270 resultados para RP-HPLC


Relevância:

60.00% 60.00%

Publicador:

Resumo:

运用RP-HPLC建立了花锚中青兰苷、去甲氧基花锚苷和花锚苷的含量分析方法,为栽培花锚替代野生花锚入药提供一定的科学依据.花锚苷、去甲氧基花锚苷和青兰苷分别在0.68~3.40 μg(r=0.999 8)、0.36~1.80 μg(r=0.999 0)和0.80~4.00 μg(r=0.997 9)有良好线性关系,平均回收率分别为100.39% (RSD=2.60%)、99.79% (RSD=3.55%)和100.71% (RSD=2.19%).栽培花锚中花锚苷和去甲氧基花锚苷的含量(抗肝炎活性成分)和在野生花锚中的含量相比无明显差别,可以初步证明栽培花锚可以替代野生花锚入药.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Reversed-phase high-performance liquid chromatographic (RP-HPLC) retention parameters, which are determined by the intermolecular interactions in retention process, can be considered as the chemical molecular descriptors in linear free energy relationships (LFERs). On the basis of the characterization and comparison of octadecyl-bonded silica gel (ODS), cyano-bonded silica gel (CN), and phenyl-bonded silica gel (Ph) columns with linear solvation energy relationships (LSERs), a new multiple linear regression model using RP-HPLC retention parameters on ODS and CN columns as variables for estimation of soil adsorption coefficients was developed. It was tested on a set of reference substances from various chemical classes. The results showed that the multicolumn method was more promising than a single-column method was for the estimation of soil adsorption coefficients. The accuracy of the suggested model is identical with that of LSERs.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Post-transcriptional modifications in RNA give rise to free modified ribonucleosides circulating in the blood stream and excreted in urine. Due to their abnormal levels in conjunction with several tumor diseases, they have been suggested as possible tumor markers. The developed RP-HPLC method has been applied to analyze the urinary nucleosides in 34 urinary samples from 15 kinds of cancer patients. The statistical analyses showed the urinary nucleoside excretion, especially modified nucleoside levels, in cancer patients were significantly higher than those in normal healthy volunteers. Factor analysis was used to classify the patients with cancer and normal healthy humans. It was found that using 15 urinary nucleoside levels or only five modified nucleoside levels as data vectors the factor analysis plot displayed two almost separate clusters representing each group. (C) 1999 Elsevier Science B.V. All rights reserved.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

2-(2-Phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA) and 2-(9-acridone)-acetic acid (AAA), two novel precolumn fluorescent derivatization reagents, have been developed and compared for analysis of primary aromatic amines by high performance liquid chromatographic fluorescence detection coupled with online mass spectrometric identification. PPIA and AAA react rapidly and smoothly with the aromatic amines on the basis of a condensation reaction using 1-ethyl-3-(3dimethylaminopropyl)-carbodiimide (EDC) as dehydrating catalyst to form stable derivatives with emission wavelengths at 380 and 440 nm, respectively. Taking six primary aromatic amines (aniline, 2-methylaniline, 2-methoxyaniline, 4-methylaniline, 4-chloroaniline, and 4-bromoaniline) as testing compounds, derivatization conditions such as coupling reagent, basic catalyst, reaction temperature and time, reaction solvent, and fluorescent labeling reagent concentration have also been investigated. With the better PPIA method, chromatographic separation of derivatized aromatic amines exhibited a good baseline resolution on an RP column. At the same time, by online mass spectrometric identification with atmospheric pressure chemical ionization (APCI) source in positive ion mode, the PPIA-labeled derivatives were characterized by easy-to-interpret mass spectra due to the prominent protonated molecular ion m/z [M + H](+) and specific fragment ions (MS/MS) m/z 335 and 295. The linear range is 24.41 fmol-200.0 pmol with correlation coefficients in the range of 0.9996-0.9999, and detection limits of PPIA-labeled aromatic amines are 0.12-0.21 nmol/L (S/N = 3). Method repeatability, precision, and recovery were evaluated and the results were excellent for the efficient HPLC analysis. The most important argument, however, was the high sensitivity and ease-of-handling of the PPIA method. Preliminary experiments with wastewater samples collected from the waterspout of a paper mill and its nearby soil where pollution with aromatic amines may be expected show that the method is highly validated with little interference in the chromatogram.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

针对广泛应用于超燃冲压发动机的吸热碳氢燃料,简要介绍了用于模拟燃料热物理特性的替代燃料方法和广义对应状态法则.以大庆RP-3航空煤油为例,选择了一个由49%(摩尔比)正十烷,44%1,3,5-三甲基环己烷以及7%正丙基苯组成的替代煤油用来模拟RP-3航空煤油进行热物理特性研究,并采用广义对应状态法则对替代煤油热力学和输运特性进行了数值研究.在此基础上,提出了预测超临界态流体通过音速喷管流量的新方法并得到了实验验证.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

针对广泛应用于超燃冲压发动机的吸热碳氢燃料,简要介绍了用于模拟燃料热物理特性的替代燃料方法和广义对应状态法则.以大庆RP-3航空煤油为例,选择了一个由49%(摩尔比)正十烷,44%1,3,5-三甲基环己烷以及7%正丙基苯组成的替代煤油用来模拟RP-3航空煤油进行热物理特性研究,并采用广义对应状态法则对替代煤油热力学和输运特性进行了数值研究.在此基础上,提出了预测超临界态流体通过音速喷管流量的新方法并得到了实验验证.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

