1。方法用于市售药物中阿魏酸钠含量的测定,回收率在99.5%~103%之间,测定值的相对标准偏差(n=6)在1.3%~1.5%之间。     

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.