Resolution of Polynuclear Aromatic Hydrocarbons by Packed Column GLC

Abstract

Specific GLC stationary phases have been identified which allow the resolution of certain polynuclear aromatic hydrocarbon (PAH) isomers with packed six foot columns. Phenanthrene and benz(a)anthracene can be measured in the PAH fraction of tobacco smoke condensate without significant interferences from anthracene and chrysene, respectively.     

不锈钢宽口径填充毛细管液相色谱柱

 设计了一种零死体积的二通式柱尾结构和一种使匀浆填料均匀进入色谱柱管内的储料池 ,研究了制备内径在 0 5mm～ 1 0mm的不锈钢宽口径填充毛细管液相色谱柱的方法。详述了以不同牌号、规格的反相ODS类固定相制备的不同柱长的色谱柱的性能。通过折合板高 /折合流速关系和不对称因子对柱性能进行了评价 ,结果表明 ,该方法制备的色谱柱柱效达到理论值的 75 %以上、RSD为 6% ,稳定性也很好。将其应用于抗癫痫药物和氯苯类化合物的分析 ,结果令人满意。     

宽口径填充毛细管液相色谱柱柱尾结构的改进

 设计并评价了尾锥形填充毛细管液相色谱柱,与粘结型柱尾比较,前者柱效高且van Deemter曲线高流速部分的流速-柱效关系明显改善。在折合流速为10～15时,前者的柱效比后者高出30%～50%。谱带的抛物线状的流形在尾锥形柱内得到改善,使色谱峰的对称性有明显提高。比较了两种结构的色谱柱在芳烃快速分析中的分离效果,结果是尾锥形柱的分离性能优于粘结型柱。     

Influence of Column Material on Efficiency in High Speed Liquid Chromatography

Abstract

The influence of column tubular material on column efficiency in high speed liquid chromatography has been examined. For good reproducibility in HETP, the columns were first packed dry with Corasil I (28–37μ) and then heptane saturated with 3,3′-oxydipropionitrile was flown through the column. When steady state conditions were achieved, the % loading of stationary phase was 1.1%. It was found that column materials of precision bore and seamless stainless steel, aluminum, and copper gave equivalent efficiency results for retained and unretained components. Teflon coated aluminum columns were not reproducible, in regard to HETP.     

High Performance Liquid Chromatography Separations Using Short Columns Packed with Spherical and Irregular Shaped ODS Particles

Abstract

In a comparative study of the separation of a mixture of polycyclic aromatic hydrocarbrons on 5 cm and 10 cm columns packed with 3μ and 5μ ODS spherical particles, the separations achieved on the 10 cm column were not significantly better than those on the 5 cm column. Although, columns packed with 3μ ODS spherical particles gave slightly better resolution than those packed with 5μ ODS spherical particles having the same physical properties, differences were observed when columns packed with ODS spherical particles were compared with columns packed with ODS irregular shaped particles of the same size.

The results show that separations on a 5μ or 3μ packed columns takes place at the first few centimeters.     

High Performance Liquid Chromatography Separations Using Short Columns Packed with Spherical ODS Particles. II. Effect of Mobile Phase Composition on Resolution

Abstract

The effect of instrumental parameters, mobile phase composition, and flow rate on high performance liquid chromatography separations using 3 cm, 5 cm, and 10 cm columns packed with 3y spherical ODS materials is discussed. The results indicate that when instrumental parameters were optimized, the 10 cm column gave better separation than the shorter columns under the same experimental conditions. However, when the mobile phase composition was adjusted so that the solute residence time was comparable in the three columns, short and long columns gave comparable results.     

台锥形柱尾的填充毛细管液相色谱柱

首次将台锥形柱尾用于填充毛细管液相色谱柱,并与环氧胶粘的柱尾连接方式进行比较,发现在柱内径≥０．３２ｍｍ时,前者的柱效比后者高出３０％～５０％,且明显改善柱效－流速特性。对比研究了不同内径柱（０．５３ｍｍ,０．３２ｍｍ,０．２５ｍｍ）采用两种尾接方式的塔板高度与流速的关系,对产生差异的原因进行了探讨。     

High Performance Liquid Chromatography Separations Using Columns Packed with Spherical ODS Particles. III. Effect of Column Dimensions on the Resolution of a Complex Mixture

Abstract

Separations on short columns, (3 and 5 cm, packed with 3 μ ODS spherical materials) and somewhat larger ones (10 cm and 20 cm columns having 2.1 mm and 4.6 mm diameters packed with 5 μ ODS spherical materials) were compared using Aroclor 1254. With simple mixtures, the results showed that short columns can give separations comparable with those on longer columns when the percentage of the organic modifier in the mobile phase is adjusted. This was not so with more complex mixture. The results also showed that columns which have a comparable volume do not produce comparable separation. The longer column, 200 mm × 2.1 mm gave better resolution than the shorter 50 mm × 4 mm column. Also a shorter column, (100 mm × 4.6 mm), which had double the volume of a longer column. (200 mm × 2.1 mm), gave better resolution of the Aroclor 1254 test solution.     

