浊点萃取-高效液相色谱法同时测定药片与尿样中异烟肼、利福平和吡嗪酰胺

建立了以聚乙二醇(PEG)6000为萃取剂的浊点萃取(CPE)-反相高效液相色谱同时测定异烟肼、利福平和吡嗪酰胺的方法,由于异烟肼不易被浊点萃取方法富集,使异烟肼与对氯苯甲醛在酸性条件下反应衍生为异烟肼腙,异烟肼腙在液相色谱上的信号与异烟肼浓度存在着线性关系.在优化的CPE条件下,采用梯度洗脱的方式,用紫外检测器在310 nm波长下,异烟肼、吡嗪酰胺和利福平的保留时间分别为14.5、34.4和38.1 min,定量范围分别是0.01～10 mg/L、0.08～25 mg/L和0.05～20 mg/L.线性相关系数r>0.99.3种药的平均回收率范围为91.50%～98.75%,精密度(RSD)为 0.22%～1.54%.异烟肼、利福平和吡嗪酰胺的检出限分别为4×10-3、2×10-2和3×10-2 mg/L.本法用于药片和尿样中3种药物的检测,结果满意.     

柱前衍生高效液相色谱-质谱法测定水稻中尼克烟酰胺含量

建立了柱前衍生高效液相色谱-质谱联用(HPLC-MS)测定水稻中尼克烟酰胺含量的方法.样品中尼克烟酰胺经水提取后,与9-芴甲基氯甲酸酯(FMOC-Cl)衍生,采用液相色谱质谱联用仪测定.系统研究了衍生剂浓度和衍生介质等条件对衍生效率的影响.通过优化流动相酸度和梯度洗脱等条件,提高了方法灵敏度.尼克烟酰胺在0.1～5.0 mg/L范围内呈良好的线性关系(r=0.9983),对水稻的根、茎、叶及大米的标准加入实验表明,方法的添加回收率在72.0%～89.2%之间; 相对标准偏差为2.3%～9.6%; 方法检出限为0.05 mg/kg.方法简便、准确可靠,可以满足水稻中生理水平尼克烟酰胺的定性定量分析.     

液相色谱法测定动物源性食品中氯虫苯甲酰胺和氟虫酰胺残留量

采用高效液相色谱法测定动物源性食品中氯虫苯甲酰胺和氟虫酰胺的残留量。动物源性食品中的氯虫苯甲酰胺和氟虫酰胺,经乙酸乙酯和丙酮混合提取液提取后,过Al2O3柱净化,以乙腈:0.1mol/L的乙酸铵溶液(58:42)作为流动相,DAD检测器测定,外标法定量。测定结果表明:采用本方法检测氯虫苯甲酰胺和氟虫酰胺,检测限均可达到0.1mg/kg,在添加质量浓度0.1～2.0mg/L之间线性关系良好,相关系数(r)均>0.9990,对于0.1、0.2、0.5mg/kg水平添加回收率范围在72.3%～92.7%之间;相对标准偏差(RSDs)范围在3.0%～7.0%之间。     

同位素内标超高效液相色谱-串联质谱法检测大鼠血清中丙烯酰胺和环氧丙酰胺

建立了检测大鼠血清中丙烯酰胺和环氧丙酰胺的超高效液相色谱-串联质谱法(UPLC-MS/MS).血清样品中加入乙腈沉淀蛋白质,超高速离心取上清液,离心浓缩后,采用ACQUITY UPLC T3 C18色谱柱(50 mm×2.1 mm, 1.7 μm),以0.1%甲酸溶液和甲醇为流动相进行梯度洗脱,经UPLC分离,电喷雾离子化四级杆串联质谱以正离子多反应监测方式(MRM)检测,用同位素内标法定量.丙烯酰胺和环氧丙酰胺在0.5～20.0 mg/L浓度范围内线性良好,相关系数r均大于0.999;检出限均为0.1 mg/L;在3个浓度水平(2.0, 8.0, 和15.0 mg/L)进行添加实验,样品的加标回收率分别为98.0%～108.3%和99.6%～106.7%;日内精密度(RSD)为0.54%～5.8%和1.1%～5.8%;每个样品测试时间仅为6 min.本方法测定大鼠血清中的丙烯酰胺和环氧丙酰胺操作简单快速, 重现性好, 灵敏度高.     

气相色谱法测定食品包装材料中微量甲醛

建立了食品包装材料中微量甲醛的气相色谱检测方法.样品浸泡液经2,4-二硝基苯肼(DNPH)衍生,正己烷萃取衍生反应物后,气相色谱-电子捕获检测器法测定.采用乙腈多次重结晶法提纯衍生剂(DNPH),以降低DNPH中含有的甲醛衍生产物,避免影响测定;探讨了衍生化反应的条件以及色谱条件.甲醛的残留在0.05～50 mg/L的范围内线性关系良好,检出限为0.05 mg/kg,相对标准偏差为2.7%～5.0%,回收率范围在88.6%～98.0%之间.     

气相色谱法对水果样品中三碘苯甲酸残留的测定

分别选取了苹果、梨等6种水果基质,样品经1%硫酸酸化,用二氯甲烷提取,提取液蒸干后用三甲基硅重氮甲烷进行甲酯化衍生,经弗罗里硅土固相萃取柱净化后上机测定.采用气相色谱,程序升温,电子捕获检测器测定,保留时间定性,外标法定量.优化了衍生条件,并对方法的灵敏度、准确度、精密度和回收率进行了实验,三碘苯甲酸的检出限可达0.000 8 mg/kg,方法在0.01 ～20 mg/L范围内线性关系良好.各浓度水平的添加回收率为63% ～107%,相对标准偏差为1.8% ～9.3%.建立的方法符合国家标准对食品中农药残留测定的要求,可用于对食品安全的监测.     

