胶束增敏紫外分光光度法测定甲砜霉素的研究

用紫外分光光度法对pH 6.00Na2 HPO4-NaH2 PO4的缓冲介质中甲砜霉素和溴化十六烷基三甲铵( CTMAB)形成的胶束配合物的性能进行了研究.利用胶束的增敏增稳作用,提出了测定甲砜霉素的紫外分光光度新方法,方法线性范围为0.25～95 μg/mL,检出限为0.12 μg/mL.已应用于片剂中甲砜霉素的测定...     

溴甲酚绿与甲砜霉素的显色反应及应用

在pH 4.0～5.3的条件下,甲砜霉素与溴甲酚绿反应生成具有1个正吸收峰和2个几乎相等的负吸收峰的离子缔合物。最大正吸收波长位于610 nm,2个负吸收波长分别位于652 nm和574 nm,表观摩尔吸光系数分别为2.16×104 L.mol-1.cm-1(正吸收),1.36×104 L.mol-1.cm-1(652 nm负吸收)和1.32×104 L.mol-1.cm-1(574 nm负吸收),线性范围均为0～5.3 mg/L。甲砜霉素在一定浓度范围内遵从朗伯比尔定律,由此建立了测定甲砜霉素的正吸收、负吸收及双波长叠加吸收光谱法。方法已用于人体尿液、血液及市售药物中甲砜霉素含量的测定。     

高效液相色谱-串联质谱法同时测定水产品中氯霉素、甲砜霉素和氟甲砜霉素的残留量

建立了水产品中氯霉素、甲砜霉素和氟甲砜霉素药物残留量同时测定的高效液相色谱-串联质谱方法。以氘代氯霉素做内标,选择乙酸乙酯提取,HLB固相萃取柱净化,洗脱液氮气吹干,采用LC-MS/MS选择反应监测(SRM)负离子模式进行定性、定量分析。结果表明:氯霉素的检出限(LOD)为0.01μg/kg,甲砜霉素和氟甲砜霉素检出限(LOD)为0.03μg/kg,检测结果的相对标准偏差为3.3%～9.7%(n=6),加标回收率达到78.6%～110.5%。该方法在水产品中氯霉素、甲砜霉素和氟甲砜霉素药物的残留测定中具有很好的应用前景。     

曙红Y分光光度法测甲砜霉素的含量

甲砜霉素(TAP)与曙红Y(EOSY)在pH＝1.52的酸性介质中相互反应生成离子缔合物,可使体系吸光度增大.最大吸收波长位于482 nm,表观摩尔吸光系数(ε)为4.27×10 4 L·mol-1·cm-1,甲砜霉素浓度在0.18～5.3 mg·L-1范围内遵从比尔定律,据此建立了以曙红Y为探针测定甲砜霉素的分光光度法.该法简便快速,有较高灵敏度,可用于实际样品中甲砜霉素的测定.     

高效液相色谱/串联质谱法同时测定虾中氯霉素、甲砜霉素和氟甲砜霉素残留量

用高效液相色谱／串联质谱(LC／MS,／MS)同时测定虾中的氯霉素(CAP)、甲砜霉素(TAP)和氟甲砜霉素(FF)。均质后的虾样品,采用碱化乙酸乙酯提取。浓缩提取物经液．液分配(LLP)去除脂肪,C18固相萃取(SPE)柱净化后,采用LC／MS／MS电喷雾电离(ESI),负离子,多反应监测(MRM)模式检测,外标法定量。检出限为：氯霉素和氟甲砜霉素0．01ng/g;甲砜霉素为0．05ng／g。在添加浓度0．1～2．0ng/g范围内,氯霉素回收率为73．9％～96．0％;甲砜霉素回收率为78．6％～99．5％;氟甲砜霉素回收率为74．9％～103．7％;相对标准偏差(RSD)均小于6．4％。     

