高温液相色谱的原理及研究进展

高温液相色谱是色谱发展的一个新领域。温度升高,流动相的粘度降低,分析物的扩散速度加快,则溶质及溶剂的传质阻力降低,可实现在较高的流速下分离,同时系统的压力会随着温度的升高而降低。升高色谱柱的温度,不仅可以加快分析速度,而且还可以改善峰形,减少有机溶剂的使用。在此基础上发展出的亚临界水色谱,更符合绿色色谱的要求,同时扩大了液相色谱的应用范围。本文综述了高温条件下,温度对柱效、保留值、选择性、溶剂洗脱特征及色谱柱稳定性的影响,介绍了高温色谱的应用进展。     

膜色谱技术在生物大分子分离与纯化中的应用

膜色谱是将液相色谱与膜分离融合于一起的新型生化分离技术,具有选择性高、分离速度快、能耗低、易放大等特点,在生物大分子的分离与纯化方面有广阔的应用前景。本文论述了膜色谱的种类、制备方法及作用机理,并介绍了亲和、疏水、离子交换、多级等四种膜色谱在近五年来的应用进展。     

高效液相色谱仪常见故障分析及解决方法

高效液相色谱是一种具有高灵敏度、高选择性的高效快速分离、分析技术。它既能用于微量组分的分析测定．又能用于大量的制备分离，灵活多样，应用范围已超过其他各种分离方法。液相色谱仪主要由贮液瓶、输液泵、进样器、色谱柱（包括柱温箱）、检测器和数据记录及处理装置组成。高效液相色谱仪在使用过程中常会出现一些影响分析结果的问题，     

高效液相色谱荧光法测定土壤中16种多环芳烃

本文介绍了采用高效液相色谱、荧光检测器测定土壤中16种多环芳烃。通过对液相色谱柱的选择、色谱条件、荧光激发和发射波长等条件的优化,实现16种多环芳烃完全分离。特别是对16种多环芳烃的激发和发射波长进行选择,进一步提高检测灵敏度、选择性,降低了干扰。在优化的实验条件下,荧光检测器的检出限为0.09～1.57ng/mL,样品加标回收率为86%-108%。     

NPLC×RPLC二维液相色谱系统分离分析牛黄解毒片提取物成分的实验研究

构建了定量环-阀切换接口的二维液相色谱系统(NPLC×RPLC),采用此系统对牛黄解毒片样品进行分离分析,以4.6mm×50 mm i. d.的SiO_2正相色谱柱为第一维,4.6mm×250 mm i. d.的C18反相色谱柱为第二维。根据有机溶剂的特征,在第一维正相色谱流动相中加入1,4—二氧六环;第二维反相色谱流动相中加入异丙醇,同时通过升高第二维色谱温度的方法增加两维流动相间互溶性,在改善流动相兼容性的同时,有效调整分离选择性。最终,通过总共440min的七次切割共检测出了153个峰,达到950的峰容量。     

高效液相色谱分析磷脂研究进展

天然磷脂是含磷酸的类脂化合物，广泛存在于自然界中，在工业生产、食品科学、医药学、生命科学等研究方面都有重要的作用。磷脂的研究手段多样，高效液相色谱在磷脂的分离、检测方面具有优势。结合近年来国内外对高效液相色谱分离磷脂的研究报道，分析了液相色谱分离磷脂所用固定相、流动相、检测器等关键因素，认为液相色谱与质谱联用是未来液相色谱分析磷脂的技术方向。     

磷脂的高效液相色谱分析

天然磷脂是含磷酸的类脂化合物,广泛存在于植物、动物及微生物体中,在工业生产、食品科学、医药学、生命科学等研究方面都有重要的应用。磷脂的研究手段多样,高效液相色谱在磷脂的分离、检测方面具有优势。本文结合近年来国内外高效液相色谱分离磷脂的研究报道,对高效液相色谱分离、检测磷脂的方法进行了分类、评价。     

高效液相色谱层析在环境分析中的应用研究

随着环境污染程度的加重与污染环境的化学物质种类的增多，如何在分析中快速准确的鉴定出污染物种类与性质是当前环境研究中面临的一大难题。高效液相色谱层析是一种结合了经典液相色谱法和气相色谱法的分离特点并在高科技水平基础上发展起来的一种新型分离方法。由于高效液相色谱层析法分离能力高，分离速度快，应用范围广．所以在化学，生物等方面快速、广泛的应用开来。本文对高效液相色谱层析法进行了简单介绍，重点分析了该方法在环境分析领域的应用，期望对环境分析起到指导作用。     

分子印迹填充色谱柱用于药物分离的研究进展

分子印迹聚合物(MIP)是由模板分子与功能单体相互作用,然后在合适的条件下加入交联剂聚合而成的一种高分子材料.将该聚合物装填高效液相色谱(HPLC)固定相,可利用其印迹空穴中的特异性识别位点,实现模板分子和竞争分子间的分离.综述了近年来分子印迹填充色谱柱的发展状况、合成方法与袁征手段.重点论述对分子印迹填充色谱柱分离效果和印迹效果产生影响的重要因素,指出模板分子的选择、填料的表面结构以及色谱条件对分离有较大影响.最后,对分子印迹色谱柱在药物分离领域的发展前景进行展望,提出了不足之处.     

