反相高效液相色谱法测定西荞3号黄酮含量

利用反相高效液相色谱法测定西乔3号中芦丁、槲皮素中成分的含量。采用SHIMDZU VP-ODS(4.6 mm×150 mm,5.0μm)色谱柱,甲醇-0.08%:磷酸溶液(6∶4)为流动相,流量为0.95 mL.min-1,检测波长为358 nm。待测组分与其他组分分离度良好(R>1.5),芦丁和槲皮素线性范围分别为32.0～288.0μg.ml-1和18.8～169.26μg.ml-1,平均回收率分别为98.5%,99.0%,相对平均偏差(n=5)分别为0.4%,0.4%。     

固相微萃取-加压毛细管电色谱测定痕量丙烯酰胺

联合运用固相微萃取和加压毛细管电色谱(pCEC)方法测定水中痕量丙烯酰胺.以活性炭吸附富集样品中的丙烯酰胺,甲醇洗脱,萃取回收率稳定,平均为59.0%,萃取体积比可达到100倍,因此获得约60倍的富集效率.萃取洗脱液用配有紫外检测器的加压毛细管电色谱仪测定,标准曲线法定量.方法的线性下限浓度为5ng/ml,线性关系良好,相关系数r=0.999.     

超声波辅助固相萃取高效液相色谱法测定橡胶中的MBT

建立一种快速溶剂萃取—高效液相色谱检测橡胶中的2-巯基苯并噻唑(MBT)含量的方法.采用超声波辅助丙酮溶解橡胶样品,再采用C18固相萃取小柱萃取其中的MBT,并选择合适的高效液相色谱条件分离测定MBT.选用Zorbax eclipse XDB C18液相色谱柱,V甲醇∶V水∶V0.1%甲酸=60∶35∶5为流动相,紫外波长320 nm进行检测.通过考察最佳预处理萃取条件和高效液相色谱条件下MBT含量的色谱图,根据色谱峰面积采用外标法进行定量分析,MBT的浓度在1.0～12.0 ppm范围内呈良好线性,回归方程为A=-15.1+71.2C(C的单位为ppm),相关系数:r=0.99951,标准回收率为95%～106%.该方法可用于橡胶样品中MBT的测定.     

固相萃取-高效液相色谱法测定茶叶中儿茶素

建立一种用高效液相色谱法测定茶叶中儿茶素的含量.方法:样品经乙醇提取,超声30min后,过C18小柱净化,样品溶液经0.45μm滤膜过滤后,用于HPLC分析.使用C18(5 um,150 mm×6.0 mm)色谱柱进行分离,用不同体积比混合的流动相A及流动相B的混合液作梯度淋洗,流速为1.0 ml/min,检测波长为280 nm,柱温为40℃.以甲醇∶水∶乙酸-26∶73.5∶0.5(体积比)为流动相.儿茶素在0.02～0.3 g/L范围内线性关系良好,回收率在98.2%～100.3%之间,相对标准偏差为1.6643%.该方法具有操作简便、快速、精密度高、回收率好、重现性较好、检测限低等优点.     

黄茶挥发性成分的HS-SPME-GC/MS分析

报道了采用顶空固相微萃取技术(HS-SPME)提取黄茶中挥发性化学成分,用气相色谱-质谱法(GC/MS)从黄茶挥发油中分离并确定出30种化学成分,其中主要成分为苯甲醇(9.25%)﹑苯乙醇(4.03%)和二甲基硫醚(3.39%).     

微波辅助低共熔溶剂萃取高效液相色谱法测定山楂中芦丁和槲皮素

建立了一种利用微波辅助低共熔溶剂(Deep eutectic solvent, DES)萃取结合高效液相色谱(high performance liquid chromatography, HPLC)测定山楂中芦丁和槲皮素的新方法。利用合成的8种DES和纯水、甲醇做为萃取剂,考察了微波萃取时间及功率、萃取剂种类、固液比、DES含水量以及离心时间等因素对萃取效率的影响,对萃取的机理进行了研究。结果显示,当萃取剂选择n(三丁基苄基氯化铵):n(甘油)=1:2,固液比为0.01 g/mL,DES含水量为60%,微波功率为640 W时,仅用80 s就可以高效提取山楂中的芦丁和槲皮素,在浓度0.25～10.0μg/mL范围内具有良好的线性关系(R² ≥0.9993),检测波长选择360 nm,芦丁和槲皮素的检出限(LOD)分别为11.2和8.5μg/L,样品平均加标回收率为95.7%～105.2%,相对标准偏差(RSD)小于3.7%。本方法不需使用传统有机溶剂,环境友好,与其他萃取方法相比,萃取效率高,成功应用于不同产地实际山楂样品的测定中,结果满意。     

高效液相色谱法同时测定部分化妆品中的酸性橙7和碱性嫩黄O

建立了化妆品中酸性橙7和碱性嫩黄O的高效液相色谱法。方法以甲醇为萃取溶剂,过0.45μm滤膜过滤后,以0.02 mol/L乙酸铵和甲醇经反相色谱柱梯度洗脱后,采用二极管阵列检测器检测,并用外标法定量计算。在5.0~20.0 mg/kg的添加水平,回收率在83.9%~94.0%之间,变异系数在4.4%~7.2%之间。     

反相高效液相色谱法测定公丁香中芦丁和槲皮素的含量

采用超声辅助提取,建立公丁香中芦丁和槲皮素的反相高效液相色谱分析方法。色谱柱为Kromasil C18柱(4.6 mm×250 mm,5μm),流动相为CH_3OH∶H_2O∶CH_3COOH(50∶50∶0.1),紫外检测波长360 nm,流速0.8 m L·min^(-1),色谱柱柱温为25℃。芦丁进样范围在0.33~6.60μg时,与色谱峰面积呈良好的线性关系(r=0.9980),平均回收率为96.7%,RSD为1.5%(n=6);槲皮素进样范围在0.35~7.00μg时,与色谱峰面积呈良好的线性关系(r=0.9991),平均回收率为96.0%,RSD为1.6%(n=6)。建立的反相高效色谱法操作简便,定量准确,可用于公丁香中芦丁和槲皮素的含量测定。     

筋骨草中槲皮素成分的含量测定

采用高效液相色谱法对筋骨草中槲皮素的含量进行测定。色谱条件为:色谱柱,Hypersil ODS(5μm,250.0×4.0mm);流动相,pH=2.08磷酸:甲醇为45:55;检测波长为370nm。标准曲线显示,槲皮素在2.24—22.40μg·mL-1范围内呈良好的线性关系,回归方程为y=192.0x+202.4,r=0.998。样品平均回收率为97.6%,RSD为1.67%,这表明本法是一种筋骨草中槲皮素的分析及含量测定的简便、快速、准确且重现性好的方法。     

高效液相色谱法测定银杏叶分散片中槲皮素含量

目的:建立以高效液相色谱法测定银杏叶分散片中槲皮素含量的方法.方法:用十八烷基硅烷键合硅胶为填充荆;以甲醇-0.4%磷酸溶液(50:50)为流动相;流速为1.0ml/min;检测波长360nm;柱温35℃.结果:该法线性关系良好,加样平均回收率为99.38%,RSD为0.72%.结论:该法操作简便、分离效果好,结果准确、精密度高、重现性好,可作为该制剂的质量控制方法.     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

汉字倒说

汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Social and Cultural Influence on Word Meaning

Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language.     

钱生钱!

我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.