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At least 919 records · Page 51Linked to original sources
PubMed1988

High-performance liquid chromatography of amino acids, peptides and proteins. LXXXVI. The influence of different displacer salts on the retention and bandwidth properties of proteins separated by isocratic anion-exchange chromatography.

The influence of different displacer salts on the retention behaviour of seven globular proteins ranging in molecular weight from 12,000 to 69,000 was investigated using the Mono Q anion-exchange resin as the stationary phase. Isocratic retention data were collected using several different alkali metal halides as the displacing salt, thereby systematically varying the anion and cation species in the series F-, Cl- and Br- and Li+, Na+ and K+. The different anions were found to reduce protein retention in order of their decreasing hydrated ionic radii. Protein Zc values were found to be lower for fluoride and bromide than for chloride. It was demonstrated that the cationic co-ions also influence solute retention properties with this anion-exchange resin through, inter alia, preferential interactions with the protein solute. Protein band-broadening was found to systematically vary with the choice of displacer salt. These changes were related to known Hofmeister effects on protein aggregation kinetics and solubility and the degree of ion penetration at the double layer of the stationary phase-mobile phase interface. These studies now provide a rapid comparative basis for evaluating the mechanism of co- and counter-ion interactions with proteins in high-performance ion-exchange chromatographic systems.

Amino Acids↗
PubMed1988

Ion-exchange chromatography of proteins on a polyethyleneimine-grafted hydrophilic polymer for high-performance liquid chromatography.

A new, macroporous, synthetic polymer, Hydrophase HP-PEI, having highly hydrophilic surface characteristics enhanced by evenly distributed polyethyleneimine groups on its surface, was evaluated as an high-performance ion-exchange chromatographic packing material for the separation of proteins and nucleotides. A steel column (100 mm x 7.8 mm I.D.) packed with this material produces more than 33,000 plates per m. This base polymer included large proteins, such as thyroglobulin and apoferritin, in a size-exclusion mode. With various proteins it gave high recovery, high resolution and high capacity.

Chromatography, High Pressure Liquid↗
PubMed1990

High-performance liquid chromatography of proteins on deformed non-porous agarose beads. Fast boronate affinity chromatography of haemoglobin at neutral pH.

Aminophenylboronic acid was attached to epoxy-activated non-porous agarose beads with diameters of 12-15 microns and this boronate gel column was used for the fractionation of glycosylated from non-glycosylated haemoglobin. By varying the experimental conditions it was shown that the ratio between the second peak (glycosylated haemoglobin) and the first peak (non-glycosylated haemoglobin) was virtually independent of pH in the range 7-8, ionic strength, flow-rate and sample load (up to at least 160 microliters of haemolysate on a 0.7-ml column). It is therefore not necessary to control thoroughly these parameters in order to obtain reproducible results, which is a great advantage in fast routine analyses of glycosylated haemoglobin. At a flow-rate of 4.0 ml/min an analysis was finished within 2 min on a 2.5 cm x 0.6 cm I.D. column. The total time of an analysis was also short because a sample from a droplet of blood could be applied directly onto the column after haemolysis for 1 min without removal of cell debris by time-consuming centrifugation. The experiments were performed at a pH close to the isoelectric point of haemoglobin, because at this pH haemoglobin has a negligible net charge and will therefore not interact with the charged groups of the ligands, the matrix and proteins adsorbed in previous runs.

Boron Compounds↗
PubMed1984

Trace analysis of the antihistamines methapyrilene hydrochloride, pyrilamine maleate and triprolidine hydrochloride monohydrate in animal feed, human urine and wastewater by high-performance liquid chromatography and gas chromatography with nitrogen-phosphorus detection.

Toxicological evaluation of the antihistamines methapyrilene hydrochloride, pyrilamine maleate, and triprolidine hydrochloride monohydrate using methapyrilene hydrochloride as the positive indicator was investigated as part of a structure-activity relationship study in rats and mice. Prerequisites for the toxicological tests were the development of analytical procedures to certify the dose, homogeneity and stability of the drugs in animal feed and to monitor human urine for possible exposure and to ensure removal of the test agents from wastewater prior to its discharge into the environment. A high-performance liquid chromatographic (HPLC) system was developed using a fluorescence detector for the determination of methapyrilene hydrochloride and pyrilamine maleate in feed at levels as low as 100 ng/g and in human urine as low as 1 ng/g. An HPLC-UV procedure was developed for the determination of triprolidine hydrochloride monohydrate in feed at levels as low as 10 micrograms/g. Data concerning p-values, extraction efficiencies from feed and stability experiments in feed are presented for these antihistamines. A gas chromatographic procedure using a nitrogen-phosphorus detector was also developed for determining the three antihistamines in admixture in wastewater at levels as low as 10 ng/g.

Animal Feed↗
PubMed2001

Analysis of free and esterified sterols in fats and oils by flash chromatography, gas chromatography and electrospray tandem mass spectrometry.

A method for the analysis of free and esterified sterols has been developed. Fat or oil samples were separated on solid-phase extraction silica gel columns into a sterol ester fraction, a fraction of triacylglycerols, and a free sterol fraction containing partial acylglycerols and residual triacylglycerols. Sterol esters and acylglycerols of the free sterol fraction were transesterified to methyl esters. The fatty acid methyl esters from sterol ester fraction and the free sterols from sterol ester fraction and free sterol fraction were determined by GLC. Precursor ion electrospray MS-MS of sterol fragment ions of sterol ester fractions were recorded and used for determination of sterol ester proportions in butterfat and vegetable oil samples.

Chromatography↗