六氟化硫(SF6)标准气体GC-μECD分析方法的研究

讨论了氮、空气中SF6 GC-μECD的分析方法,对影响色谱分离条件的动力学因素(操作变量)进行了选择性的研究;方法具有高的灵敏度和好的选择性,检测限可达到20×10-12mol/mol,相对标准偏差＜1%.     

Identification of organic solvents by a virtual multisensor system with hierarchical classification

To improve the selectivity of semiconductor gas sensors, temperature modulation is often used. We present a study showing the potential of this technique with information gained comparable to multisensor systems. A dynamic operating mode coupled with a low-complexity evaluation strategy allows the identification of six organic solvent vapors over a wide concentration range (2-200 ppm) with a single sensor, for example, for leak detection systems. The system features low false alarm rates; in addition, interference by other gases, such as CO or NO/sub 2/, can be suppressed. For even higher identification power, switching on-line between different temperature cycles was studied, which provides better information for critical decisions.     

微波条件下聚丙烯塑料中抗氧化剂的迁移研究

借助液相色谱分析技术,研究了微波条件下食品接触材料聚丙烯(PP)中 4 种抗氧化剂向食用玉米油的迁移。 实验表明,微波加热功率和时间共同影响抗氧化剂在食用玉米油中的迁移,4 种抗氧化剂的迁移量随着微波加热时间和加热功率的增加而增大。 最后根据迁移数据给出了微波加热时间及功率与迁移量之间的关系。     

正庚烷/有机硫体系渗透汽化脱硫

以正庚烷/有机硫体系模拟汽油体系,用硅橡胶(PDMS)复合膜进行渗透汽化脱硫性能研究,并考察料液温度、料液含硫量对膜分离渗透性能的影响.实验表明,温度对膜分离渗透性能有较大影响,而料液含硫量对分离渗透性能的影响可以忽略.结合实验结果,用基团贡献法分析了该复合膜对不同种类有机硫的选择性.实验数据与理论分析吻合,PDMS复合膜对不同有机硫的选择性顺序为:噻吩>2-甲基噻吩>2,5-二甲基噻吩>正丁硫醇>正丁硫醚.     

高效液相色谱输液泵流量脉动的研究

设计并搭建了输液泵输出流量脉动测试装置,在不同测试条件下,研究了高效液相色谱系统中常用的串联式和并联式往复柱塞泵的流量脉动。实验得到了这2种输液泵流量脉动率随流量或背压的变化趋势,并证实输液泵的流量脉动周期与凸轮运动周期接近。利用脉动阻尼器来降低流量脉动,可使2种输液泵在6.5 MPa背压下的流量脉动率降为原来的10%左右。该测试装置及方法可在高效液相色谱输液泵的设计改进过程中提供帮助。     

Affinitive separation and on-line identification of antitumor components from Peganum nigellastrum by coupling a chromatographic column of target analogue imprinted polymer with mass spectrometry

A coupled LC-MS (liquid-phase chromatography and mass spectrometry) system consisting of a combination of a column of molecularly imprinted polymer (MIP) and a MS detector was used for affinitive separation and on-line identification of the antitumor components, harmine and harmaline, from the methanol extract of Peganum nigellastrum seeds. Three molecularly imprinted polymers were synthesized with porogens bearing different hydrogen bonding capacities with harman, the structural analogue of harmaline, and harmine as the template. The affinity and selectivity of the anti-harman MIPs for the targets, harmine and harmaline, were investigated chromatographically, and the influences of the porogens and sample loads on the retention of the target compounds were also discussed. In addition, the target binding capacities of the MIPs were evaluated by frontal chromatography. When the MIPs were further used in a LC-MS system to separate the extract of herb, it was observed that imprinting with different porogens would cause the MIPs to exhibit different tendencies to adsorb the matrix components from the herb. Though the MIP prepared with a porogen of less hydrogen bonding capacity possessed higher selectivity and stronger affinity for the targets, matrix components in the herb extract interfered with the chromatographic performance more seriously when it was used as the LC solid phase in the LC-MS system for selective extraction of harmaline and harmine from the crude herb extract. Positively, the MIPs were stable and reproducible in the separation test, and the imprinting columns could efficiently separate the antitumor components from the herb extract after the sample was simply pretreated. The work in this paper would be helpful for the further extraction and identification of certain pharmacophoric compounds in herbs by a LC-MS system using MIPs as the HPLC solid phase.     

