RPLC分离果酸的研究

本文用反相高压液相色谱(RHLC)研究了果酸的分离,找到了用紫外与示差折光检测器同时检测分离果酸的最佳条件,并以0.01M(NH_4)_2HPO_4 用H_3PO_4调节PH2.2～2.5。在上述条件下使果酸得到分离,用保留时间定性,用标准酸样的直线方程来定量。并对果实橙子中的柠檬酸和健力宝饮料中的酒石酸作了定量。     

应用色谱/质谱联用方法分析霉菌单加氧酶羟基化齐墩果酸体系

用反相高效液相色谱法/质谱法对天然药物齐墩果酸及其以霉菌的P450酶系作为生物催化剂的齐墩果酸羟化体系中齐墩果酸和羟化齐墩果酸进行分离分析.方法选用Lichrospher C18柱,以乙腈-水为流动相,进行梯度洗脱,用二极管阵列检测器(DAD)和电喷雾质谱(ESI-MS)为检测手段,通过色谱图和对应质谱图,确定了齐墩果酸及其羟化产物的色谱行为,建立了HPLC/DAD/ESI-MS联用法分离鉴定齐墩果酸及羟化产物的快速有效的方法.     

反相高效液相色谱法测定七种中药中齐墩果酸

首次用反相高效液相色谱法分离并测定了地肤子、连翘、牛膝、泽兰、白花蛇舌草、夏枯草、柿蒂七种中药中的齐墩果酸。建立了中药中齐墩果酸分离、测定的色谱方法。色谱条件：ＯＤＳ柱，甲醇＋水（９０＋１０）为流动相，紫外检测器检测波长２０７ｎｍ。本研究为扩大中药及植物中齐墩果酸药物资源的开发提供了简便、灵敏、准确的分离测定方法。     

毛细管电泳分离山茱萸中的熊果酸和齐墩果酸

中药山茱萸是山茱萸科植物去种子的成熟果实[1],对心血管、免疫系统等有活性作用,具有补益肝肾和涩精固脱的功效,主治眩晕耳鸣,腰膝酸痛,阳痿遗精,遗尿尿频,崩漏带下,大汗虚脱,内热消渴等.对山茱萸研究较多的是药理药效作用,对主要成分的分离分析尚报道不多,其中,对山茱萸中的熊果酸和齐墩果酸的分析有薄层扫描法[2,3],但其有效成分分析也没有统一的方法和质量标准.本文用高效毛细管电泳对山茱萸中的熊果酸和齐墩果酸进行分离分析,为中药现代化和制定质量标准提供参考依据.     

圆萼刺参中的芦丁,熊果酸和齐墩果酸的定性定量分析

采用薄层色谱法(TLC)和反相高效液相色谱法(RP-HPLC)对藏药材圆萼刺参中的芦丁,熊果酸和齐墩果酸进行定性和定量的分析。定性分析:TLC法检定芦丁和熊果酸和齐墩果酸成分,薄层色谱条件是以V(乙酸乙酯)∶V(丁酮)∶V(甲酸)∶V(水)=10∶6∶1∶2为展开剂,喷以10 g/L NaNO2的1%甲醇溶液在105℃检定芦丁,以V(CHCl3)∶V(乙酸乙酯)=1∶1为展开剂,喷以V(H2SO4)∶V(甲醇)=1∶2溶液在105℃检定熊果酸和齐墩果酸。定量分析:RP-HPLC法测定圆萼刺参中芦丁,流动相:V(甲醇)∶V(0.4%H3PO4溶液)=38∶62;检测波长340 nm;RP-HPLC法测定熊果酸和齐墩果酸,流动相:V(甲醇)∶V(0.2%H3PO4)溶液=85∶15;检测波长215 nm;圆萼刺参中的齐墩果酸,在本种植物中首次发现。     

