During recent work on the mechanism of the ATP-CoA-acetate1 reaction (1, 2) we observed that, on incubation of yeast enzyme with ATP, CoA, acetate, and hydroxylamine, a substance was formed in the presence of fluoride which, although initially colorless with the Fiske-Subbarow phosphate reagents (3), slowly developed on standing a blue color of a somewhat more purplish shade than that obtained ...

A simple spectrophotometric method is reported her for the estimation of reserpine in polyherbal formulations. Estimation is based on the reaction with3-methylbenzolinone-2hydrazone (MBTH) reagent in presence of cerric ammonium sulphate to yield a violet coloured chromogen, which exhibits and absorption maxima at 580 nm. The chromogen is stable for 10 minutes.

The conventional starch determination (employing precipitation, filtration, re-dissolution, colour development) is compared with a simplified direct colorimetric procedure, which is readily automated. The reproducibility is better than 3%, with a correlation coefficient of 0,87 between the two methods.

The difficulty of applying classical procedures to the qualitative and quantitative determination of carbohydrate in certain biological materials has led to the development of calorimetric methods in which the carbohydrate-containing material is treated with strong mineral acids, causing t,he formation of substances which will react with compounds such as diphenylamine, resorcinol, orcinol, ind...

With the use of titrimetric (1)) manometric (2)) stalagmometric (3), and calorimetric (4, 5) techniques, the esterase and lipase activities of sera and many tissues have been measured by employing a wide variety of substrates (6). The vast amount of data that resulted from these studies contains numerous discrepancies in the behavior of these esterolytic enzymes, which are still unexplained. Tw...

We show how zinc may easily be quantified in serum by first using an optimum concentration of guanidine hydrochloride to cause release of zinc from proteins, followed by complexation of released metals with cyanide. The cyanide complex of zinc is preferentially demasked with chloral hydrate, followed by a colorimetric reaction between zinc and 4-(2-pyridylazo)resorcinol. This is a sensitive wat...

Kober (1931) was the first to suggest a calorimetric test for urinary estrin. He compared the degree of red color developed after treatment with phenolsulfonic acid in a test sample with a standard cresol red solution. Cohen and Marrian (1934) modified the Kober procedure and determined the hormone content of estrone and estriol fractions by comparison with a standard curve from a set of determ...

Most of the methods described for the determination of acetoin and biacetyl are based on the original Lemoigne-van Niel procedure (1, 2), which depends upon the formation of insoluble nickel dimethylglyoxime when biacetyl is treated with hydroxylamine in the presence of a nickel salt; acetoin is similarly determined after oxidation to biacetyl by heating with ferric chloride. In a recent modifi...

A novel compound, N,N'-bis(2,4-di-sulfobenzyl)tolidine tetrasodium salt (SBT), was synthesized for use as a chromogenic indicator for oxidizing substances, and its applicability to the colorimetric determination of chlorine in water was examined.