Methylene Selectivity and Eluotropic Strength Variations in Subcritical Fluid Chromatography with Packed Columns and CO(2)-Modifier Mobile Phases

This work has consisted of better understanding the chro-matographic behavior in subcritical fluid chromatography with CO(2)-acetonitrile and CO(2)-methanol mobile phases. To that end, the changes of solute solubility in the mobile phase have been studied by determination of methylene selectivity of a homologous series. Moreover, eluotropic strengths have been calculated for mobile phases containing from 5 to 45% modifier. To carry out the studies in all ranges of the subcritical area, experimental designs have been used. The influences of analytical temperature (from 10 to 30 °C) and outlet pressure (from 10 to 20 MPa) have also been investigated both on solubility and on eluotropic strength. A more general comparison of elu-otropic strengths of subFC and HPLC has been achieved.     

不同粒度β沸石的催化性能

采用不同粒度的β沸石为关键组分制备成催化剂,以正庚烷为原料,在连续流动固定床微型反应器上进行加氢裂化性能评价,结果表明,在相同反应温度下,β沸石粒度减小,转化率明显提高,异构选择性降低,但相同转化率下的异构选择性基本相当。     

Desorption and pervaporation properties of zeolite-filled Poly(dimethylsiloxane) membranes

The role played by zeolite fillers in PDMS membranes was studied by desorption and pervaporation. The data on the desorption of different solvents from the membranes made of poly(dimethylsiloxane) (PDMS) filled with silica and different zeolites show that the solvent molecules are extracted in two stages. The first stage, which occurs at a low temperature (ca.50 °C), would correspond to the extraction of the solvent molecules in the ’bulk-like state’ in PDMS, while the last stage, at high temperature, would correspond to the extraction of the solvent molecules in the ’bound state’. There is a clear contribution of the zeolites to the membrane performances in pervaporation, even at a low zeolite content in PDMS (ca. 20 wt. %). The hydrophobic zeolites enhance significantly the organic flux, leading to an improvement of both the flux and the selectivity of PDMS. The ZSM-5 zeolite imparts to PDMS a higher selectivity but lower flux compared with SY-2 zeolite. The silica filler exhibits a crosslinking effect on PDMS, i.e. a slightly higher selectivity and lower flux than the pure PDMS membrane. Received: 11 June 2001 / Accepted: 11 June 2001     

Influence of water on the solubility of two steroid drugs in hydrofluoroalkane (HFA) propellants

The objective of this research work was to investigate the influence of water level, temperature, and propellant composition on the solubility of two hydrophobic steroid drugs, triamcinolone acetonide (TAA) and beclomethasone diapropionate (BDP). pMDIs containing TAA or BDP, spiked water, and propellant blend with different ratios of HFA 134a and HFA 227 were prepared. The contents of the prepared pMDIs were filtered through a 0.22 mm Acrodisc, syringe filter into a receiving canister after the pMDIs were equilibrated at 15°C, 25°C, 30°C, and 40°C. The drug concentration in the receiving canisters was determined by HPLC and the drug solubility in the propellant blend was calculated. Also, the drug crystal collected on the filter from the donor pMDIs were characterized by x-ray diffraction. The solubility of TAA and BDP varied with propellant composition at all experimental temperatures investigated. The solubility of TAA and BDP increased as the temperature was increased at all propellant compositions and water levels studied, but decreased as the water level in the propellant system was increased at all compositions and temperatures. The x-ray diffraction results indicated that the water in the propellant system had no significant influence on the crystal characteristics of TAA in HFA propellant system, but had a significant impact on the crystal characteristics of BDP was higher than TAA at all propellant compositions, experimental temperatures and water levels investigated. The solubility of TAA and BDP was not only influenced by propellant composition and storage temperature, but also depended on the water level in the propellant system. As a consequence, the crystallinity of the drugs formulated in HFA propellant was influenced by the temperature, propellant composition and the water level in the propellant system. The impact of these factors on the crystallinity of formulated drugs.     

On-line solid-phase extraction of triazine herbicides using a molecularly imprinted polymer for selective sample enrichment

A coupled-column system, consisting of a combination of a molecularly imprinted polymer (MIP) and a C(18)-silica column, was used for selective triazine detection in the HPLC mode. Complex aqueous samples, spiked with triazines, were selectively extracted by the MIP followed by subsequent identification by analytical reversed-phase chromatography. The MIP showed good performance for selectively discriminating triazines from humic acid, whereas urine and apple extract had some tendency to be retained by the MIP. Enrichment was observed in all cases, and triazine-enrichment factors of up to 100 could be recorded, with good extraction efficiency (74-77%). The results indicate that the high selectivity of MIPs can be favorably used for selective sample enrichment in conjunction with reversed-phase HPLC.