熊果酸与齐墩果酸高效液相色谱分离条件优化

描述了熊果酸、齐墩果酸色谱保留行为与流动相pH和有机溶剂体积分数之间的函数关系,并求解了各自模型中的9个参数,得到在流动相中熊果酸的电离常数pKa=4.8145,齐墩果酸电离常数pKa=4.9317。文章还对模型外推过程中存在的误差进行了校正,并运用校正后的模型预测熊果酸的容量因子,实验值接近预测值,误差小于5%。最后采用熊果酸和齐墩果酸的容量因子与流动相pH和有机溶剂组成之间的函数关系,进行了两者在同一流动相中分离条件的优化,获得了最佳的分离条件:流动相中甲醇体积分数为85.2%,pH为6.50。     

应用C_(30)色谱柱高效液相色谱法同时分析枇杷叶中三萜酸类同分异构体

建立了一种快速、简便测定中药枇杷叶中4种三萜酸成分的液相色谱分析方法。枇杷叶经甲醇提取并定容后,采用C30色谱柱进行分离,以乙腈-水(95∶5,v/v)为流动相进行洗脱,流速为1.0 mL/min,于210 nm波长下检测。对不同产地枇杷叶中的山楂酸、科罗索酸、齐墩果酸和熊果酸4种同分异构体进行了测定和比较。结果表明,该方法分离度好(分离度(R)≥2.2),精密度高(RSD≤1.1%),线性关系良好(r≥0.999 2),重现性良好(RSD≤4.4%),加标回收率范围为95.4%~101.7%(RSD≤4.8%),满足定量要求。该方法简便、快速,结果可靠,可作为枇杷叶质量评价的方法。     

中药竹节香附化学成分的研究(Ⅰ)

从中药竹节香附根茎中分离出八个化合物。经光谱分析和化学方法鉴定:化合物1为薯蓣皂甙元(Diosgenin),化合物2为齐墩果酸(Oleanolic acid),R₀为齐墩果酸-3-O-α-L-哌喃阿拉伯糖甙。本文仅报导这三个化合物的分离与鉴定。     

无机硫氧化合物的分析化学

介绍滴定分析和仪器分析对无机硫氧化合物水溶液的定量分离分析。滴定分析一般只能定量S^2-,S^2-2,SO^2-3,S2O^2-4,S2O^2-3,SxO^2-6等离子中的一种或多种的总量,仪器分析则对多种离子混合物的分离和定量非常有效。     

硫酸钴中痕量铅及铅的原子吸收光谱测定

提出了用磷酸钇(YPO4)作为共沉淀捕集剂分离富集硫酸钴溶液中的痕量铅，用火焰原子吸收光谱测定铅的方法。共沉淀受pH、YCl3和H3P4溶液用量的影响。结果表明，在pH为3．0～4．0时，YPO4能够定量共沉淀硫酸钴溶液中的铅。铅的加标回收率为96．4％，排除了基体干扰，取得了较为满意的结果。     

Estimation of metal impurities in high-purity nitric acids used for metal analysis by inductively coupled plasma-mass spectrometry.

A simple method to estimate the amounts of ultra-trace metal impurities in nitric acid reagents has been developed. The determination of sixty-four metals in nitric acid was accomplished by direct measurements of 0.1 M nitric acids accurately diluted with ultrapure water by ICP-MS. Though accurate metal concentration could not be obtained for all of the elements, we could effectively evaluate the nitric acid quality by comparing the ion counts of the samples, ultrapure water and standard metal solutions for a calibration prepared with Ultrapur nitric acid.     

Self-assembled monolayers of alkanoic acids on the native oxide surface of SS316L by solution deposition

Stainless steel 316L is a widely used biomaterial substrate whose biocompatibility could be improved by surface modification. As a first step in this process, self-assembled monolayers of octanoic acid, octadecylcarboxylic acid, 16-hydroxyhexadecanoic acid, 12-aminododecanoic acid, and 1,12-dodecane dicarboxylic acid have been formed on the native oxide surface of stainless steel 316L by a simple, one-step solution deposition method. The ordering, close-packing, and coverage of the monolayers formed were characterized by diffuse reflectance infrared spectroscopy, contact angle measurements, and atomic force microscopy. The same procedure was applicable for all long alkyl chain carboxylic acids. This process formed chemically and mechanically stable monolayers. These carboxylic acids formed a bidentate bond with the stainless steel substrate. Robust chemical attachment of the acids to stainless steel through a simple process provides a stepping stone to improving the biocompatibility of stainless steel 316L.     