采用固相微萃取(SPME)高效液相色谱法(HPLC)同时测定了水中苯酚、4-硝基酚、3-甲基酚、2,4-二氯酚、2,4,6-三氯酚、五氯酚等六种酚类化合物的含量.采用ZORBOX SB-C18柱,以甲醇-1%乙酸水溶液为流动相进行梯度洗脱,流速为1.0 mL/min.紫外检测波长为254、280 nm.六种酚类化合物的检出限为0.31~1.90μg/L,加标回收率为88%~103%.该方法操作简单,能快速、准确地检测水中的酚类化合物.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

用高效液相色谱 (HPLC)法研究了武汉东湖周年及围隔实验水柱颗粒物色素的组成及变化。共检测到约 2 0种色素 ,类胡萝卜素含量较高的有硅藻的标志色素岩藻黄素 ,隐藻的异黄素 ,蓝、绿藻的黄体素、玉米黄素及胡萝卜素。东湖叶绿素a的代谢产物主要为脱植基叶绿素a(全湖年均约占叶绿素a的 5 % ) ,而非脱镁叶绿素a或脱镁叶绿酸a。围隔实验结果表明 :叶绿素a与总浮游植物 (r =0 .84) ,叶绿素b与绿藻 (r=0 .77) ,岩藻黄素与硅藻 (r =0 6 8) ,异黄素与隐藻生物量 (r=0 .83

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The antibacterial drug furazolidone belonging to the group of nitrofuran antibacterial agents has been widely used as an antibacterial and antiprotozoal feed additive for poultry, cattle, and farmed fish in China. During application a large proportion of the administered drug may reach the environment directly or via feces. Although the use of furazolidone is prohibited in numerous countries, there are indications of its illegal use. It is known that furazolidone can be rapidly metabolized to 3-amino-2-oxazolidinone (AOZ) in the body of the target organism. In this study, a total of 21 fish feed samples, including 17 commercial fish feeds from local markets in China (representing 15 different formulations) and 4 fish feeds obtained from Germany and Turkey, respectively, are analyzed to determine whether the drug is still illegally used or commercially available feeds are contaminated by this drug. High-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods have been implemented to determine furazolidone and its metabolite AOZ in fish feeds containing animal protein, respectively. An efficient and convenient cleanup method for the determination of furazolidone in fish feeds is developed, and a simple cleanup method for the determination of AOZ is used. Method recoveries for samples used were determined as 87.7-98.3% for furazolidone at two spike levels of 2.0 and 5.0 ng g(-1) and as 95.6-102.8% for AOZ at spike levels of 0.4 and 0.8 ng g(-1). Limits of detections were 0.4 ng g(-1) for furazolidone and 0.05 ng g(-1) for AOZ. The established methods are therefore suitable for the determination of furazolidone and its metabolite AOZ in fish feeds at trace contamination levels. Using the established methods, all fish feed samples have been proved to be furazolidone negative; however, AOZ is tested in 16 of 17 fish feeds obtained from local markets in the Hubei province of China, with a positive rate as high as 94.1%.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

手性是自然界的一种普遍现象,生命现象离不开手性。手性物质在有机化学、药物化学、生物化学以及功能材料等领域显示出诱人的应用前景。外消旋体的拆分是手性研究的重要基础工作。高效液相色谱手性固定相法(HPLC-CSP)在对映体化合物的分离分析和制备方面表现出独特的优势。本论文以旋光性联萘类聚合物和纤维素类衍生物涂敷的手性固定相进行分析级和半制备级色谱拆分,研究和探讨了它们对外消旋化合物的手性识别能力。1. 纤维素类聚合物的合成 将微晶纤维素与相应的酰氯或异氰酸酯反应获得四种纤维系类衍生物,纤维素三苯甲酸酯(CTB)、纤维素三苯基氨基甲酸酯(CTPC)、纤维素三(3,5-二甲基苯基氨基甲酸酯)(CDMPC)、纤维素三联萘甲酸酯(CTBPT)。红外、核磁、元素分析证明原料纤维素已酯化完全。2. 旋光性聚合物手性固定相及HPLC手性柱的制备采用聚合物涂敷硅胶方法制备了四种纤维素类、三种联萘聚酰胺手性固定相和二种半制备级纤维素手性固定相,匀浆法装柱。研究了不同的涂敷液对色谱柱效的影响。3. 旋光性联萘聚酰胺手性柱拆分能力的探讨 在三种由(S)-联萘聚酰胺涂敷的色谱柱上,以多种流动相体系对多种外消旋化合物进行手性折分试验。4. 纤维素类手性分析柱拆分能力的研究 对手性柱进行塔板数和稳定性测试及拆分能力研究。对一些外消旋化合物实现了手性拆分。由实验结果可以看出,以CDMPC涂敷的手性柱对多种外消旋化合(包括药物)具有手性拆分能力,具分离度较高。5. 半制备级拆分 对三种外消旋药物在纤维素半制备色谱柱上进行了半制备级拆分。我们在分析型色谱柱进行了流动相条件的选择,将优化后的分析条件直接放大到半制备色谱中,不仅节省了模索条件的时间,而且可以节省大量的流动相,预计一天内所能达到的对外消旋体最大拆分量可达克级以上。6. 进行了HPLC-UV-旋光仪的联用检测研究,实现了在线流动过程中旋光曲线的绘制。