超高效液相色谱-串联质谱法测定畜禽副产品中氯霉素和氟甲砜霉素残留量

建立了超高效液相色谱-串联质谱测定畜禽副产品中氯霉素和氟甲砜霉素残留量的方法。样品经碱性乙酸乙酯提取,正己烷脱脂后,直接采用电喷雾电离(ESI)多反应监测(MRM)负离子模式检测,氯霉素用同位素内标定量,氟甲砜霉素用外标法定量。氯霉素和氟甲砜霉素在0.2～50μg/L范围内线性良好,相关系数达到0.9999;检出限均为0.04μg/kg;氯霉素回收率为89.6%～112.0%,RSD为5.4%～8.1%;氟甲砜霉素回收率为90.3%～110.0%,RSD为5.1%～8.0%。方法可用于畜禽副产品中氯霉素和氟甲砜霉素残留量测定。     

超高效液相色谱法测定水产品中甲砜霉素和氟甲砜霉素残留

建立了一种同时测定水产品中甲砜霉素和氟甲砜霉素药物残留的超高效液相色谱(UPLC)方法。样品经乙酸乙酯提取,正己烷液-液分配除脂,过HLB固相萃取小柱,用3mL10%甲醇淋洗,5mL100%甲醇洗脱,洗脱液用氮气吹干,残渣用1mL10%乙腈水溶液定容。采用超高效液相色谱分离,二极管阵列检测器检测,外标法定量。甲砜霉素在0.05~2.0mg/L,氟甲砜霉素在0.025~1.0mg/L范围线性关系良好,相关系数分别为0.9996、0.9999;样品加标平均回收率分别为80.0%、95.8%;相对标准偏差分别为5.6%、11.2%,甲砜霉素、氟甲砜霉素检出限分别为10μg/kg、5μg/kg。     

超高效液相色谱串联质谱法测定蜂蜜中氯霉素、氟甲砜霉素、甲砜霉素、甲硝唑

建立液相色谱串联质谱法测定蜂蜜中氯霉素、氟甲砜霉素、甲砜霉素和甲硝唑的分析方法。试样经乙酸乙酯提取,MCX固相萃取柱净化,选择Kinetex C_(18)型(100 mm×2.1 mm,2.6μm)色谱柱,以乙腈与5 mmol/L乙酸铵溶液(含0.05%甲酸)流动相进行梯度洗脱,流量为0.4 mL/min,进样体积为10μL。采用多反应监测(MRM)模式检测,以氯霉素-D_(5)和甲硝唑-D_(4)为内标,采用超高效液相色谱–串联质谱法测定。4种抗生素的质量浓度在0.25-10μg/L范围内与各自的色谱峰面积线性关系良好,线性相关系数均大于0.995,检出限为0.08μg/L。测定结果的相对标准偏差为3.7%-8.9%(n=6),平均加标回收率为90.2%-105.7%。该方法适用于蜂蜜中氯霉素、氟甲砜霉素、甲砜霉素、甲硝唑的检测。     

超高效液相色谱-串联质谱法测定禽蛋中氯霉素、甲砜霉素和氟甲砜霉素

采用超高效液相色谱-三重四极杆串联质谱,用多反应监测模式定量,建立了禽蛋中氯霉素、甲砜霉素和氟甲砜霉素同时测定的分析方法。添加氯霉素-d5作为内标进行定量,试样经过乙酸乙酯提取,三氯乙酸去蛋白,盐析,分离,再经正己烷去脂肪,省去固相萃取净化步骤,直接上机测定。氯霉素、甲砜霉素和氟甲砜霉素的检出限分别为0.03,0.03和0.015"g/kg,定量限分别为0.10,0.10和0.05"g/kg,3种化合物的加标平均回收率在90.5%~103.5%,相对标准偏差在2.1%~6.0%之间。方法能对禽蛋中的氯霉素类化合物进行检测分析。     

动物源性食品中3类抗生素类药物残留检测

建立了利用固相萃取方法和高效液相色谱法检测猪肌肉中土霉素、甲砜霉素、磺胺甲氧哒嗪的残留的方法.固相萃取技术能快速有效的提取动物源性食品中的抗生素残留.建立的高效液相色谱法在5 ～ 1000 μg/L范围内线性良好(R＞0.999),土霉素、甲砜霉素、磺胺甲氧哒嗪的平均回收率分别为78.6％ ～ 86.2％,77.8％ ...     

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.