High‐speed separation and detection of amino acids in laver using a short capillary electrophoresis system

A high‐speed separation method of capillary MEKC with LIF detection had been developed for separation and determination of amino acids in laver. The CE system comprised a manual slotted‐vial array (SVA) for sample introduction that could improve the separation efficiency by reducing injection volume. Using a capillary with 80 mm effective separation length, the separation conditions for amino acids were optimized. Applied with the separation electric field strength of 300 V/cm, the ten amino acids could be completely separated within 2.5 min with 10 mol/L Na₂HPO₄–NaOH buffer (pH = 11.5) including 30 mmol/L SDS. Theoretical plates for amino acids ranged from 72 000 to 40 000 (corresponding to 1.1–2.0 μm plate heights) and the detection limits were between 25 and 80 nmol/L. Finally, this method was applied to analyze the composition of amino acids in laver and eight known amino acids could be found in the sample. The contents of five amino acids, tyrosine, glutamic acid, glycine, lysine, and aspartic acid that could be completely separated in real sample were determined. The recoveries ranged from 82.3% to 123% that indicated the good reliability for this method in laver sample analysis.     

Qualitative and quantitative analysis of phenolic acid glycosides in Ginkgo biloba L. leaf,G. biloba leaf extract and its injection

Ginkgo biloba L. leaf (GBL) is one of the most commonly used medicinal plants in the world. Phenolic acids with biological activities have a relatively high content in G. biloba leaf extracts (GBE); therefore they are of great significance for the quality control of GBL, GBE and its preparations. However, there have been few studies focused on their analysis. In this work, 12 phenolic acids, including 11 phenolic acid glycosides, were identified by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC–Q-TOF/MS). Then, a method combining enzymolysis with HPLC was established for quantification of phenolic acid glycosides. It was found that the aglycones of phenolic acid glycosides mainly comprised five phenolic acids: 2,4,6-trihydroxybenzoic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid and p-coumaric acid. The quantitative method was validated, and the correlation coefficient (0.9993–0.9999), recovery (≥88.4%), repeatability (≤0.8%), and inter-day precision (≤5.5%) were satisfactory. Finally, the contents of glycosides of five phenolic acids in GBL, GBE and GBE injection from different sources were determined by the developed method. The method was accurate, repeatable and practicable, which could be helpful for the quantification of phenolic acid glycosides in other products containing GBL or GBE.     

Fast analysis by gas-liquid chromatography. Perspective on the resolution of complex fatty acid compositions

Separation of fatty acids as methyl ester (FAME) derivatives has been carried out using short and highly polar capillary column developed for fast gas-liquid chromatography (GLC) applications. The GLC parameters have been optimized in order to achieve separation of FAME ranging from 4:0 (butyric acid) to 24:1 in less than 5 min. Milk fat that has by far the most complex fatty acid composition among edible fats and oils has been used to optimize the method. The volume of the oven has been reduced in order to allow for a heating rate of 120 degrees C/min and to rapidly cool-down to the initial temperature (50 degrees C) of the GLC program. The GLC conditions developed are not suitable to achieve separation of positional and geometrical isomers of octadecenoic acid but are useful to perform separation of major fatty acids in milk fat. The conditions developed could be used to analyze edible fats and oils or biological samples such as plasma or red blood cell lipids. The results confirmed that short and highly polar fast columns operating under optimal conditions could be used to separate the fatty acids in various matrices.     

