Liquid Chromatographic System For Separation Research Articles

Microcomputer-assisted liquid chromatographic separation system: application to toxic compounds identification in poisoned human fluids.

The computer-assisted liquid chromatographic system (MCASYST) is developed for automated identification and analysis. The system has six main functions: retention prediction system, liquid chromatographic data base system, automated identification system, optimization of separation conditions, data loading program from UV multichannel detector, and UV spectral data base system. The performance and potential of this MCASYST system is evaluated for toxic compounds identification in poisoned human fluids.

Analytical high-performance liquid chromatography system for separation of components in nonoxynol-9 spermicidal agents

Analytical high-performance liquid chromatography system for separation of components in nonoxynol-9 spermicidal agents

Analytical high-performance liquid chromatography system for separation of components in nonoxynol-9 spermicidal agents

Analytical high-performance liquid chromatography system for separation of components in nonoxynol-9 spermicidal agents

Determination of protein size in chromatography column eluants by on-line photon correlation spectroscopy

The dynamic light scattering technique of photon correlation spectroscopy has been used to determine biomacromolecule hydrodynamic radius in solutions flowing at rates similar to those experienced in liquid chromatographic separation systems. Such analyses can be performed rapidly (<5 s). The potential of the technique as an on-line noninvasive monitor for liquid chromatography is discussed.

Nonaqueous Reverse Phase Liquid Chromatographic System for Separation and Quantitation of Provitamins A

A reverse phase liquid chromatographic (LC) system has been developed for separating the main naturally occurring carotenoids that have provitamin A activity. The system produces baseline separation of beta-carotene, alpha-carotene, and beta-cryptoxanthin (beta, beta-carotene-3-ol, 472-70-8) from biologically inactive zeinoxanthin (beta, epsilon-carotene-3-ol, 24480-38-4) and from a pigment believed to be alpha-cryptoxanthin (beta, epsilon-carotene-3'-ol). Some cis-isomers are also separated. These separations are obtained on a C-18 column, isocratically, with methanol-chloroform eluant. For quantitation, peak areas from detection at 475 nm are compared with that of an internal standard, 1-(phenylazo)-2-naphthalenol (842-07-9), which elutes prior to the provitamins. Provitamin amounts are calculated from absorbance ratios. Prior to LC, esters are saponified, and interfering pigments are removed from ester-free extracts by adsorption on magnesia.

Automated tandem high-performance liquid chromatographic system for separation of extremely complex peptide mixtures

We have developed an automated tandem chromatography system, which consists of a combination of ion-exchange column chromatography and reversed-phase column chromatography. The system is composed of two independent high-performance liquid chromatography assemblies, in each of which programmed elution is carried out by a computer-assisted controller. A peptide mixture is applied to an ion-exchange column and is eluted in a stepwise manner. The eluent from the first column is introduced directly into the second, reversed-phase column, which is connected in tandem through a tee tube. After application of two column volumes of the eluent, reversed-phase chromatography is performed by linear gradient elution. Stepwise elution for ion-exchange chromatography and the gradient elution for reversed-phase chromatography are synchronized by a computer program. The resolving power and the reproducibility of the method were tested by using a tryptic digest of human ceruloplasmin [molecular weight 132 000 daltons (132 kDa)]. By this method, the digest was resolved reproducibly into several hundred peaks within 16 h. All of the four glycopeptides expected to be obtained by tryptic digestion were purified easily from the whole digest of the protein. Comparison of the peptide maps between a single-chain and a degraded form of ceruloplasmin facilitated the identification of two tryptic peptides, derived from the carboxyl-terminal regions of 67 kDa and 50 kDa fragments of the degraded form, which lack the carboxyl-terminal arginine and lysine residues, respectively. The method may be applicable to comparative peptide mapping of very large proteins exhibiting molecular microheterogeneity, such as carbohydrate or genetic variants; it also can be used complementarily for sequence support of DNA sequencing as well as for preparative purification of peptides as a strategy of protein sequencing of very large proteins.

High-performance liquid chromatographic assay of 6-methylthioguanine, a major metabolite of 6-thioguanine, in urine

A flow-fluorimetric high-performance liquid chromatographic assay for 6-methylthioguanine in urine has been developed. This compound is a major catabolite of 6-thioguanine, an important drug in cancer chemotherapy. The metabolite was extracted from alkaline urine with ethyl acetate which was injected onto a reversed-phase high-performance liquid chromatographic system for separation and detection. The method is simple, rapid and sensitive to below 500 ng ml −1 which is below the levels encountered following a therapeutic dose of 6-thioguanine. Another metabolite was chromatographically separated from 6-methylthioguanine and partially characterised.

Pyrimidine nucleoside phosphorylase assay by automated high-performance liquid chromatography

A new assay for pyrimidine nucleoside phosphorylase is reported. This method utilizes an isocratic reversed-phase high-performance liquid chromatographic system for separation of nucleosides and bases. Product detection is accomplished by ultraviolet monitoring and radioactive flow detection. Use of an automated sample injector allows for the analysis of a series of samples, with data recorded onto a microprocessor-based cassette recorder. Data can then be downloaded into computer memory. The velocity of uridine phosphorylase (E.C. 2.4.2.3) was a linear function of enzyme concentration. The Michaelis constant for uridine at pH 8.0 was found to be in close agreement with the value obtained by a thin-layer chromatographic assay method.

Optimization of precolumn design in liquid chromatography

The influence of precolumn design on the efficiency of liquid chromatographic separation systems which involve the use of an on-line trace-enrichment step has been studied. For most practical purposes, precolumns having an inner diameter of 2–4.6 mm and a length of l0–2 mm can be recommended; these allow sampling flow-rates of up to at least 10 ml min -1 at a back pressure of 1–10 MPa. Within this range, the precolumn geometry does not appear to be critical in the on-line trace enrichment of either strongly retained or more weakly retained analytes. A new precolumn design is presented which allows rapid slurry packing with a micro-spatula or via syringe loading, and easy replacement of low-cost precolumn cartridges.

Determination of Carbonyl Compounds in Automobile Exhausts and Atmospheric Samples

Abstract Two new methods were developed to determine carbonyl compounds in auto exhaust and atmospheric samples. A gas Chromatographic system using a quartz glass capillary column combined with selective and sensitive electron capture detection was used. 2,4-Dinitrophenylhydrazone derivatives of the carbonyl compounds are electron capture sensitive. The aldehydes and ketones were trapped in impinger sampling flasks containing the reagent solution. The excess of reagent was removed before injection onto the glass capillary column. A reversed phase high performance liquid chromatographic system for separation of fluorigenic dansylhydrazones is presented. With this system a complete separation of 17 carbonyl compounds was achieved. The reaction conditions for the dansylhydrazine reagent was studied and compared to the 2,4-dinitrophenylhydrazine reagent. The gas chromatographic method was also compared to the different liquid chromatographic methods applied on some atmospheric and auto exhaust samples. The me...