高效液相色谱法测定均苯四甲酸及杂质

通过优化了色谱工作条件建立了测定均苯四甲酸及杂质的高效液相色谱分析方法。结果表明:在柱温为35℃条件下,以pH为1.9的乙腈-0.1%(φ)磷酸溶液(25+75)混合液为流动相,1.0mL·min-1流速下等度洗脱,于波长237nm下测定,外标法定量,均苯四甲酸及杂质实现了基线分离,分离度2。峰面积与质量浓度间呈线性关系;检出限在0.03~0.08mg·L-1之间;测定下限在0.07~0.22mg·L-1之间,测定值的相对标准偏差(n=5)小于2%。     

高效液相色谱法测定化妆品中7种甘草成分

建立了一种测定化妆品中7种甘草成分的高效液相色谱法。样品经甲醇(7+3)溶液提取,采用ODS-2HYPERSIL色谱柱进行分离,以乙腈-0.05%(φ)磷酸溶液为流动相进行梯度洗脱,采用光电二极管阵列检测器在237nm处进行检测。7种组分的质量浓度在1~200mg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)在0.6~1.0ng之间。对空白样品进行加标回收试验,回收率在92.5%~103%之间,测定值的相对标准偏差(n=6)在0.09%~1.8%之间。     

基质固相分散-高效液相色谱法测定蜂巢中7种黄酮类化合物

采用基质固相分散-高效液相色谱法(MSPD-HPLC)同时测定蜂巢中芦丁、桑色素、木犀草素、槲皮素、芹菜素、白杨素和山奈素的含量。以硅胶为基质固相分散剂与样品混合均匀后装柱,以甲醇为洗脱剂进行洗脱。洗脱液在Pinnacle II C18分离柱上分离,以乙腈-0.2%(φ)磷酸溶液为流动相进行梯度洗脱,检测波长为260nm。7种黄酮类化合物的质量浓度在一定范围内与峰面积呈线性关系,检出限(3S/N)在0.07~0.32mg·L-1之间。方法用于测定蜂巢中7种黄酮类化合物,加标回收率在84.9%~95.9%之间,测定值的相对标准偏差(n=6)在2.3%~6.3%之间。     

磷锑钼蓝分光光度法测定氟硅酸中的磷酸根

建立磷锑钼蓝分光光度法测定氟硅酸中磷酸根含量的方法。在氟硅酸样品中加入高氯酸高温挥发除去HF、SiF_4等挥发性的物质,在弱酸性的介质中磷与锑、钼酸铵形成杂多酸,用抗坏血酸还原为磷锑钼蓝络合物,用分光光度计在705nm波长下测定氟硅酸中磷酸根含量。研究了测定波长、样品酸度、还原剂浓度、还原时间、酒石酸锑钾用量、干扰元素对测定结果的影响,并确定了最佳分析条件:测定波长为705 nm,盐酸溶液(1+1)加入量为1.3 mL,酒石酸锑钾溶液(3 g/L)加入量为0.5 mL,抗坏血酸溶液(20 g/L)加入量为1.5 mL,还原时间为10 min。在此实验条件下,磷酸根的质量浓度在0～15 μg/mL与吸光度具有良好的线性关系,线性相关系数为0.999 8,检出限为0.051μg/mL。测定结果的相对标准偏差为2.27%～2.38%(n=11),加标回收率为97.34%～102.72%。该方法操作简单,测试结果准确度和精密度较高,可满足氟硅酸中磷酸根含量的测定,用于氟硅酸生产的质量控制。     

高效液相色谱法测定植物果实中儿茶素、表儿茶素和原花青素B_2

提出了高效液相色谱法测定植物果实中儿茶素、表儿茶素和原花青素B2。样品经乙醇(6+4)溶液索氏提取后,用固相萃取技术对提取液进行净化。以SinoChrom ODS C18色谱柱为分离柱,以乙腈-0.1%(φ)磷酸溶液(15+85)为流动相进行洗脱,检测波长为280nm。3种目标分析物质量浓度的线性范围为5.0~100.0mg·L-1,方法的检出限(3S/N)在1.03~2.38mg·L-1之间。对样品进行加标回收试验,回收率在83.6%~98.5%之间,测定值的相对标准偏差(n=3)在0.4%~2.1%之间。     

