Colorimetric Determination of Amino-acid Concentration

Colorimetric determination of hippuric acid in urine and liver homogenate.

To a dried extract Containing hippuric acid (HA), 1.0 mL of acetic anhydride and 2.0 mL of 0.5% p-dlmethyiamlnobenzaldehyde (DAB) solution In pyridine were added, and the solution was kept at 40 O C for 1 h after thorough mlxing. The absorbance was then determlned at 458 nm agalnst a blank containing acetic anhydride, DAB, and pyridine. This method was in good agreement with Beer’s law within 1...

Direct colorimetric determination of hippuric acid in urine.

In 1963 Umberger and Fiorese (1) introduced a colorimetric method for HA,1 based on the color reaction of HA, dissolved in anhydrous pyridine, with BSC. Therefore, for applying their method to determine HA in urine, HA must first be extracted from the urine. We found that HA dissolved in water-pyridine (1:1, by vol) produces a red-orange color when BSC is added at room temperature. The absorpti...

The Colorimetric Determination of Lactic Acid in Biological Material

The colorimetric determination of lactic acid in silage.

The fundamental reaction which takes place in the process of ensilage is the conversion of a proportion of the soluble carbohydrates present to lactic acid. This reaction is of such importance that when material of high protein content is being ensiled, it is desirable to add molasses to provide a readily available substrate for the lactobacilli which occur along with coliform organisms in the ...

Colorimetric Determination of Serum

In the past few years there has been renewed interest in the study of serum cholinesterase in various disease states, particularly those affecting the liver. Recently, a colorimetric method for the determination of this enzyme in the serum was reported by Ravin, Tsou, and Seligman (1). Their method, simple to perform, is as accurate as the gastrometric technique and more specific than the elect...