Abstract: The invention provides a novel crystalline potassium salt of .beta.-nicotinamide adenine dinucleotide phosphoric acid (.beta.-NADP-K), having a primitively orthorhombic crystal system, which salt is more pure and more stable than the conventional amorphous form, and is advantageously not hygroscopic. The novel salt is produced by treating a dilute aqueous solution of the potassium salt of .beta.-nicotinamide adenine dinucleotide phosphoric acid with a hydrophilic water soluble organic solvent at a pH value of 2 to 5 until turbidity sets in, permitting crystallization and then separating the crystals.

Abstract: Crystalline orthorhombic potassium adenosine-5'-diphosphate having the space group P2.sub.1 2.sub.1 2 and the elemental cell constantsa=28.53.+-.0.03 Ab=10.49.+-.0.02 Ac=6.33.+-.0.02 A.alpha.=.beta.=.gamma.=90.0.degree.volume=1894.4 A.sup.3,has superior stability, relative to conventional salt forms thereof, e.g., the disodium salt.

Abstract: In a conventional method for the quantitative determination of substances, particularly in serum, which, by action of an oxidase thereon, combine with oxygen to form hydrogen peroxide and wherein the hydrogen peroxide formed is converted, in the presence of methanol and catalase, to formaldehyde, the formaldehyde is reacted with hydrazone in the presence of ferric chloride, and the dye thus formed is determined photometrically, the improvement comprising using as the hydrazone, 3-methyl-2-sulfonylbenzothiazolone-hydrazone; use of this hydrazone results in the formation of a very easily soluble dye and is suited for use in automatic analyzers.

Abstract: .gamma.-Glutamyl-4-nitroanilide compounds of the formula ##STR1## wherein R is a .gamma.-glutamyl radical and X is an acid group, and salts of such compounds, are used to determine .gamma.-glutamyl-transpeptidase by contacting a sample suspected of containing .gamma.-glutamyltranspeptidase with said compound and glycylglycine and determining the liberation of the resulting p-nitro-aniline compound as a measure of the .gamma.-glutamyltranspeptidase activity initially present in the sample.

Abstract: .gamma.-Glutamyl-4-nitroanilide compounds of the formula ##SPC1##Wherein R is a .gamma.-glutamyl radical and X is an acid group, and salts of such compounds, are used to determine .gamma.-glutamyltranspeptidase by contacting a sample suspected of containing .gamma.-glutamyltranspeptidase with said compound and glycyl-glycine and determining the liberation of the resulting p-nitroaniline compound as a measure of the .gamma.-glutamyltranspeptidase activity initially present in the sample.

Abstract: .gamma.-Glutamyl-4-nitroanilide compounds of the formula ##SPC1##Wherein R is a .gamma.-glutamyl radical and X is an acid group, and salts of such compounds, are used to determine .gamma.-glutamyltranspeptidase by contacting a sample suspected of containing .gamma.-glutamyltranspeptidase with said compound and glycylglycine and determining the liberation of the resulting p-nitroaniline compound as a measure of the .gamma.-glutamyltranspeptidase activity initially present in the sample.