对甲基苯磺酰氯柱前衍生法测定水中哌嗪

建立了一种高效液相柱前衍生化测定水中哌嗪含量的方法。选取对甲基苯磺酰氯(p-TSC)为衍生试剂对哌嗪进行衍生化,衍生产物利用液质联用(LC-MS)技术定性,高效液相色谱定量分析。方法采用Ultimate XB-C18色谱柱,以甲醇-水(体积比60:40)为流动相,流速为0.8 mL/min,检测波长为240 nm,室温下检测。实验结果表明,哌嗪的衍生化产物与过量衍生化试剂分离良好,在10～100 mg/L的范围内,哌嗪的浓度与其衍生产物峰面积呈现良好的线性关系,相关系数r>0.999。方法的检出限为0.09 mg/L,定量限为0.30 mg/L。回收率范围为88.2%～99.2%,相对标准偏差为2.5%～5.3%。通过正交反应试验确定了最佳衍生化条件:衍生温度为55℃,缓冲液pH为10.0,衍生时间10 min。     

柱后衍生-高效液相色谱法测定玉米中伏马菌素B1和B2

建立了邻苯二甲醛(OPA)柱后衍生-高效液相色谱测定玉米中伏马菌素B1和B2(FB1和FB2)的方法。采用ZORBAX SB-C18色谱柱,以0.1 mol/L磷酸二氢钠溶液(pH 3.3)-甲醇为流动相,梯度洗脱。流动相流速为0.8 mL/min,柱温40 ℃;衍生剂的流速为0.4 mL/min,衍生温度为室温。实验对衍生剂缓冲液的pH、衍生剂的浓度和流速、激发和发射波长等重要条件进行了优化。结果表明,衍生剂的pH在10.5、OPA的质量浓度为2 g/L、流速为0.4 mL/min、激发波长335 nm、发射波长440 nm时测定效果良好,FB1、FB2在0.2～20 mg/L范围内线性关系良好,相关系数大于0.999; FB1和FB2的检出限均为0.02 mg/kg;在0.1～ 4.0 mg/kg范围内,3个添加水平的平均回收率为82.5%～89.8%。该方法精确、简单、快速,适合玉米中FB1和FB2的测定。     

柱后衍生-高效液相色谱-荧光检测法测定面粉中的过氧化苯甲酰

利用过氧化苯甲酰能够在氯化血红素的催化下将底物对羟基苯乙酸氧化成具有荧光的二聚体的性质,建立了柱后衍生-高效液相色谱-荧光检测法测定面粉中过氧化苯甲酰的方法。优化了色谱分离条件和柱后衍生条件,结果表明:催化剂氯化血红素的浓度为8μmol/L,底物对羟基苯乙酸的浓度为80μmol/L,衍生化试剂的pH 10.5,衍生温度为35℃时衍生效率最高。在优化条件下,过氧化苯甲酰的线性范围为0.5～100 mg/L;样品的检出限为1 mg/kg,样品的加标回收率为98.5%～99.5%。本方法与现有的高效液相色谱法相比,检测面粉中过氧化苯甲酰具有抗干扰能力强,灵敏度高。     

非水毛细管电泳-化学发光法测定食品包装材料中酚类环境激素

建立食用包装材料中的双酚A、壬基酚等多种环境激素的非水毛细管电泳-化学发光分析方法.食品包装材料样品浸出物中的双酚A、烷基酚等环境激素经衍生剂DIB-Cl衍生后,经过非水毛细管电泳分离后,分别与过氧草酸酯化学发光反应体系作用,光信号经过光电倍增管接收放大后被检测.以雌二醇(17β-E2)为内标,以相对迁移时间定性,相对发光强度比定量,内标校准曲线法测定样品浸出物中待测物的含量.对影响非水毛细管电泳分离如溶剂组成和比例、电解质浓度、温度、乙酸浓度、电泳电压等条件进行了优化.同时对化学发光体系也进行了优化.4-叔丁基酚、双酚A、4-叔辛基酚、4-壬基酚和四溴双酚 A分别在0.0095～3.0 mg/L, 0.0087～3.0 mg/L, 0.0085～3.0 mg/L, 0.011～3.0 mg/L和0.009～3.0 mg/L范围内线性良好,r＞0.9947.相对迁移时间和相对峰高的RSD分别为0.88%～2.96%和 6.54%～8.57%.加标回收率为86.7%～98.8%.对5种常见的食品包装材料样品进行了测定, 所建立的方法简便、快速、灵敏,适合于食品包装材料中酚类环境激素的检测.     

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%.     

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.     

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.     

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.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

关于"对‘燃料电池物理及化学性能的有限时间热力学分析方法'的讨论”答复

把有限时间热力学理论用于化学过程的研究,将会得到一系列新的结论,开展这方面的研究是很有意义的.文献[1]以燃料电池为例,在同时考虑化学反应及传热不可逆性的情况下,研究了燃料电池的性能界限,文献[2]指出了文献[1]计算化学反应及传热不可逆性而引起系统与有关环境的总熵产生率的错误以及由此而导致的结论所存在的问题,并进行了富有启发性的分析与讨论.但文献[2]对于系统与有关环境的总熵产生率的计算也是不正确的,由此得到的其它结论自然不能成立.本文将就此情况下系统与有关环境的总熵产生率的计算再次进行讨论,并给出电池功率和效率的有限时间热力学性能界限.