气相色谱-质谱法选择离子存储检测模式测定皮革和纺织品中富马酸二甲酯

提出了用气相色谱-质谱法选择离子存储检测模式测定皮革和纺织品中富马酸二甲酯的方法。试样经乙酸乙酯提取后,在40℃真空旋转蒸发器中浓缩至2.0 mL。用乙酸乙酯稀释定容至50 mL,离心后取1 mL上清液过中性氧化铝固相萃取小柱净化,用乙酸乙酯淋洗定容至2 mL,通过VF-5ms色谱柱分离,采用离子阱的选择离子存储检测模式,结合保留时间、特征离子的相对丰度比及谱库检索信息对富马酸二甲酯进行定性检测,用外标法进行定量分析。富马酸二甲酯质量浓度在0.01~50.0 mg.L-1内与峰面积呈线性关系,检出限(3S/N)为0.02 mg.kg-1。用标准加入法做回收试验,测得平均回收率在80%~92%之间,相对标准偏差(n=6)小于5.5%。     

气相色谱-质谱联用法测定包装膜和包装袋中富马酸二甲酯残留量

提出了气相色谱-质谱联用法测定包装膜和包装袋中富马酸二甲酯残留量的方法。样品中富马酸二甲酯用乙酸乙酯萃取,经针式过滤头净化,采用HP-5MS毛细管色谱柱(30 m×0.25 mm,0.25μm)进行分离。采用气相色谱-质谱电子电离源和全扫描监测模式进行测定。富马酸二甲酯的质量浓度在0.5~100.0 mg.L-1浓度范围与其对应的峰面积呈线性关系,测定下限(10S/N)为0.1 mg.kg-1。在5.0,10.0,20.0,30.0,40.0,50.0 mg.kg-16个添加水平下,富马酸二甲酯的回收率在95.0%~102.5%之间,相对标准偏差(n=6)小于6%。     

糕点中富马酸二甲酯的毛细管气相色谱快速测定

建立了糕点中富马酸二甲酯的毛细管气相色谱快速检测方法.富马酸二甲酯易溶于三氯甲烷,通过超声波提取,用三氯甲烷提取糕点中的富马酸二甲酯,用毛细管气相色谱测定.方法的最低检出限为2.00mg/kg,标准曲线的线性范围:10～500μg/mL,相关系数r为0.999 99,样品加标回收率为93.0%～109.0%,相对标准偏差RSD为1.30%～1.90%.结果表明方法操作简便、快速、回收率高、精密度好,可用于糕点中富马酸二甲酯含量的快速测定.     

气相色谱-质谱法测定皮革中富马酸二甲酯

提出了气相色谱-质谱法(GC-MS)测定皮革中富马酸二甲酯的方法。样品经乙酸乙酯提取后,过中性氧化铝、C_(18)吸附剂、石墨化炭黑净化,在35℃水浴中氮气吹干浓缩至0.2mL。用乙酸乙酯定容至0.5mL,进样1μL,通过DB-5MS色谱柱分离,结合NIST 05标准谱库信息对富马酸二甲酯进行定性检测,用外标法进行定量分析。富马酸二甲酯的质量浓度在0.02～10.0mg·L~(-1)范围内与其峰面积呈线性关系,测定下限(10S/N)为0.02mg·kg~(-1)。以皮革样品为基体加入三种不同浓度的标准溶液按所提方法分析后,计算方法的回收率在84.8%～88.9%之间,相对标准偏差(n=6)在4.3%～5.6%之间。     

气相色谱-质谱法测定塑料制品中1,2-苯二酸-二烷基酯类的含量

建立了测定塑料制品中1,2-苯二酸-二(C6-8支链)烷基酯(富C7)(DIHP)和1,2-苯二酸-二(C7~(-1)1支链与直链)烷基(醇)酯(DHNUP)含量的气相色谱-质谱法。以乙酸乙酯20mL为提取剂提取样品(0.500 0g),于100℃微波萃取30 min,取提取液2.0 mL用乙酸乙酯定容至5.0mL,过滤后,在选择离子监测(SIM)模式下扫描,用气相色谱-质谱法进行测定,以特征碎片离子的丰度比定性,外标法定量。结果表明,DIHP和DHNUP的线性范围均为0.40~4.0 mg·L~(-1),检出限(3S/N)为1.0~2.0 mg·kg~(-1)。按标准加入法进行回收试验,回收率在88.6%~115%之间,相对标准偏差(n=6)均小于5.0%。     

