Packing Materials For Liquid Chromatography Research Articles

Preparation and evaluation of magnesia-coated silica as column packing material for high-performance liquid chromatography

The preparation of a mixed oxide gel composed of silica and magnesia was attempted by a coating method in order to develop a useful column packing material for liquid chromatography. The physical properties of the gels obtained remained almost the same as those of the native silica gel, but the surface silanol groups and the acid strength both changed, depending on the preparation conditions. The chromatographic behaviour of the gels was tested using benzene, dimethyl phthalate, pyridine and phenol as solutes. The magnesia-coated silicas calcined at temperatures between 600 and 800°C exhibited the excellent separation abilities for these compounds.

Liquid Chromatographie separation of polycyclic aromatic hydrocarbons with cerium(IV) oxide as packing material

Cerium oxide (CeO 2) was evaluated as a column packing material for liquid chromatography. A pretreated CeO 2 slurry was made in ethylene glycol and was forced into a stainless steel tube (125 × 4.6 mm) for 60 min at a constant pressure of ca. 550 kg/cm 2. Naphthalene, anthracene, pyrene and chrysene were successfully separated using pure n-hexane as a mobile phase. The column efficiency is approximately 500 theoretical plates. The separation efficiency of the CeO 2 column was compared with a commercial silica gel column. The main advantage of the CeO 2 column was its improved separation efficiency for phenanthrene and pyrene.

Immobilization of glucosidase onto silica-based, amino functionalized beads for enzymatic hydrolysis of urinary phenol prior to liquid chromatographic analysis

An amino-functionalized silica commercial liquid chromatography packing material was used instead of controlled-pore glass as the support to react with glutaraldehyde and then to directly immobilize the β-glucosidase. After enzymatic hydrolysis, the urinary phenol was separated by reversed-phase liquid chromatography and monitored by an electrochemical detector at 0.85 V (vs. Ag AgCl ). Factors that affect the immobilization and hydrolysis were investigated. The proposed method provides a simpler procedure with a less expensive material for glucosidase immobilization, and the electrochemical detection avoids the interference from other urinary species and hence simplifies the chromatogram obtained. The detection limit was 0.2 ng with a 20 μl injection. The relative standard deviations for 1.2 ng and 2.0 ng levels of phenols were 1.16% and 3.38%, respectively.

Separation behaviour of silica-containing mixed oxides as column packing materials for liquid chromatography

Four kinds of silica—containing mixed oxide gels (silica—zirconia, silica—alumina, silica—titania and silica—magnesia) were prepared by a coprecipitation method and studied as column packing materials for liquid chromatography. The physico-chemical characteristics of the gels such as the BET surface area and the acidity of the solid surface were determined. Further, the separation properties of these gels for benzene, dimethyl phthalate and pyridine were evaluated. It was found that silica—magnesia had the best separation ability for the basic compound pyridine, presumably owing to the decrease in the activity of the silanol group and the existence of only very weak acid sites on the surface.

Silica-Containing Mixed-Oxide Gels Prepared by a Coprecipitation Method as Novel Packing Materials for Liquid Chromatography

Abstract The separation characteristics of silica-zirconia. silica-alumina, Silica-titania, and silica-magnesia gels for benzene, dimethyl phthalate, and pyridine have been evaluated as column packing materials for liquid chromatography. Of these mixed-oxide gels, silica-magnesia had the best separation ability particularly for a basic compound, pyridine depending presumably on the reduction of the activity of silanol group on silica surface.

A new polymer supported packing material as a substitute of hydroxylapatite: Purification of Topoisomerases

Hydroxylapatite (HA), a form of calcium phosphate, finds extensive usages in the fractionation and purification of proteins, enzymes and nucleic acids. However, commercial HA preparations for liquid chromatography (LC) differ from many other LC packing materials in that the former is not polymer supported. We have now developed a substitute packing material which uses Fractosil 200 as the polymer support. Other polymer supports can also be similarly used. Being Fractosil 200 supported, this Hydroxylapatite Substitute (HAS) matrix can be employed for open column LC as well as for HPLC purposes. Although the exact chemical nature of HAS is different from the conventional HA, HAS mimicks the functions of the latter support. Due to the highi?½ binding capacity of HA many DNA binding proteins have been partially purified on this support. In the present work HAS has been successfully used in the partial purification of Topoisomerase I and II from wheat germ.