偏最小二乘紫外分光光度法同时测定丁烯二酸的顺反异构体

将偏最小二乘法用于紫外分光光度分析,在pH=1.4的磷酸溶液中,同时测定了丁烯二酸的顺、反异构体。确定了测定的最佳波长范围为190～268nm;测得23个混合标样的吸光度值用于建立模型,顺、反丁烯二酸的浓度范围为3.0～14.0mg/L和1.0～13.0mg/L。所建立的测定二者模型的相关系数分别为0.9951和0.9983;平均回收率分别为100.8%和100.7%;均方根误差(RMSE)分别为0.3667和0.2233;预测相对误差(REP)分别为5.05%和3.49%。对3个批次反丁烯二酸样品的测定结果与高效液相色谱法的测定结果进行比较,经成对t检验表明,两种方法的测定结果无显著性差异。     

离子色谱法测定浓磷酸中的Cl~–,SO_4~(2–),NO_3~–

采用离子色谱法测定浓磷酸中的Cl~–,SO_4~(2–),NO_3~–。将浓磷酸稀释至400倍体积,以0.22μm滤膜过滤,使用阴离子交换色谱–抑制电导检测器测定浓磷酸中的Cl~–,SO_4~(2–),NO_3~–。采用高容量色谱柱,以1.0 mmol/L Na_2CO_3–24 mmol/L Na OH混合液为流动相,将无机阴离子与浓磷酸基体分离,以标准加入法定量。氯离子、硝酸盐、硫酸盐的检出限为0.05~0.12 mg/L,加标回收率为96.6%~100.0%,测定结果的相对标准偏差为7.0%~10.0%(n=5)。该方法分离效果好,可用于浓磷酸中Cl~–,SO_4~(2–),NO_3~–的同时测定。     

向日葵仁中绿原酸和咖啡酸的反相高效液相色谱法测定

建立了同时测定向日葵仁中绿原酸和咖啡酸的反相高效液相色谱法 ;采用美国Alltech公司的ALLTIMAC18 柱(250mm×4.6mmID,5μm) ,流动相为乙腈 -2 %(φ)乙酸溶液 (体积比15∶85) ,流速为1.0mL/min ,紫外检测波长327nm ;向日葵仁中绿原酸(chlorogenicacid)和咖啡酸(caffeicacid)在18min内得到很好的分离 ,该法简便、快速、结果准确、重复性好。     

电感耦合等离子体发射光谱法测定湿法精制磷酸中镁、钙、铁、砷含量

采用电感耦合等离子体发射光谱法(ICP-OES)测定湿法精制磷酸中微量元素镁、钙、铁、砷含量,对仪器参数及元素谱线等相关参数进行实验和优化,方法具有线性范围宽、精密度高、结果准确、分析速度快等特点。相对标准偏差RSD为0.26%～0.82%,加标回收率为95.75%～102.8%,检出限为0.0021～0.0408mg/L,适用于湿法精制磷酸中镁、钙、铁、砷的测定。     

对氯苯酚提取-液相色谱法分析烟草中的磷酸腺苷

建立了新鲜烟叶中三磷酸腺苷(ATP)、二磷酸腺苷(ADP)和单磷酸腺苷(AMP)3种磷酸腺苷同时测定的方法。烟草样品经过对氯苯酚提取、纯化后,采用三乙胺缓冲液作为流动相洗脱,经C18色谱柱分离,在259 nm波长对样品进行检测。与高氯酸(PCA)法,以及DNA常用的苯酚提取法进行了比较,结果均表明:低温下以对氯苯酚提取的效果较佳,使用三乙胺缓冲液流动相具有分离效率高、检出灵敏的优点。在线性范围(5~200μg/mL)内,磷酸腺苷浓度与峰面积具有很好的相关系数(r>0.9999),检出限达到纳克级水平,氯苯酚法对ATP,ADP和AMP的平均回收率分别为96.8%,97.2%和93.3%,RSD均小于5%。     

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.     

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.     

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.     

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.