高效液相色谱法测定食品中的富马酸二甲酯

采用高效液相色谱法测定食品中的富马酸二甲酯.样品中的富马酸二甲酯经甲醇提取后,以甲醇-乙酸铵溶液(体积比为55∶45)为流动相,C18色谱柱分离,二极管阵列检测器检测,检测波长为210 nm,外标法定量.方法的线性范围为1～16μg/mL(r=0.99987),检出限为0.1μg/g,测定结果的相对标准偏差为0.54%...     

基质固相分散-气相色谱/质谱法测定蔬菜中的邻苯二甲酸酯

利用基质固相分散-气相色谱/质谱法测定了蔬菜中的邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯、邻苯二甲酸丁基苄基酯和邻苯二甲酸二异辛酯。蔬菜样品经弗罗里硅土和石墨化炭黑研磨均匀后,用乙酸乙酯淋洗净化,结果表明:上述5种邻苯二甲酸酯在0.05~10.00 mg/L 范围内具有良好的线性,样品的添加回收率为76%~90%,相对标准偏差为2%~7%,5种邻苯二甲酸酯的检出限为0.01~0.024 mg/kg。该方法操作简便、经济,分析速度快,适用于大批量样品的分析。     

高效液相色谱法同时测定乳制品中7种防腐剂

采用高效液相色谱法同时测定乳制品中7种防腐剂富马酸二甲酯、纳他霉素、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯和对羟基苯甲酸甲酯异丁酯的含量。样品用甲醇提取,以Symmetry C18色谱柱(4.6mm×25mm,5μm)为固定相,甲醇-0.02mol.L-1乙酸铵(60+40)混合溶液为流动相,用二极管矩阵检测器测定。7种防腐剂在20min内可达到基线分离。7种防腐剂的质量浓度均在1.0～40.0mg.L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)在0.2～0.5mg.kg-1之间。方法用于乳制品分析,加标回收率在87.5%～104%之间,测定值的相对标准偏差(n=6)在2.5%～8.8%之间。     

高效液相色谱法测定海洋涂料中敌草隆和吡啶硫酮铜

提出了高效液相色谱法同时测定海洋涂料中的敌草隆和吡啶硫酮铜含量的方法。海洋涂料样品(0.020 0g)用乙酸乙酯(10mL)超声提取10min。分取1.0mL上清液,加入1mL乙腈混匀后进行色谱分离。以Agilent ZORBAX Eclipse XDB-C18色谱柱为固定相,用乙腈和水以不同比例混合的溶液为流动相进行梯度洗脱,用二极管阵列检测器测定。敌草隆和吡啶硫酮铜的线性范围分别为0.15~800,0.20~200 mg·L-1,检出限(3S/N)为8.0 mg·kg-1(敌草隆)和12.0mg·kg-1(吡啶硫酮铜)。以空白样品为基体在3个浓度水平上进行加标回收试验,所得回收率在90.0%~95.0%之间,测定值的相对标准偏差(n=6)在1.7%~3.4%之间。     

固相萃取-气相色谱法测定饮用水中12种农药

提出了固相萃取-气相色谱法测定饮用水中12种农药残留量的方法。取水样250mL过固相萃取柱,用乙酸乙酯、正己烷各5mL洗脱,经无水硫酸钠脱水,采用DB-5MS毛细管色谱柱分离,电子捕获检测器检测。溴氢菊酯的线性范围为0.05~0.5mg·L-1,其他农药的线性范围均在0.01~0.1mg·L-1。溴氰菊酯的检出限为24.2ng·L-1,其他农药的检出限均低于10ng·L-1。12种农药的加标回收率在70.0%~110%之间,相对标准偏差(n=6)均小于10%。     

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.