Quantitative data are presented on ninhydrin-reacting substances in hydrolysates and extracts of Recent sediments, sedimentary rocks, and fossils, as determined by column chromatography. The recovery of amino acids added in small amounts to a concentrated calcium chloride solution was found to be 94-96 per cent, after precipitation of the calcium as calcium sulphate and removal of the HCl by vacuum distillation. Seventeen amino acids and three unknowns were detected in hydrolysates of surface and subsurface sediment samples, from Lake Opinicon, Ontario, with amino acids and other ninhydrin-reacting organic compounds accounting for nearly two-thirds of the soluble-N in the hydrolysate, and ammonia for most of the remaining third. Only five amino acids, (aspartic acid, glutamic acid alanine, leucine(s) and γ-aminobutyric acid) and one unidentified ninhydrin-reacting organic compound were present in a hydrolysate of shale from the Green River formation, (Eocene). Amino acids accounted for only 0.014 per cent of the total-N in the shale. It was calculated from the alanine content that the maximum temperature that the Green River shale could have been continuously subjected to during its history was 74°C. Amino acids were not detected in hydrolysates of two pre-Cambrian sedimentary rocks, nor in it hydrolysate of a Miocene lignite. An acid extract of carnosaur "teeth" from the Upper Cretaceous contained leucine(s), ammonia, ethanolamine, and one unidentified ninhydrin-reacting substance that chromatographed similarly to an unknown found in a hydrolysate of laboratory heated Mercenaria shells. Of the total-N in a shell of the univalve mollusc Casis Madagascarensis, 50 per cent was extractable with cold HCl, this fraction consisting of amino acids, ammonia and unidentified compounds, some of which reacted with ninhydrin. Only 57 per cent of the nitrogen in a hydrolysate of the conchiolinfraction of the shell was recovered in the form of amino acids and ammonia. Fifteen amino acids and two unknowns were detected in the hydrolysate of the conchiolin-fraction. The periostracum of a Pleistocene Mercenaria mercenaria shell liberated sixteen amino acids and three unidentified ninhydrin-reacting substances on acid hydrolysis. The periostracum-free fossil shell had approximately the same amino acid composition as reported elsewhere for shells of living Mercenaria. Quantitative data on amino acids and other ninhydrin-roacting compounds were reported for samples of Pleistocene Mercenaria shells pyrolysed in the laboratory at 213 and 219x000B0;C. In the shell, alanine decomposed at a faster rate, and plienylalanine at an equal or slower rate, than the rates characteristic of the same amino acids in dilute aqueous solution. The nitrogen liberated from amino acids during pyrolysis could mostly be accounted for in the hydrolysates as acid-insoluble-N, ammonia, and soluble nitrogenous compounds, some of which reacted with ninhydrin. Amines were detected only in samples pyrolysed in sealed tubes.
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Jul 30, 2024
Bo Meng + 2
Open Access