J.G. Heathcote

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose Part I. Qualitative separation

Abstract Using thin layers of cellulose powder and a new pair of solvent systems, forty amino acids and related compounds have been separated unambiguously on a single glass plate by two-dimensional chromatography. The positions of a further twenty-three compounds are also recorded.

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose : II. The quantitative determination of amino acids in protein hydrolysates

Abstract A simple and accurate method has been devised for the quantitative analysis of protein hydrolysates using thin-layer chromatography. Ninhydrin—cadmium acetate is the staining reagent and, using reflectane densitometry, calibration graphs have been drawn for twenty-two naturally occurring amino acids. The equation of the line for each amino acid has been calculated and used for the determination of the amount of amino acid present in protein hydrolysates. The results obtained agree well with those obtained by the ∝Technicon’ Automatic Amino Acid Analyzer and with those given in the literature.

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose : IX. The characterization of some histidyl, prolyl and lysyl dipeptides by thin-layer and ion-exchange chromatography

Abstract This paper is a continuation of previous work (Parts VI and VIII), designed to identify small peptides in biological fluids by a combination of ion-exchange and thin-layer chromatography. Three series of dipeptides, one having proline, another histidine and a third lysine as the N-terminal amino acid, have been examined.

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose : VI. The Characterization of small peptides by thin-layer and ion-exchange chromatography

Abstract In this paper, which is a continuation of previous work (Part VI), two series of dipeptides, one with leucine and the other with isoleucine as the N-terminal residue, have been examined by both ion-exchange and thin-layer chromatography. The possibility of identifying these compounds in biological fluids by a combination of these techniques has been demonstrated.

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose. 3. Detection and identification by selective staining.

Abstract A simple and rapid method is described for the detection and unambiguous identification of seventy-six nitrogen-containing metabolites which are commonly found in biological fluids. Following the separation of these compounds by thin-layer chromatography they are identified by means of selective staining reagents.

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose : Part IV. The quantitative determination of amino acids in urine

Abstract A new method is described for the accurate quantitative determination of amino acids in urine using thin-layer chromatography. Interfering salts and peptides are first removed from the urine by passing it through a column of an ion-retardation resin. The urine is then chromatographed on thin layers of cellulose and the amino acids are determined quantitatively by the method of H eathcote and H aworth . Several normal and pathological urines have been examined by this technique and quantitative recovery of standard amino acids has been obtained. The results obtained with individual urine samples agree well with those determined by the automatic ion-exchange method of analysis. The method seems to hold considerable promise for the analysis of amino acids in urine.

Improvements in the thin-layer chromatography of natural products. I. Thin-layer chromatography of the aflatoxins.

During the period which has elapsed since the aflatoxins were first isolated, one of the main problems has been the separation of the individual aflatoxins in pure form from aflatoxin-containing extracts. This separation has been best effected by thin-layer chromatography, and in this paper we describe how some of the difficulties may be overcome by using an appropriate combination of solvent system and silica gel preparation. For the examination of aflatoxin-containing extracts from the mycelia of Aspergillus flavus moulds, an initial freeze-drying step has been found to improve appreciably the quality of the chromatograms obtained.

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose: V. The quantitative detemrination of urea in urine

Abstract A simple, rapid method is described for the accurate quantitative determination of urea in undesalted urine using uni-dimensional thin-layer chromatography (H eathcote and H aworth ). The method is based on the formation of a stable coloured complex between urea and Ehrlichs reagent which is then estimated quantitatively. Several urine samples have been examined by this method and the results agree favourably with those obtained by two other standard procedures.

The influence of peptides on the analysis of amino acids by thin-layer and ion-exchange chromatography

Abstract The degree of sensitivity and of resolution of amino acids that is possible on cellulose powder makes thin-layer chromatography an ideal system for the analysis of protein hydrolysates. Its application to biological fluids is frequently unsatisfactory, even when salts have been removed, owing to the presence of peptides. The latter may also give rise to ambiguities between amino acids and peptides in the ion-exchange analysis of such fluids. This paper describes how some of these difficulties can be minimised by the use of both techniques concurrently.

An improved technique for the analysis of amino acids and related compounds on thin layers on cellulose : X. The characterization of some methionyl, phenylalanyl, tyrosyl and other peptides by thin-layer and ion-exchange chromatography

This paper is a continuation of previous work (Parts VI, VIII, and IX) designed to identify small peptides in biological fluids by a combination of ion-exchange and thin-layer chromatography. Several series of peptides, mainly dipeptides, with methionine, phenylalanine, tyrosine, aspartic acid, serine, or glutamic acid as the N-terminal amino acid, have been examined.