电填充毛细管色谱柱性能的评价

报道了一种毛细管色谱柱的电填充技术,并进行了柱性能的评价研究。实验表明新的填充方法确保了色谱柱的柱效和重现性。     

黄酮醇异构体的超临界流体色谱法分离

用超临界流体色谱法进行了黄酮醇异构体的分离研究。考察了温度、压力、流动相组成、柱条件等对分离的影响。在实验的温度范围４０～６０℃和压力范围１５～３０ＭＰａ内,这组化合物都能得到很好的分离;流动相组成是影响色谱分离的最显著的因素,磷酸的加入大大改变了各物质的保留行为;考察了三种硅胶基质键合相对分离的影响,发现苯基柱用于这组异构体的分离最为合适。     

A Portable Slurry Packing Apparatus for High Performance Liquid Chromatography

Abstract

A portable apparatus for slurry packing high performance microparticulate liquid chromatographic columns is described. The packer offers lab to lab portability and ease of operations. Columns up to 50 cm in length can be accommodated with the described configuration. Material costs per column are $40 – $70, offering a substantial saving over commercially prepared columns, in situations where labor costs are minimal. Efficiencies of columns packed with this apparatus have been equivalent to or better than those obtained with commercially available columns. Columns are packed using a staged pressurization/depressurization method. This method also leads to longer column life. Evaluation of relative column efficiency is also discussed.     

气溶胶粒子通过填充柱的保留时间分布测定

采用亚微米单分散聚苯乙烯球形硬气溶胶粒子和脉冲进样技术,测定了气溶胶粒子通过无规则石英砂填充柱的保留时间分布,从保留时间分布曲线得到了气溶胶粒子在填充柱中的平均保留时间和穿透率.研究了平均保留时间和穿透率与流体流速、填充柱的长度、填料粒度和气溶胶粒子大小之间的关系.研究发现,流速越大,保留时间分布曲线越尖锐,流速越小,保留时间分布曲线越平坦;气溶胶粒子的穿透率随着柱长的增加而降低,随流速、气溶胶粒子粒径和石英砂颗粒大小的减小而减小;平均保留时间随柱长增加而增大,随流速增大而减小,随气溶胶粒子粒径减小而减小,而与石英砂颗粒大小几乎无关.     

一种多通道匀浆装填毛细管色谱柱的新装置及应用

针对目前毛细管色谱柱装柱效率低、不同批次装填的毛细管色谱柱之间性能差异大的问题,我们发展了一种多通道匀浆装填毛细管色谱柱的新装置。该装置以液相色谱泵提供压力、采用磁力搅拌保持匀浆液均匀分散,一次可装填多达6根毛细管色谱柱。以牛血清白蛋白(BSA)的胰蛋白酶酶切肽段混合物为样本,选择峰容量、蛋白覆盖率、3个特定离子的保留时间以及毛细管色谱柱柱压为指标,在毛细管液相色谱-质谱联用系统上对装填的反相毛细管色谱柱的性能进行了评价。分别考察了一次装填的6根毛细管色谱柱、两次装填的12根毛细管色谱柱以及一次装填1根与一次装填6根毛细管色谱柱的性能及稳定性。实验结果表明:同一批次装填的6根毛细管色谱柱的性能相近;不同批次装填的12根毛细管色谱柱的峰容量和覆盖率没有明显的区别,但保留时间和毛细管色谱柱柱压的稳定性较差;一次装填1根和一次装填6根毛细管色谱柱柱性能的稳定性与两次分别装填6根毛细管色谱柱的稳定性相近,即采用本装置可显著提高毛细管色谱柱的装填效率且每次装填毛细管色谱柱的数量不会对柱性能产生影响。     

Packed column supercritical fluid chromatography of isomeric polypeptide pairs

The characterization and determination of peptides is of great importance in the pharmaceutical industry as is the ability to rapidly perform targeted determinations of bioactive peptides in complex matrices. The purpose of the presented work is to assess the feasibility of packed column supercritical fluid chromatography (SFC) for the separation of two-pairs of water soluble peptides of identical mass, composition and charge that differ only in amino acid sequence. Upon evaluating a variety of conditions, trifluoroacetic acid (HTFA) in conjunction with methanol as the modifier proved to be, in general, the most successful mobile phase additive for elution of the two isomeric peptide pairs from all nitrogenous stationary phases. In contrast, water and ammonium acetate gave distorted peak shapes and therefore proved to be less satisfactory as neutral additives. The basic additive, iso-propylamine (IPAm), coupled with HA-Pyridine yielded the highest resolution factor for the complete study. Aminopropyl and HA-Pyridine columns with 5 μm particle size and 60 Å pore size were found to be best for resolution of each peptide pair. Bare silica and phenyl-hexyl stationary phases did not afford any separation. The primary roles of the carbon dioxide and methanol modifier are believed to provide (a) stationary phase solvation and (b) peptide solubility and transport; while, HTFA is postulated to fully protonate each peptide and form ion pairs between its conjugate base and cationic peptide analyte. The separation process, therefore, is best viewed as ion pair supercritical fluid chromatography (IP-SFC). For the case where IPAm gave good resolution on the HA-Pyridine column, the peptides are probably in the neutral state.     