淋洗液自动发生-离子色谱法同时测定食品中的21种有机酸

建立了一种利用离子色谱法同时测定样品中奎尼酸、乙酸、丙酮酸、草酰乙酸、甘露酸、乳酸、琥珀酸、苹果酸、酒石酸、草酸、富马酸、抗坏血酸、α-酮戊二酸、肉桂酸、水杨酸、柠檬酸、异柠檬酸、阿魏酸、顺乌头酸、反乌头酸、β-香豆酸等21种有机酸的方法。样品经提取、脱色、过滤后用IonPac AS11分离柱分离,以EG40自动淋洗液发生器生成的5~34 mmol/L KOH为淋洗液洗脱,抑制电导检测器检测。21种有机酸的浓度与其峰面积在一定的范围内呈良好的线性关系,检出限均低于0.188 mg/L,加标回收率为91.5%~101.8%。该法用于多种食物样品中有机酸的测定,结果令人满意。     

Simultaneous quantitation of Krebs cycle and related acids by mass fragmentography

Methods are described for simultaneous quantitation of Krebs cycle and related acids by gas chromatography--mass spectrometry using deuterium-labelled acids and n-butyl-d9-esters of the organic acids as internal standards. Using sulphuric acid as esterification catalyst, only lactic, succinic, fumaric, malic, maleic and citric acids were found to be stable to hydrogen exchange and could be used as reference standards in the deuterated form. In contrast, pyruvic, oxalacetic, alpha-ketoglutaric and malonic acids were found to exchange their deuterium readily and could not be employed for this purpose. All the acids could be quantitated using n-butyl-d9-esters of reference organic acids as internal standards, following a separate preparation of the n-butyl derivatives of the unknown acids. The method is suitable for routine analysis of organic acids at the picogram level in perchloric acid extracts of tissues.     

Highly sensitive biotin-labelled hybridization probe

A simple chemical method for introducing biotin into nucleic acids has been developed for the synthesis of nonisotopic hybridization probes. The method is based on the reaction of biotin hydrazide with amino residues of nucleic acids by using glutaraldehyde as a bifunctional coupling reagent. Biotin-labelled deoxyribonucleic acid (DNA) was detected by the use of alkaline phosphatase-labelled avidin, and alkaline phosphatase activity was measured by colorimetric and chemiluminescence methods. The chemiluminescence method using the nicotinamide adenine dinucleotide phosphate (NADP)/alcohol/alcohol dehydrogenase/microperoxidase/isoluminol system gave the highest sensitivity. A few picograms of lambda-phage DNA coated on a microtiter plate well could be detected by this method.     

High-performance liquid chromatography-thermospray mass spectrometry of hydroperoxy polyunsaturated fatty acid acetyl derivatives.

A method for the analysis of hydroperoxy polyunsaturated fatty acids was developed. The hydroperoxy groups were acetylated by acetic anhydride, and the mixture was partially purified on a Sep-Pak C18 cartridge and analysed by high-performance liquid chromatography with thermospray mass spectrometry. Generally, the base ion, [M+H - n(60)]+ or [M+H - n(60) - n(H2O)]+, is produced through elimination of acetic acid or water (n = number of hydroperoxy groups). The detection limit for these derivatives was ca. 1 pmol at concentrations of hydroperoxy polyenoic acids prior to derivatization. Using this method, many hydroxy and hydroperoxy polyunsaturated fatty acid derivatives could be detected simultaneously within 30 min on a selected-ion monitoring detection chromatogram without a gradient system. The assay was successfully applied to hydroxy and hydroperoxy polyunsaturated fatty acids from an incubation mixture of rat brain homogenate to which polyunsaturated fatty acids had been added.     

Carboxylic Acids as Traceless Directing Groups for the Rhodium(III)‐Catalyzed Decarboxylative CH Arylation of Thiophenes

A rhodium(III)‐catalyzed carboxylic acid directed decarboxylative C? H/C? H cross‐coupling of carboxylic acids with thiophenes has been developed. With a slight adjustment of the reaction conditions based on the nature of the substrates, aryl carboxylic acids with a variety of substituents could serve as suitable coupling partners, and a broad variety of functional groups were tolerated. This method provides straightforward access to biaryl scaffolds with diverse substitution patterns, many of which have conventionally been synthesized through lengthy synthetic sequences. An illustrative example is the one‐step gram‐scale synthesis of a biologically active 3,5‐substituted 2‐arylthiophene by way of the current method.