高效液相色谱法测定保健食品中的黄芪甲甙

以Waters Nova-Pak C18柱为色谱柱，乙腈－水（体系比为1：2）为流动相，Waters-2996二极管阵列检测器为检测器，对保健食品中的黄芪甲甙进行高效液相色谱分析。线性回归方程为A＝89852c-22076，相关系数r=0。9997,线性范围为5.0-50.0μg/mL，回收率为97.2%-98.9%，相对标准偏差为1.38%-1.61%。方法简便，灵敏度高，重现性好。     

反相离子对高效液相色谱法测定硫酸软骨素

以四甲基氯化铵作为离子对试剂，采用乙腈-2.28mmol/L四甲基氯化铵水溶液（5:95)作为流动相，选用C18色谱柱分离硫酸软骨素和杂质，建立了测定硫酸软骨素含量的反相离子对高效液相色谱方法。该方法的线性范围为0.4-8.0μg，回收率为98.8%-100.3%，相对标准偏差为0.17%-0.53%。该方法的精密度和准确度较高。     

高效液相色谱-串联质谱法测定猪组织中的土拉霉素

建立了高效液相色谱-串联质谱法测定土拉霉素在猪肝脏、肾脏、肌肉、皮脂和肺脏中的残留检测方法,并初步探讨了土拉霉素的基质效应.样品用乙腈提取,涡旋振荡离心后经正己烷脱脂,C18固相萃取柱净化后,40℃氮气吹干,用50%乙腈定容.以Penomenex Luna C18柱为色谱柱,乙腈-2 mmol,/L乙酸铵水溶液(含0....     

液相色谱法测定鳗鱼中的孔雀石绿

用高效液相色谱法测定鳗鱼组织中孔雀石绿的残留量。鱼体中残留的孔雀石绿在酸性介质下，经高速均质后，用乙腈均质提取，合并提取液，用二氯甲烷再次萃取，有机相过无水硫酸钠和氧化铝复合小柱后浓缩至干，用盐酸羟胺和流动相定容。以乙酸盐缓冲溶液和乙腈为流动相，在KR60－5氰柱上分离后，用可见光检测器在618nm处测定吸光强度，外标法定量。其检出限为1μg/kg，回收率为93.5%-99.6%，相对标准偏差RSD为6.54%-11.0%。     

高效液相色谱法测定鸡肝中玉米赤霉醇的残留量

建立了高效液相色谱测定鸡肝中玉米赤霉醇的方法。样品经β-葡糖苷酸酶水解、乙醚提取、氢氧化钠抽提、C18小柱净化后,用Zorbax SB-Phenyl柱(250 mmx4.6 mm i.d., 5 μm)分离,以乙腈-0.3%三氟乙酸水溶液(体积比为40∶60)作流动相,流速为0.80 mL/min,于262 nm波长处检测。结果表明,样品的加标平均回收率为72.0%-80.4%,相对标准偏差为8.3%-13.9%,定量测定低限(LOQ)为5 μg/kg。方法已应用于实际样品的测定。另外,用高效液相色谱-质     

高效液相色谱法快速测定生物样品中的视黄酸

建立了快速测定生物样品中全反式(all-trans-),9-顺式(9-cis-),13-顺式(13-cis-).视黄酸(RA)的高效液相色谱分析方法.经2次液-液萃取提取生物样品中的视黄酸后.直接应用高效液相色谱法同时测定了3种视黄酸同分异构体的含量.采用Waters C18反相柱(3.9×150mm),V(乙腈):V(0.1%冰醋酸溶液)=86:14为流动相,流速1.0 mL/min,柱温为25℃,检测波长为350 nm.3种视黄酸同分异构体的线性范围均为5-500 ng/mL,r2均大于0.999;检出限均为1 ng/mL;提取回收率为92.7%-101.8%,方法回收率为102,4%-104.4%;日内精密度小于8.3%,日间精密度小于11%.本方法适用于不同生物样品中视黄酸的定量研究.     

高效液相色谱法测定水产品中7种兽药残留量

提出了高效液相色谱法同时测定水产品中呋喃唑酮、噁喹酸、萘啶酸及4种磺胺类药物等7种兽药残留量的方法。样品经乙腈提取,正己烷脱脂,用中性氧化铝柱和C18固相萃取柱进行分离及净化。以Symmetry C18色谱柱为分离柱,以不同体积比混合的乙腈与0.08mol.L-1乙酸溶液为流动相进行梯度洗脱,紫外检测器于波长265nm处检测。7种兽药的质量浓度与其峰面积均在0.05～1.0mg.L-1范围内呈线性关系,检出限(3S/N)为0.01～0.04mg.kg-1。方法的回收率在68.2%～97.3%之间,相对标准偏差(n=6)在1.6%～14%之间。     

超高效液相色谱-串联质谱法同时测定调味料中的17种防腐剂和抗氧化剂

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定调味料中11种防腐剂和6种抗氧化剂的定性、定量分析方法。低脂肪和中等脂肪含量的调味料样品用饱和NaCl水溶液(用磷酸调pH为2～3)稀释混合均匀,然后用乙腈提取,正己烷液-液萃取净化(中等脂肪含量的样品提取液还需经C8固相萃取柱进一步的净化处理);脂肪含量高的样品先用正己烷稀释,再用饱和NaCl水溶液(用磷酸调pH为2～3)溶解样品,然后用乙腈提取,提取液进一步经C8固相萃取柱净化处理。提取液经C18反相色谱柱(150 mm×2.1 mm, 1.7μm)分离,流动相为20 mmol/L乙酸铵水溶液和乙腈,梯度洗脱,以电喷雾离子源负离子多反应监测(MRM)模式进行MS/MS检测。17种分析物在线性范围内具有较好的线性关系,相关系数r≥0.9955,其定量限(LOQ,信噪比为10)为0.05～5 mg/kg;空白样品中的添加回收率为79.7%～118%,精密度(以相对标准偏差计)为0.57%～13.1%。该方法适用于调味品中防腐剂和抗氧化剂的检测。     

HPLC法测定丙酮酸钙的含量

建立一种用高效液相色谱法(HPLC法)测定丙酮酸钙含量的方法。色谱条件为C18柱,乙腈—0.1%二环已胺和0.1%甲酸的水溶液(5:95)为流动相, 检测波长为230nm。线性范围0.08~0.8mg/mL(r = 0.9999)。     

高效液相色谱法测定黄瓜和油菜中的啶虫脒残留量

建立了一种高效液相色谱测定黄瓜和油菜中啶虫脒农药残留的方法。以乙腈提取,弗罗里硅土净化,采用Agilent 1100高效液相色谱仪带DAD检测器对待测组份进行了分离和测定,检测波长254 nm,使用C18不锈钢反相柱（250 mm×4.6 mmi.d.,5μm）,以V（乙腈）∶V（水）=30∶70作流动相,啶虫脒在0.05-2.00mg/L范围内呈良好的线性关系（r=0.9999）,方法的添加回收率范围为73.7%-85.6%。RSD为2.2%-10.3%,能够满足啶虫脒在黄瓜和油菜中残留分析的要求。     

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.