GC with LC-like packed capillary columns

Capillary columns of 0.3–0.35 mm internal diameter and 0.3–7.7 m length, packed with 3 to 30 μm octadecylsilica stationary phases as used for liquid chromatography, were applied to gas chromatographic separation of low boiling hydrocarbons. Van Deemter plots for these columns showed the optimum column efficiency to occur at linear velocities of 4–5 cm/s. A short column was applied to the rapid separation of components of a natural gas and impurities in standard gases, while a long column was applied to the separation of complex mixtures.     

Determination of Ochratoxin A in Poultry Feed by High-Performance Liquid Chromatography with a Monolithic Column

A monolithic column with high-performance liquid chromatography coupled with an ultraviolet detector was investigated for the determination of ochratoxin A in poultry feed. A systematic study was performed using solid phase extraction with a C₁₈ cartridge for sample pretreatment with three solvent systems. Ethyl acetate:methanol:formic acid (95:5:0.5) was found to be the most suitable. Pretreated samples were injected separately into packed and monolithic columns. The effects of the mobile phases on the chromatographic figures of merits were evaluated. Better peak symmetry, improved separation, and more theoretical plates were observed using an acetonitrile:water:formic acid (99:99:2) mobile phase. The repeatability and accuracy of the method were statistically evaluated and found to be satisfactory with a limit of detection of 40 µg L^?1. The use of a monolithic column in conjunction with sample pretreatment provided good results for the determination of ochratoxin A in poultry feed.     

Amberlite XAD-4 as a Stationary Phase for Preparative Liquid Chromatography in a Radially Compressed Column

Abstract

Amberlite XAD-4, a nonpolar adsorbent with a particle size of 62 to 177 μm, was packed into 58 mm i.d. x 294 mm columns and radially compressed in the Waters Prep 500 preparative liquid chromatograph. Efficiency, loading capacity (multigram samples), resolution, recovery, and types of mobile phases were major parameters studied. Since XAD-4 is chemically inert mixed solvent and pH control from 1 to 13 can be successfully used in the mobile phase. Separations illustrating these advantages and the scope of the 58 mm i.d. column are described.     

Packed capillary column supercritical fluid chromatography of fat-soluble vitamins using liquid crystal polysiloxane coated particles

Summary Liquid crystal polysiloxane stationary phases were prepared by coating two different polymers on deactivated porous silica particles (10 m diameter, 80 Å pores). Deactivation of the silica particles before coating was necessary to prepare highly efficient and inert stationary phases for supercritical fluid chromatography (SFC). Fat-soluble vitamins E, A, K₁, K₂, D₂, and D₃ were separated on these columns using neat supercritical CO₂ as mobile phase. The analyses were completed within 40 min at 70 °C. The results were compared to those obtained using a capillary column packed with less ordered liquid crystalm,m-cyanobiphenyl-substituted polysiloxane coated particles. Reduced shape selectivity was observed with this cyanobiphenyl phase. The response factors of vitamins A, E, K₁, K₂, D₂, and D₃ when using the flame ionization detector (FID) were determined to be very similar.     

Comments on column characterization: A sulfur column

Summary The McReynolds' constants for liquid sulfur as a stationary phase in gas-liquid chromatography (GLC) are presented. A simple graphical method of pattern analysis is used to indicate the uniqueness of the sulfur column as compared with other stationary liquid phases characterized by McReynolds. The limitations of using a single factor (as polarity) for the basis for the selection of GLC columns is discussed.     

开管离子色谱柱的制备与表征

近年来,开管离子色谱(OTIC)的研究已取得重大进展,尤其是兼容OH^-淋洗液的OTIC柱的成功研制使OTIC梯度洗脱得以实现。该文介绍了各种OTIC柱的制备和表征方法,涵盖早期的二氧化硅开管柱和新近出现的有机聚合物基质开管柱,对静电乳胶附聚的OTIC柱的一系列表征方法进行了系统阐述,包括开管柱柱容量的实验测定和理论计算方法、固定相相同时填充柱与开管柱之间的联系、柱效改善方法以及开管柱均一性表征等。