Direct coupling of packed fused-silica liquid chromatographic columns to a magnetic sector mass spectrometer and application to polar thermolabile compounds

Fused-silica columns of 0.22 mm I.D. packed with normal small-particle high-performance liquid chromatography packing material were studied. The shape of the column end allows direct connection to a combined electron impact—chemical ionization (EI—CI) ion source. To inject small volumes a syringe-loaded micro-sample injector is used with the time splitting technique. Mass spectra obtained from easily vaporized compounds are similar to, but display less thermal decomposition than, normal EI spectra. Mass spectra of underivatized native mono- and disaccharides give useful structural information. Results from the analysis of cardiac glucosides are also shown. The system provides high-efficiency chromatography with a universal detector, suitable for the analysis of non-volatile and labile compounds.

Analysis of Proteins with new, mildly hydrophobic high-performance liquid chromatography packing materials

A series of packings that had alkyl and aryl groups incorporated into a hydrophilic polymeric matrix were developed for hydrophobic interaction chromatography. Using an inverse salt gradient of ammonium sulfate or sodium chloride, a series of proteins were purified and the activity of trypsin was monitored using post-column detection. Retention times of proteins generally increased in the following order of ligands: hydroxypropyl, propyl, benzyl, isopropyl, phenyl and pentyl.

The evaluation of “reversed phase” high-performance liquid chromatography packing materials

For the evaluation of reversed phase packing materials a mixture of acetylacetone, I-nitronaphthalene and naphthalene is proposed. This will reveal the usual optimum kinetic chromatographic parameters (the naphthalene peak), the degree of activity or endcapping status of the column (the ratio of the I-nitronaphthalene and naphthalene retention times) and trace metal activity (the shape and intensity of the acetylacetone peak).

Some peculiar properties of cross-linked polyvinyl alcohol (CL-PVA) related to the reticulation degree

Unlike usual polyhydroxilic packing materials for liquid chromatography based on cross-linked agarose, CL-amylose and CL-dextrans (Sephadex), the cross-linked PVA gels exhibit an increase of swelling properties with the reticulation degree, up to a certain limit. Afterwards more advanced reticulation degrees induce a decrease in swelling capacities just as in case of other cross-linked polyhydroxilic polymers. This abnormal behaviour of CL-PVA was supposed as being due to the interchain hydrogen associations. IR spectra, X-ray data and 8 M urea treatments strongly supported our supposition pointing out a maximum association by hydrogen bonds in CL-PVA gels with a reduced degree of reticulation.

Isocratic multi-column high-performance liquid chromatography as a technique for qualitative analysis and its application to the characterisation of basic drugs using an aqueous methanol solvent

A variety of high-performance liquid chromatography packing materials were prepared and their chromatographic properties compared for separating several basic drugs using a single solvent system. The three most promising packing materials (silica, a mercapto propyl modified silica and a n-propyl sulphonic acid modification) were subsequently used to provide retention volume data for a large number of drugs.

Relationship between chromatographic performance and surface structure of alumina microspheres

Spherical alumina high-performance liquid chromatography packing material has been thermally modified at temperatures ranging from 200 to 950°. The chromatographic performance of the modified columns was tested using solutes of varying column capacity ratio ( k′ = 0–14), with n-hexane as the eluent. The parameters k′, α, and ϕ′ have been obtained and conclusions concerning the solute adsorption mechanisms at various temperatures have been postulated. The effects of pre-treatment of the alumina on the column characteristics prior to column packing are also discussed.