Die Formoltitration der Aminosäuren im Harne. Vorläufige Mitteilung.

Malfatti, H.

doi:10.1515/bchm2.1909.61.6.499

Cited by 9 publications

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“…Where this is done, no claim as to quantitative accuracy based on the titration of single amino acids as above can be made, as it has no reference to working conditions. This inherent defect should not be forgotten if applying analytically such methods as the formaldehyde methods of Malfatti (1909) and Cole (1928), or the alcohol methods of Foreman (1920) and Grassmann and Heyde (1929). Nevertheless these titres will bear an approxi mately constant ratio to true amino-N, whereas two-indicator methods will vary fortuitously according to the presence of phosphates, etc.…”

Section: Comparative Titrationsmentioning

confidence: 99%

“…For the estimation of amino nitrogen in complex fluid mixtures three typical methods are available. These are (a) the nitrous acid method ( Van Slyke, 1911, 1912, ( 6) the formaldehyde titration (Sorensen, 1907 ;Malfatti, 1909 ;Liiers, 1920), and (c) the alcohol titration (Foreman, 1920;Willstatter and Waldschmidt-Leitz, 1921). Yet by general agreement none is entirely satisfactory.…”

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confidence: 99%

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Critique on the biological estimation of amino nitrogen

1934

Proc. R. Soc. Lond. B.

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For the estimation of amino nitrogen in complex fluid mixtures three typical methods are available. These are ( a ) the nitrous acid method (Van Slyke, 1911, 1912), ( b ) the formaldehyde titration (Sørensen, 1907; Malfatti, 1909; Lüers, (1920), and ( c ) the alcohol titration (Foreman, 1920; Willstätter and Waldschmidt-Leitz, 1921). Yet by general agreement none is entirely satisfactory. Method ( a ) is tedious in multiple determinations, is subject to fortuitous error from frothing, and from reducing agents present in solution. It is known to give faulty values for glycine, cystine, tryptophane, arginine, lysine, and glutamine (Schmidt, 1929; Plimmer, 1924; Chibnall and Westall, 1932), and for various peptides (see Thierfelder and von Cramm, 1919; Hopkins, 1929; Dunn, Butler, and Deakers, 1932). As discussed later, it gives a partial estimation of ammonia, urea and allantoin, creatinine, and the aminopurines. It is not influenced by proline (Van Slyke, 1911). Methods ( b ) and ( c ) have much in common. They are both rapid in use, but are of limited accuracy owing to a difficult end-point in complex solution, and of restricted scope since they must be confined to almost colourless extracts. Their quantitative defects are to be discussed, but the methods are best applied serially only to solutions of closely similar chemical composition. As a final option, colurimetry (Harding and MacLean, 1916; Riffart, 1922; Folln and Wu, 1922) is both too uncertain and too difficult to apply to chemically complex, coloured solutions.

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Section: Comparative Titrationsmentioning

confidence: 99%

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confidence: 99%